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Saturday, February 28, 2009

Start out smart – Plant Disease Resistant Vegetable Varieties

Michelle Grabowski, University of Minnesota Extension Educator

Photo 1: Fusarium wilt resistant and susceptible tomato seedlings. Michelle Grabowski

Although winter still holds Minnesota in its icy grasp, smart gardeners are already pouring over seed catalogs and preparing for the season ahead. There are many factors to consider when choosing which vegetable variety to grow this season. One option available to gardeners is disease resistant varieties. These are varieties that have been specially bred or selected for their ability to remain healthy in the presence of a pathogen. Choosing disease resistant vegetable varieties can save the gardener time and money since they will likely not require fungicide sprays or other control measures to prevent the development of fruit rot, leaf spots or other disease problems.

In order to make educated decisions about purchasing disease resistant seed, there are a few terms that gardeners should be familiar with. According to the American Phytopathological Society, a resistant plant is a plant that possesses properties that prevent or impede disease development. A fully resistant vegetable variety will not become diseased even if the pathogen is present and the environmental conditions favor disease development. Many vegetable varieties are moderately resistant or partially resistant, meaning that they cannot block all disease development but often are able to resist the pathogen enough to remain far healthier than a plant without any resistance. Similarly a tolerant plant is able to endure disease without serious damage or yield loss. For example a powdery mildew tolerant squash variety may have some powdery mildew on its leaves, but is likely to produce a good crop none the less.

Look for resistant varieties on seed packets or plant labels and in plant catalogues. Many companies indicate disease resistance with a series of initials after the variety name or within the description of the plant. For example a pumpkin labeled PMT means that this variety is powdery mildew tolerant. All initials are typically defined somewhere in the catalogue but you may have to flip a few pages to find the list.

Look for varieties that list resistance to a specific disease problem. For example tomatoes are often listed as VF, resistant to Verticillium wilt and Fusarium wilt. This tells you that the variety has been tested with a specific pathogen and found to be resistant to it. The genetic make up that results in a resistant plant is typically specific to one disease only, although it is possible to combine multiple genes for disease resistance into one variety. Broad unspecific claims, like Good Disease Resistance are typically not very useful. This may indicate a plant that is generally vigorous, but it is unlikely that the plant has been tested against any specific disease problem.

Remember not all plant diseases are common in Minnesota. Look for varieties with resistance to diseases that have been a problem in your garden in the past or are common in Minnesota. For some plant diseases there are many varieties to choose from that all have disease resistance. This allows the gardener to choose disease resistant seed and also select for several other characteristics. For example there are now many pumpkin varieties with tolerance, moderate resistance or complete resistance to powdery mildew. These disease resistant pumpkins vary from small to large and ribbed or smooth in their fruit characteristics and may grow as a large vine or a small bush. Unfortunately there are not disease resistant varieties for every plant disease. Some diseases like Septoria leaf spot of tomato plants and common smut on sweet corn occur in Minnesota every year, but no resistant variety has been discovered yet. A very comprehensive list of disease resistant vegetable varieties is available from Cornell University at

Common Diseases in MN
Resistant or Tolerant Varieties
Asparagus Rust and Fusarium Crown RotJersey Knight, Jersey Giant, other ‘Jersey’ varieties
Green BeansSeveral fungal and bacterial leaf spots, several virusesMany varieties available
CucumberPowdery mildew, Scab, several viruses Many varieties available
PeasPowdery Mildew, root rot PM resistance available in many varieties, ‘Strike’ is resistant to Pythium root rot
Sweet Corn Rust and SmutTolerance and moderate resistance to rust available in several varieties. No smut resistance available
TomatoesEarly Blight

Verticillium wilt
Mt. Fresh and JTO-99197 offer some resistance to early blight.

Many varieties resistant to verticillium
PeppersBacterial Leaf Spot Several varieties available
Pumpkins and SquashPowdery Mildew several viruses Many varieties available

Three New All-America Rose Selection (AARS) Winners Announced for 2009

David C. Zlesak, University of Minnesota Extension Educator


Photo 1: Carefree Spirit™ shrub rose. David Zlesak

Carefree Spirit™ (shrub rose), Pink Promise™ (hybrid tea rose), and Cinco de Mayo™ (floribunda rose) are the three new All-America Rose Selections (AARS) winners for 2009. These roses have proven themselves as top performers among dozens of entries over two seasons of evaluation at over 20 official test gardens across the country.

Carefree Spirit™ is a cheerful, single-flowered shrub rose with a profusion of red blooms with white eyes throughout the growing season. It is relatively compact in Minnesota, producing a mounded, slightly spreading plant that reaches a couple feet in height and a few feet in width. Carefree Spirit™ is a descendant of the famous Carefree DelightTM and shares its strong disease resistance. Carefree Delight™ is an AARS winner from 1996 and is still very popular in northern landscapes. Both roes were bred in France at Meilland International and introduced by the Conard-Pyle Company of West Grove, Pennsylvania.  Beginning in 2004, the AARS trials have stopped spraying preventatively with fungicides on the landscape trial roses (of which shrub roses are included).  Carefree Spirit™ was in the trials in 2005 and 2006 (2007 and 2008 were needed for propagation) and is the first winning landscape rose since this change, attesting to its disease resistance.      


Photo 2: Pink Promise™ hybrid tea rose. David Zlesak

Pink Promise™ is a classic hybrid tea, producing large flowers on long, cutting-length stems.  Double, well formed blooms are a beautiful blend of pink and white.  The flowers are richly fragrant and plants have above average disease resistance for a hybrid tea. This rose has done particularly well at trial sites in cooler regions of the country. Pink Promise™ was bred by Jim Coiner and introduced by Coiner Nursery of Lavern, California. A portion of the sales will go to support breast cancer education and early detection efforts.


Photo 3: Cinco de Mayo™ floribunda rose. David Zlesak

Cinco de Mayo™ is a colorful floribunda that produces flowers with a unique combination of orange with purple overtones.  It is a prolific flowering, vigorous plant like one of its parents, AARS winner Julia Child™.  The deep purple new growth adds extra interest and excitement to the celebration. Cinco de Mayo™ was bred by Tom Carruth of Weeks Roses located in Rancho Cucamonga, California.  He also bred a similar colored rose, Hot Cocoa™, which was a 2003 AARS winner.

AARS has a strong Minnesota connection

There are two official AARS test gardens in Minnesota: the Lyndale Park Rose Garden located in Minneapolis near Lake Harriet (AARS site since 1946) and the Virginia Clemens Rose Garden in St. Cloud, MN which was added relatively recently (2005). These gardens have the unique distinction of being the two most northern AARS test sites. Both of these test sites are open to the public, allowing gardeners to have a sneak preview and try their hand at predicting future AARS winners. These gardens also provide the opportunity to observe present and upcoming trends in rose breeding and marketing. For instance, in recent years there has been an increase in the proportion of shrub or landscape roses. This reflects the greater interest among rose nurseries and the general public for lower maintenance roses for landscape use. If there is a rose you find that you particularly enjoy and it does not win an award, that does not mean you will not have the opportunity to buy it in the future. Many of the roses that do not win AARS awards will also be introduced if they perform well at least regionally or have some traits which make them especially unique.


Photo 4: Lyndale Park Rose Garden in Minneapolis. David Zlesak

In addition to the two official Minnesota trial sites, there are two additional AARS gardens in Minnesota that serve as display gardens. These public gardens receive plants of AARS winners the season before they are official winners. This gives the gardening public and press an opportunity to observe the new winners early at four Minnesota locations. The two Minnesota AARS display gardens are the Leif Erikson Rose Garden in Duluth and the Nelson Shrub Rose Garden at the Minnesota Landscape Arboretum in Chaska. The 2010 winners will be featured in these four Minnesota gardens and well labeled beginning in June 2009 so as not to add confusion and detract from the spring sales of the 2009 winners.

Seed Savers Garden: A Demonstration of Genetic Variability

David C. Zlesak, Elizabeth Spedaliere, Kathy Bonnett; University of Minnesota Extension Educator and Master Gardeners, respectively

We often hear the saying that saving and starting seeds from hybrids typically leads to inferior plants or plants with too much variability to be worth our while. Even if some variability exists between the seedlings, is it actually so great or the plants so overall inferior that it wouldn’t be worth our effort? To what extent can this be true?

We decided to put this general recommendation to the test and develop a demonstration garden (Seed Savers Garden) at the Master Gardener Education and Research Display Garden at UMore Park in Rosemount, Minnesota to observe what happens.  In the fall of 2007 open pollinated seed was saved off a number of flower and vegetable seed-propagated varieties growing at the University of Minnesota Display and Trial Gardens in St. Paul and the authors’ gardens.  In the spring of 2008 seedlings were started in March in the greenhouse from the saved seed and also purchased seed of the same varieties for comparison.  Some of these seed-propagated varieties were reported to be F1 hybrids and others did not have their breeding methodology disclosed.  In addition to flower and vegetable seed-sold varieties, seed was also saved from some clonally-propagated flower cultivars (‘Lilliput Rose’ penstemon, Mammoth™ ‘Yellow Quill’ mum, and ‘Petite Delight’ monarda) and the seedlings planted out and compared to cutting-propagated plants purchased of the original cultivar.


The plants were planted in rows at UMore Park in June 2008. This fantastic garden is along highway 46 and free and open to the public between sunrise and sunset. Information and directions to this garden can be found at:  We planted the row of the original variety next to the row of the seedlings of that variety for easy comparison. Some varieties had limited numbers of plants and both the original variety and plants from saved seed were planted in a single row (in the following photos the original variety is to the left if there are two rows or to the front of the row if there is only one row and the bars represent mean values with standard deviations). Up to 14 plants each of the original variety and plants from saved seed were planted out. During the growing season when the particular species came either into flower or fruit, data was collected on plant size, flower/fruit number, and other traits that came to mind as being appropriate to document.  For some species data was taken again later in the season because as the plants continued to mature, greater differences were evident or, as in the case of tomatoes, ongoing, weekly fruit yield was recorded and ultimately summed over weeks.

Sometimes, seed packets did not tell us if the variety is an F1 hybrid or an open pollinated variety.  F1 hybrids are developed by crossing two distinct inbred lines that differ from each other and produce a superior hybrid.  They tend to be very vigorous, uniform, and are heterozygous for many traits because the original parents had different alleles for particular genes.  In the next generation, these alleles (forms of a gene) segregate and there can be a lot of variation among the seedlings depending on how these alleles reshuffle in each offspring.  Open pollinated varieties are cheaper to produce as different parental lines are not independently selected and maintained and then crossed to produce seed as in F1 hybrids.  For open pollinated varieties, plantings are made and parents possessing the traits desired are allowed to survive and intermate (those that don’t have the intended traits are pulled out) and seed is saved.  After multiple generations of doing this, the seedlings can come relatively true to type as the genes contributing to undesirable “off-types” have been generally been removed from the population. Following are the summarized results for each variety comparison followed by a general conclusion and some considerations.


Dianthus ‘Dulce White’


Plants from purchased seed performed much better than those of saved seed.  They had greater vigor with fuller, more floriferous plants.  All the plants from the saved seed were uniform for white flowers. Although the seed packet didn’t say, having such a decline in vigor among plants from the saved seed suggests ‘Dulce White’ is an F1 variety.

Dianthus ‘Elation Red’


Plants from purchased seed, again, performed much better than that of saved seed.  They had greater vigor, more floriferous plants, and were uniform for dark red flower color.  Plants from the saved seed segregated for multiple traits including the ability to flower and also flower color.  Only one plant from saved seed had dark red flowers like the parent.  The others had salmon or pink flowers.  Sweet williams are also in the genus Dianthus and do not flower until their second year after they have experienced a cold treatment from experiencing winter.  Having this trait appear among the seedlings was very interesting.  There were no sweet williams or other Dianthus species nearby that possessed this trait from which to pollinate the parents. The inheritance of many traits in the seed crops we purchased have not been disclosed and are kept proprietary by seed companies.  The possibility exists that this variety is an F1 hybrid and is the result of crossing a dianthus that requires a cold treatment with one that doesn’t and the requirement for cold is recessive.  It is not expressed in the F1 hybrid, which is a carrier.  The trait then segregates in the next generation.

Marigold ‘Starfire’


This marigold has petite foliage, is well-branched, and has an abundance of single flowers in a wide assortment of colors.  Plants from the saved and original seed are very comparable.  This variety is likely not an F1 hybrid and is an open pollinated variety.  It appears that breeders selected plants with a generally uniform, compact, mounded plant habit and preferred to keep variation for color within their populations.  The result is mixed colors and relatively uniform plant size both purchased and saved seed.

Monarda ‘Petite Delight’


Monarda ‘Petite Delight’ is a clonally propagated cultivar.  It is patented and the cultivar is propagated from cuttings or crown divisions (it is a perennial).  The unique trait for this cultivar is that it is very dwarf in stature compared to other monardas on the market.  Purchased plants of this patented cultivar were planted that were propagated from cuttings and compared to the seedlings.  Unfortunately, the purchased plants were very weak and stunted, had curled leaves, and did not flower (photo is of the original plant at the St. Paul Display and Trial Garden from which seeds were saved).  Perhaps they were infected with virus. The seedlings grew well and also did not flower.  Seedlings were quite variable for plant size and had normal looking foliage.

Chrysanthemum Mammoth™  ‘Yellow Quill’


Chrysanthemum Mammoth™ ‘Yellow Quill’ is also a clonally propagated, patented cultivar.  Seedlings were variable and segregated for flower color and also flowering time.  Some were clearly earlier and later in flowering (row of three flowers on top are of the original cultivar and the five flowers beneath are of the seedlings that were in flower September 3, 2008).  Although quite a bit of variability was found among seedling, since mums are a perennial, the potential is there to select and multiply very attractive, hardy seedlings through dividing them and taking stem cuttings.  One can use saved seed to develop unique individuals from which to become new clonally propagated cultivars.

Pansy ‘Antique Rose’


This pansy has well-branched, vigorous plants with above average heat tolerance and an assortment of colors.  Plants from the saved and original seed are very comparable.  This variety is likely not an F1 hybrid and is an open pollinated variety.  It appears that breeders selected plants with a generally uniform, compact, mounded plant habit and preferred to keep variation for color within their populations.  The result is mixed colors and relatively uniform plant size from both purchased and saved seed.

Penstemon ‘Lilliput Rose’


Penstemon ‘Lilliput Rose’ is also a clonally propagated, patented cultivar.  Although likely a perennial on other climates, it does not survive Minnesota winters.  There was surprising uniformity for flower color and plant characteristics between purchased plants of this cultivar and the seedlings.  Plants available for purchase were larger than our seedlings at planting time and throughout the growing season continued to remain ahead of the seedlings in development.  The data is a little misleading because of this.  Data was taken in July and then again in late August.  Number of flowering stems were substituted for number of individual flowers for the August data collection date because the number of individual flowers were staggering. Finding such uniformity among seedlings of a patented cultivar propagated by cuttings is very unusual.

Rudbeckia ‘Prairie Sun’


Rudbeckia ‘Prairie Sun’ is a very vigorous, attractive recent All-America Selections winner. Plants from the saved and original seed are very comparable.  This variety is likely not an F1 hybrid and is an open pollinated variety. Two of the eleven seedlings from the purchased seed were solid yellow and did not have the characteristic darker yellow petal base.  Two of the twelve plants from saved seed had flowers with tubular ray petals (typically called quilled petals in the case of chrysanthemums).  These plants are likely chance crosses with the variety ‘Radiance’ of rudbeckia which was planted next to the ‘Prairie Sun’ plants seeds were saved from. If kept in isolation from other rudbeckias, seedlings from saved seed of ‘Prairie Sun’ should be similar to those of purchased seed.

Petunia ‘Blue Wave’


Petunia ‘Blue Wave’ is an F1 hybrid.  Plants from purchased seed were far more vigorous, spreading much further and producing many more blooms than plants from saved seed. Surprisingly, flower color was very uniform among the plants from saved seed and comparable to the original variety, even though the plants the seed was collected from were surrounded by several other petunia cultivars in many different colors.  Although plants from saved seed were smaller, they were about the same height and a person could just plant seedlings more densely for a comparable effect. This may be an attractive option for gardeners, especially considering the price of F1 petunia seed and the fact that a lot of seed can easily be collected off of petunias.

Petunia ‘Baby Duck Yellow’


Petunia ‘Baby Duck Yellow’ is an F1 hybrid.  Just like ‘Blue Wave’, it came relatively true from seed for flower color.  Plants from saved seed were even more comparable to the original variety than ‘Blue Wave’ for plant size and flower number.

Ornamental foliage and fruit

Millet ‘Purple Majesty’


Millet ‘Purple Majesty’ is a very attractive purple-foliaged, ornamental grass.  Plants were very similar from purchased and saved seed.  There are awns that are part of the heads of grain, like wheat.  Among plants of the saved seed there was a single plant, interestingly, that segregated to not have awns. Just like the petunias and considering the cost of purchased seed of this All-America Selections winner, one may find it an attractive option to grow plants from their own saved seed.

Ornamental Chili Pepper ‘Black Pearl’


Ornamental Chili Pepper ‘Black Pearl’ is an F1 hybrid that has very attractive purple foliage and dark purple-black fruits that are round and upward facing.  Among the plants from saved seed, four of the twelve plants had green foliage and downward facing elongated fruit, while the remaining 8 plants had purple foliage and dark rounded, upward facing fruit like the original variety.  The parent plants the seed was saved from did not have other peppers nearby to cross with.  From the unique segregation for green foliage and downward, elongated fruit we can learn some interesting information.  All three of these traits appear recessive, simply inherited traits and since they all segregate together the genes governing them may even be on the same chromosome. One can easily germinate saved seed and save the purple foliaged ones and be pretty certain the fruit will be round and upward facing.  We tasted these chili peppers.  Wow, they were exceptionally hot!


Tomato ‘Juliet’


Tomato ‘Juliet’ is an F1 grape tomato hybrid and a recent All-America Selections winner.  The plants are indeterminate growers (the shoot tips keep growing, producing fruit throughout the season), ripening over an extended period of time.  The fruit is very sweet, firm, and delicious.  The plants from saved seed segregated widely for fruit shape, size, and flavor.  Some were very elongated, while others were round and small like cherry tomatoes.  The seedlings also segregated for indeterminate versus determinate plant habit (upper left and right photos, respectively).  Determinate plant habit means that all terminals end in flower buds and produce fruit that mature at a relatively uniform time, a trait common in commercially grown field tomatoes that aids in mechanical harvesting and processing. With nine indeterminate to three determinate plants from the saved seed, the data is consistent with indeterminate growth being dominant to determinate growth and the original ‘Juliet’ being heterozygous for the trait and a cross of parents differing for these traits.  At the Dakota County Master Gardeners Annual Picnic, we taste tested fruit from each of the individual 12 plants from saved seed, comparing their flavor to that of the original ‘Juliet’.  The flavor of the fruit from the original ‘Juliet’ plants was very uniform and sweet and pleasant. People thought for ten of the plants grown from saved seed the original ‘Juliet’ had better flavor, one plant received a tie, and one plant tasted better than ‘Juliet’. With the segregation for determinate versus indeterminate plant habit and fruit shape in the plants from saved seed it is suspected ‘Juliet’ may be a cross of a sweet cherry tomato (typically indeterminate in growth habit) and a firm fruited, elongated roma tomato (typically determinate in plant habit). With great variability for fruit size and a general reduction in fruit flavor among the plants from saved seed of ‘Juliet’, it may be wiser to purchase new seed in order to enjoy the full benefits of this superior hybrid.

From this demonstration we learned that for many plants, even some F1 hybrids, saving and raising ones own seed produces plants of acceptable or highly comparable quality.  The decision regarding if we save our own seeds or not and for which types of plants depends on multiple factors including: budget, degree of uniformity needed, and how much satisfaction and enjoyment one gets from the process.  For more informal garden designs where variability is actually a desirable feature in especially ornamentals, much more leeway can be had in saving seeds and utilizing the resulting seedlings.  For more formal designs where mass plantings of more uniform plants are needed and high quality vegetables with uniformity for flavor and other important traits, much less variability can be tolerated.  We welcome you to come and visit UMore Park this summer and see new comparisons between seedlings from the original, purchased seed and saved seed of a different set of varieties.

Bird-Nest Wasps

Jeffrey Hahn, University of Minnesota Asst. Extension Entomologist


Photo 1: Birds-nest wasp. Jeff Hahn

Several people have complained of insects damaging their windows and have either described or sent me samples of grass that they found in it.  When asked when they first encountered this, I was told that this was not new from the winter but had occurred last summer or fall.  When the samples were carefully examined, tree crickets were found amongst the grass.  People never noticed any other insects.

However, the tree crickets are not responsible for the grass.  The actually culprit is a sphecid wasp known as Isodontia.  This insect is called bird-nest wasp or grass carrying wasp.  It belongs to a group of sphecid wasps known as thread-waisted wasps.  They have a very thin stalk or waist (actually part of the abdomen) connecting the thorax with the abdomen.  The most common species in Minnesota is Isodontia apicalis.  It measures ½ - 3/4 inch long, is dull black in color, and is active from July to September.

A bird-nest wasp uses a preexisting cavity to construct its nest.  Worldwide, they have been known to use hollow plant stems, rolled leaves, abandoned bee nests, and even crevices between stones.  In Minnesota, home residents occasionally find them inside window cases.  The bird-nest wasp flies to her nest site, carrying grass, sometimes several inches long.  This grass is used to form cells in her nest.  She provisions her nest with insects to feed her young.  Isodontia prefers katydids or crickets - a particular species will prefer a specific insect as its prey.


Photo 2: Grass and tree crickets. Jeff Hahn

Although the activity of a bird-nest wasp can be a little alarming or disconcerting, they are not actually damaging anything.  Just remove the grass and insects you find.  It is unlikely you will have an ongoing problems with this wasp.  If you saw it one year, you probably will not see it the next.  This is fortunate as it would be very difficult to exclude them or otherwise control them.

Garden Calendar for March

David C. Zlesak


Photo 1: Spring flowering shrubs like forsythia have flowers that are ready to open once placed in a warm environment. Cut stems harvested now are easy to force into flower indoors.  David Zlesak

Are you ready for some spring blooms?  Consider cutting and brining in some stems for forcing of early spring flowering shrubs like forsythia, pussy willow, and flowering almond.  Stems of these shrubs have flower buds already developed and they are ready to quickly grow and develop in a warm environment after receiving their chilling requirement over winter.  Treat cut stems like standard cut flowers by changing the water frequently and using floral preservative.  Once the flowers begin to appear, their life can be extended by keeping them in a cooler portion of the house, out of direct sunlight, and away from drafts.

Continue to start seeds of bedding plants indoors at the appropriate time for each species.  Different species grow at different rates and the slower ones benefit from being started earlier so plants will be of good size when it comes time to plant them out after danger of frost.  March is a great time to start many bedding plants to provide them with about 8-10 weeks of growth before being transplanted outdoors.  Common bedding plants that would be great to plant in March include: dianthus, cleome, cole crops, hollyhocks (those that flower the first year from seed), peppers, petunias, rudbeckia (black-eyed Susans), and snapdragons.  Tomatoes grow very quickly from seed and can be started in late March or April for decent sized transplants in late May.  If one wants to get a jump start on the season with tomatoes and has the space to accommodate them, they can be started now.


Photo 2: Cutting this very overgrown shrub to the ground a few years back resulted in a flush of new shoots and a more manageable shrub. David Zlesak

March is a great time of year to prune many trees and shrubs.  Exceptions include species that tend to bleed heavily in spring like some maples and birch.  Spring is a great time to conduct rejuvenation pruning on many shrub species.  Rejuvenation pruning involve removing a small proportion of the oldest stems as close to the base as possible.  If one does this periodically (each spring or every other year) this will help keep shrubs producing new, strong stems that tend to be more vigorous, healthy, and flower better.  Extremely overgrown shrubs that have not been appropriately pruned for a long time can be cut completely to the ground as a last resort.  Most commonly, this technique results in a lot of strong growth from the base as there is a well established root system to support it.  Sometimes cutting an overgrown shrub completely to the ground may stress it out to such an extent that it may die or come back poorly at first. Spring flowering shrubs, like lilac and forsythia, are often pruned after they are done flowering so a season of flowering is not missed, although later pruning can add extra stress to the plant.

Sunday, February 1, 2009

What's Up With That?!

David C. Zlesak

wuwt_600px.jpg“Oh no, are my rhododendrons dying?” or something similar is a startling thought that comes to mind the first time many of us see this characteristic curling on leaves of our rhododendrons in winter. Fortunately, this is a normal response called thermonasty that actually helps our rhododendrons survive this difficult time of year. This curling and drooping of the foliage is in response to cold temperatures (thermo= heat or temperature and nasty= movement to a stimulus that is non-directional). As temperatures warm and cool during winter we can actually observe rhododendron leaves appearing less or more drooped and curled. As a broadleaf evergreen, the large surface area of rhododendron leaves makes them especially vulnerable to drying out during the winter. With the frozen soil this time of year, additional water cannot easily move up the plant and replace what evaporates from the foliage. Curling and drooping to prevent wind from reaching the undersides of the leaves, where stomates (openings for gas exchange) are typically more concentrated, can help prevent wind from drawing out as much moisture. In addition, many rhododendrons are native understory plants in deciduous forests. During the growing season the plants are shaded by the trees above, but during the winter when plants cannot utilize light well, leaves typically experience more intense sunlight capable of damaging exposed leaf tissue. Curling and drooping also aids the plant by reducing the overall amount of light intercepting a leaf. As we are excited for spring to come by this time of year in Minnesota, it might be fun for us as gardeners to look to our rhododendrons for a light hearted way to predict how much more winter we have left than groundhogs and how afraid they are of their shadows!

Hakonechloa macra ‘Aureola’ - 2009 Perennial Plant of the Year®

David C. Zlesak, University of Minnesota Extension Educator
Photo 1: Golden hakone grass has been a faithful perennial in this St. Paul garden for several years. David Zlesak

Since 1990, the Perennial Plant Association (PPA) has sponsored the Perennial Plant of the Year® program. Each year members select a superior performing perennial to highlight and promote. Nominations are made by members and winners are decided by ballot. Criteria for nomination includes it must perform well across a wide range of climates, be widely available and easy to propagate in order to supply demand, be relatively low maintenance and easy to grow so the average gardener has a high likelihood at being successful with it, and the plant displays ornamental appeal over a long portion of the growing season.

The 2009 Perennial Plant of the Year® winner is golden hakone grass (macra ‘Aureola'). The golden-green foliage and soft, cascading habit has made this shade tolerant perennial grass a favorite for years among gardeners. With a limited selection of ornamental grasses that are tolerant of shaded locations, golden hakone grass is a great addition. In these darker, shaded garden locations, the glowing, golden foliage easily stands out, often serving as a great focal point. Plants are clump forming, grow slowly, and do not need frequent division. In fall the foliage can take on pink and bronze tones.

The graceful, arching growth of hakone grass typically reaches a foot or so in height and is commonly used in group plantings or as a border plant with other perennial. It provides a great accent in texture and form and mixes nicely with other common shade-tolerant perennials like hostas. The foliage form is reminiscent of a compact growing bamboo making this grass a nice choice to include in Japanese gardens and gardens in general where one is trying to create an Oriental flavor. The small flowers golden hakone grass produces in summer are not readily noticeable. art2-2_600px.jpg

Photo 2: The foliage of golden hakone grass contrasts nicely with many other plants. Mary Meyer

The botanical name of this plant (Hakonechloa) is derived from the region in Japan where it is native (Hakon) and the Greek word for grass (chloa). It does best in moderately moist, acidic, well-draining soils high in organic matter and is adapted to openings in forests. Partial shade is best for this plant as full sun can cause some burning and lead to quicker drying out of soils. The deeper the shade, however, the greener the foliage color becomes.

Golden hakone grass is often listed as hardy to zone 5. However, many Minnesota gardeners in zone 4 have been successful with it. It has consistently survived year after year in many Minnesota locations without any special protection. Providing some insulation in more exposed locations and in zone 3 is recommended.

Besides Perennial Plant of the Year® winners, other great performing perennials tested as part of the University of Minnesota Annual and Perennial trials are featured at:

Past Perennial Plant of the Year® winners

2008 Geranium ‘Rozanne’ (not reliably zone 4 hardy)

2007 Nepeta ‘Walker’s Low’

2006 Dianthus gratianopolitanus ‘Feuerhexe’

2005 Helleborus x hybridus

2004 Athyrium niponicum 'Pictum'

2003 Leucanthemum 'Becky'

2002 Phlox panniculata 'David'

2001 Calamagrostis x acutiflora 'Karl Foerster'

2000 Scabiosa columbaria 'Butterfly Blue' (not reliably zone 4 hardy)

1999 Rudbeckia fulgida var. sullivantii 'Goldsturm'

1998 Echinacea purpurea 'Magnus'

1997 Salvia 'Mainacht' (May Night)

1996 Penstemon digitalis 'Husker Red'

1995 Perovskia atriplicifolia

1994 Astilbe 'Sprite'

1993 Veronica 'Sunny Border Blue'

1992 Coreopsis verticillata 'Moonbeam'

1991 Heuchera micrantha 'Palace Purple'

1990 Phlox stolonifera

The Winter View

Kathy Zuzek, University of Minnesota Extension Educator

art1-1_800px.jpgIt’s official. Winter is more than half over. Are you feeling a bit desperate for warm temperatures and the color green? I spend every February dreaming of a trip to anywhere warm and green or of a kinder, gentler Minnesota where spring actually arrives in February. A quick look out of my window though always reminds me of how truly bleak our long winters would be without woody plants.

Imagine our winters without trees. The word “tundra” comes to mind with endless unbroken landscapes and unchecked winter winds. In fact, the word tundra comes from the Finnish word “tunturri”, meaning treeless plain. Now add trees back into the picture and winter, even in February, is not so bad.

Leaves have fallen from deciduous trees and our focus turns to the sheer size and bold architecture of many tree species. White oak (Quercus alba), swamp white oak (Q. bicolor), bur oak (Q. macropcarpa), red oak (Q. rubra), northern pin oak (Q. ellipsoidalis), and black oak (Q. velutina) are native and abundant in Minnesota, and their large size and gnarled branches add interest to a winter landscape (Figure 1). Weeping willows (Salix sp) with their height and dramatic yellow weeping stems are startling against a blue winter sky (Figure 2). Who can help but notice a female Kentucky coffee tree (Gymnocladus dioicus) this time of year with its coarse branches, textured bark, and large seedpods (Figure 3).

Evergreen trees add mass and color to our winter landscapes. The view of large, mature white pines (Pinus strobus) and red pines (Pinus resinosa) against snow and bright blue winter skies in eastern or northern Minnesota is an amazing sight (Figure 4). In a planted landscape, spruce (Picea) and fir (Abies) lend a formal air with their conical “Christmas tree” forms (Figure 5). Scots pine (Pinus sylvestris) with its wide crown and horizontal orange branches provides a less formal source of green in winter landscapes (Figure 6). Austrian pine (Pinus nigra) with its stout trunks, branches, and dark green needles adds a strong sense of mass to our winter landscapes (Figure 7).

art1-2_800px.jpg Step in for a closer view of our winter landscapes and you will see texture and color everywhere. With leaves absent, the large flower buds on silver maple (A. saccharinum), red maple (A. rubrum), and Freeman maples (Acer x freemanii) give branches a beaded look. Nothing shouts texture like the cinnamon and ivory curling bark of a river birch (Betula nigra) (Figure 8), the flaky bark of three-flower maple (Acer triflorum) (Figure 9), the brown rustling leaves that are retained during winter on younger oak trees (Figure 10) or dried flower heads of hydrangea (Figure 11). The shiny red-brown bark of Manchurian cherry (Prunus maackii) (Figure 12) is beautiful on sunny or cloudy days. Dwarf conifers come in an amazing variety of form and texture in shades of green, blue-green, and gold (Figure 13). ‘Green Mountain’ boxwood (Buxus sp.), one of the few broadleaved evergreen plants hardy in Zone 4, is still a mass of green leaves in February (Figure 14). Many of our small trees and large shrubs are multi-stemmed plants whose twisting trunks and/or retentive fruit are full of texture and color: blue beech (Carpinus caroliniana) with its gray fluted stems (Figure 15), sumacs (Rhus sp.) with their red fruit (Figure 16), Amur maples (Acer ginnala) full of brown samaras (Figure 17), redbuds (Cercis canadensis) with seedpods, and tree lilacs (Syringa reticulata) with their masses of open brown seed capsules (Figure 18). We know crabapples (Malus sp.) for their beautiful and fragrant spring bloom, but many crabapple cultivars (‘Adams’, ‘Bob White’, ‘Centurion’, ‘David’, ‘Donald Wyman’, ‘Harvest Gold’, ‘Indian Magic’, ‘Ormiston Roy’, ‘Professor Sprenger’, ‘Red Jade’, ‘Red Jewel’, ‘Red Splendor’, ‘Sentinel’, ‘Silver Drift’, ‘Silver Moon’, ‘Sugar Tyme’,) retain their red, orange, and gold fruit through winter, adding color to gray winter days (Figure 19). European cranberrybush (Viburnum opulus) and our native American cranberrybush (V. trilobum), winterberry (Ilex verticillata), and barberries (Berberis sp.) also retain fruit through the winter. Masses of these vivid orange and red fruit are beautiful against a snowy backdrop (Figure 20). Red or chartreuse stems of our dogwoods (Cornus sp.) are another source of bright color during winter (Figures 21 & 22).

art1-3_800px.jpg Step up to trees and shrubs during your winter strolls for a bird’s eye view and more winter interest awaits you. Have you ever looked closely at the branches of our ornamental cherries, plums, and almonds? The branches and trunks of these plants, all of which are members of the genus Prunus, are often covered with conspicuous lenticels (Figure 22), openings that allow gas exchange between the inner parts of plants and the atmosphere. The green stem of a burning bush (Euonymus alatus) edged with brown corky ridges is full of interest (Figure 24)as is the colorful fruit of a bittersweet vine (Celastrus scandens) wrapping around a pillar (Figure 25). The blue or violet berry-like cones of junipers (Juniperus sp.) (Figure 26) and the cones of pines (Pinus sp.), spruce (Picea sp.), fir (Abies sp.), arborvitae (Thuja occidentalis), andDouglasfir (Pseudotsuga menziesii) against a backdrop of green needles or scales are full of color and contrast (Figure 27). How about the beautiful texture, color, and softness of a fur-covered Magnolia (Magnolia sp.) bud (Figure 28)? It’s almost as if each bud has its own winter parka. Look at the buds of lilacs (Syringa sp.). They are plump and green, appearing as if they will open tomorrow (Figure 29). The male flowers or catkins of birch (Betula sp.) trees and their relatives are visible all winter, providing a light texture in plant canopies (Figure 30).

art1-4_800px.jpg Look out across a vista, look up into a tree, or closely into a shrub and you will see that even in winter, our landscapes are packed full of interest. As you plan future landscapes, don’t forget to combine some of these plants into a collection of companion plants. Winter is a long season in Minnesota and a wise gardener plans for garden interest in winter as well as during our warmer months. The contrast of red dogwood stems, green pine needles, and oak leaves is a planting combination full of color and texture in winter (Figure 30) as is a grouping of ornamental grasses, and evergreens (Figure 32).

Escape Winter at the Arboretum’s Orchid Celebration in February

Tracy Walsh
Preview Event is Feb. 12; Exhibit Opens Feb. 13

art4-1_600px.jpgChaska, Minn. (Jan. 8, 2008) – Escape the icy blasts of winter and feast your eyes on some exquisite tropical beauties at the Minnesota Landscape Arboretum’s “Totally Orchids – Delight at First Sight” exhibit, opening Friday, Feb. 13, in the Arboretum’s Oswald Visitor Center.

The orchid show, presented by Orchids Limited of Plymouth and the Arboretum, will feature a wide array of unique species and select hybrids, all arranged in attractive planters on eye-level pedestals. The display will continue through March 8 and is free with gate admission ($7 adults).

Several complementary events are planned during the “Totally Orchids” exhibit. Check out these activities (all free with gate admission unless otherwise noted):

  • A special preview event, “Orchids Tropical Fantasy,” on Thursday evening, Feb. 12, from 5:30 to 8:30 p.m. will provide a first-glance at the orchid exhibit, plus a silent auction, mini-classes and orchid sales. Preview event tickets, at $35 each, also cover appetizers, wines and non-alcoholic drinks. Hosted by the Arboretum Auxiliary and co-sponsored by Orchids Limited. Reservations at or by calling the Auxiliary at 952-443-1400, ext. 7052.

  • Talks With Orchid Experts: 1-3 p.m. Saturdays & Sundays, Feb. 13-March 8, Visitor Center.

  • Orchid Plant Sales: Purchase orchids, orchid books, fertilizer trays and other supplies for orchid growing, Arboretum Gift Store.

  • Growing Orchids” class: March 1, 1-3 p.m., Oswald Visitor Center. (Call 952-443-1422.)

  • Orchid Symposium with the Orchid Society of Minnesota: Saturday, March 7, 10 a.m.-4 p.m. $35-$65, Oswald Visitor Center. Gain insight from the experts. (Call 952-443-1422.)

With over 28,000 species and more than 300,000 cultivars, orchids belong to the most diverse family of plants known to man. They are also extremely adaptable – growing in tundra, rainforest, desert and swamps. In fact, more than 45 types of orchids grow natively in Minnesota.

Fellow Gardeners—Start Your Seeds

Meleah Maynard, University of Minnesota Master Gardener

In February, as winter seems to drag endlessly on, gardeners who just can’t wait to feel some soil between their fingers finally have something to do: start sowing seeds. While many seeds need to be planted just four to six weeks before being moved outdoors, others that are slower to mature should be started 10 to12 weeks before being transplanted. Timing is important because you want your seedlings to be strong enough to manage on their own, but you don’t want them getting so big that they crowd each other and compete for light, water and nutrients.


Photo 1: Seed racks can be found this time of year at most garden centers. David Zlesak

If you haven’t already got a planting area set up in your basement or other cool, out-of-the-way place, you can easily do that now. Bright windows of course will do, but with the short days this time of year and often limited window space, lights are a great alternative. Be sure to find a spot near a power source so you can plug in lights and any heating elements you may need. Garden catalogs are full of seed-starting systems, but you can save money by building your own. I start my seeds on metal shelving I found at one of the big box stores. Shelving units are nice because multiple layers of plants can be grown in a particular space. art3-2_600px.jpg

Photo 2: Shelving systems allow for efficient use of space. Aluminum foil or other reflective material can be used against walls to help reflect light onto seedlings. David Zlesak

Fluorescent shop lights work great (you usually don’t need spendy grow lights) and can be suspended above each shelf from chains. The chains allow one to adjust the height of the lights as the seedlings grow. Generally, you want to keep them within a few inches of the tops of the plants once they have germinated. Florescent light is much less intense that sunlight and having the lights relatively close to the plants increases the light intensity. Keep lights on at least 14 to 16 hours each day to fuel strong growth. I find it’s easiest to just put them on a timer. Although you can keep lights on 24 hours a day, a dark period is useful to encourage plants to open and close their stomates to help them better acclimate when it comes time to transfer them outdoors. art3-3_600px.jpg

Photo 3: Regular florescent shop lights work great for young seedlings and can be put on automatic timers. David Zlesak

Plants need, in particular, the red and blue portion of the light spectrum in order to fuel photosynthesis. Cool white florescent bulbs tend to be rich in blue and borderline in red light. So some people like to mix warm and cool white florescent bulbs in order to get additional red light. This rich mix of red and blue light is what makes grow lights look purple. Bulbs differ based on wattage and lumens. The more lumens, the more light. The highest lumens you can typically find for four-foot T12 florescent 40-watt bulbs is about 3,200. Remember that because florescent bulbs contain a small amount of mercury, they are considered hazardous waste. Many cities have designated drop off sites and free disposal of florescent bulbs of all types. Several drop off sites are located in the metro (

People recommend all kinds of different containers for starting seeds, including trays and flats, plastic takeout containers, milk jugs, egg cartons. It really depends on personal preference and what works best with your set up. I like to use 12-ounce, clear-plastic cups (the kind you get for beer at a keg party—not that I go to those anymore). These take more growing medium than I would use in a shallow tray, but the advantage is that I don’t have to transplant the seedlings into larger, individual containers once they really start to take off. I just thin them out in their cups, leaving only one or two plants in each. art3-4_600px.jpg

Photo 4: Various sized and shaped containers can be used and a good germination mix to promote germination and avoid pathogen attack is recommended. David Zlesak

To start seeds, you want a growing medium that is light (to allow seeds to push their way up through it), porous (to allow proper drainage and aeration) and sterile (to preclude disease). You can buy soilless seed mixes or you can make your own using equal parts peat moss, fine perlite and vermiculite.

Seeds usually germinate best when the soil is warm and moist. Some seedlings need light to germinate while others don’t. Many can be put on top of your refrigerator or another warm spot until they germinate and then moved under lights to continue growing. (Windowsills aren’t a good choice, usually, because they can be cold and drafty this time of year.) Or you can purchase heating mats or cables to place under your plants in your prepared growing area. For most species, after the seeds germinate, it is good to reduce the temperature to help promote sturdy, compact plants. art3-5_600px.jpg

Photo 5: Garden centers often have a wide selection of seed starting supplies including heat mats, germination mix, and containers. David Zlesak

Directions on the back of your seed packets will usually tell you what you need to know, including how deeply seeds should be planted, how long until germination and whether the seeds need to be treated in any way before planting. These treatments, such as soaking seeds in water, scuffing the seed coat or placing them in a cold environment for several weeks before sowing, are often necessary for successful germination. If there is no recommendation for planting depth, the general rule is to plant seeds two or three times as deep as the seed’s diameter. Small seeds, such as poppy, snapdragon, and flowering tobacco, should be thinly scattered on top of the soil and very lightly covered, if at all. (Germination tips on a wide range of species can be found on this website: art3-6_600px.jpg

Photo 6: Plastic domes or baggies help to keep to retain high humidity during the germination process. David Zlesak

You’ll want to moisten your potting mix if it is dry before starting to plant. That way, when you water after planting the mix will easily soak up the moisture. As you sow your seeds, be sure to label each container. Trust me, if you think you’ll remember, you won’t. I’ve finally learned my lesson on that one. Once everything is planted, lightly mist the top of the soil with warm water and cover each container with plastic wrap or domes to help keep the seedbed humid and moist. Continue to mist plants, or water very gently, as needed. art3-7_600px.jpg

Photo 7: Labeling right away helps to keep track of what was planted. David Zlesak

Once your plants have emerged from the soil, you can begin to remove the plastic wrap (or plastic cover if you’re using the trays). Keeping seedlings covered will help to keep them from drying out so fast, but be careful the humidity isn’t kept too high. A lot of condensation can put developing seedlings at risk for attack by pathogens. I cover my cups with plastic wrap, leaving the sides somewhat open so air can get in. As plants grow, I use toothpicks or tongue depressors to keep the plastic away from the seedlings. Heating units can also be turned off at this point after germination is complete. If you germinated your seed without much light, remember to turn the lights on and keep them within a few inches of the plants to promote growth and prevent them from stretching. art3-8_600px.jpg

Photo 8: Higher light levels helps to prevent seedlings from stretching as in the case of this young petunia. David Zlesak

Check your seedlings regularly so they don’t dry out. Once your seedlings get their first few leaves (their first “true” leaves after the cotyledons), begin to feed them with a water-soluble fertilizer mixed at quarter strength once a week to help fuel strong growth. I like to use fish emulsion, though it is quite smelly. Soon the dreaded time of thinning will come. (I dread it, anyway) Though it feels like killing your darlings, you must thin the crowd in each seed container, leaving only one plant, maybe two, in some cases. Extra seedlings may be transplanted to new containers.

Finally, spring comes and your seedlings are almost ready for the garden. But, first, it’s best to help them get accustomed to outdoor conditions by helping them “harden off.” To do this, you’ll be taking the plants outside to a sheltered spot daily, a little longer each day. After a week or two, they’ll be ready to move to their new homes and you can take a few minutes to write down what worked and what didn’t so you’ll be ready for next year. The hardening off process allows the plants to adjust to higher light levels, wind, and temperature variations. If planted directly outdoors without hardening off, they can become sunburned or otherwise damaged.

Plant Type

Weeks needed between seed

sowing and frost-free planting date




12 or more








4 or less






12 or more









Pansy (Viola)

12 or more






4 or less




4 or less



The Right Time to Sow Seeds

When starting seeds, you want to sow them so they’ll be ready to plant after the threat of frost has passed, which is usually around Mother’s Day in Southern Minnesota and Memorial Day in Northern Minnesota. (Unless they are cold-tolerant plants, like pansies, which can go out earlier.) Typically very small seeded plants, such as begonias and snapdragons, need additional time for seedlings to develop in size because seeds do not contain much in energy reserves. Other plants just have a slower initial growth rate than others. Whether your seed packets lack the information you need to determine when to start your seeds indoors, or you’ve collected a bunch of seeds from plants you like and don’t know when to plant them, this chart offers sowing times for several plants gardeners often start at home.

Remove Fire Blight Cankers Now to Avoid Disease Problems in the Spring

Michelle Grabowski, University of Minnesota Extension Educator

Photo 1: Fire blight canker on a young apple branch. Michelle Grabowski

This past summer, many Minnesotans noticed dead brown wilted leaves on apple, crabapple and mountain ash trees caused by the bacterial disease known as fire blight (Read Midsummer Trouble for Trees & Shrubs) Although symptoms of fire blight are most apparent in spring and summer months, one of the best times to manage this disease is right now.

Fire blight is caused by the bacteria Erwinia amylovera. This pathogen can infect all members of the Rosaceae family, but most commonly causes problems on apples, crabapples, and mountain ash trees in Minnesota. In the spring and summer months, the fire blight bacteria infects leaves and blossoms, turning them black to brown. The infection often starts at the tip of the branch and moves systemically downward, resulting in entire branches that look blackened or scorched by fire. art5-2_600px.jpg

Photo 2: Discolored sapwood due to fireblight. Michelle Grabowski

It is within these infected branches that the fire blight bacteria survive Minnesota’s harsh winters. Branch infections are known as cankers and can be recognized by gardeners as an area of the branch with cracked, discolored and sometimes sunken bark. If the bark is peeled back with a sharp knife, reddish brown streaks can be seen in the light colored sapwood of the tree. Healthy sapwood should be off white to light green in color.


Photo 3: Fireblight canker on mountain ash. Michelle Grabowski

In addition it is common for the leaves and blossoms killed by a fire blight infection to remain attached to the infected branch. These are an indicator to gardeners to look more closely at the branch to determine where the branch canker is. Trees that suffered from fire blight in the previous summer should be carefully inspected for cankers regardless if leaves remain attached or not since wind can knock old leaves to the ground.

Any cankers that are found within the tree canopy should be pruned out and destroyed in February and March. During these months, it is too cold for the fire blight bacteria to be actively spreading within and between trees. In spring, as the weather warms up, however, the bacteria will multiply and ooze out of the canker in a sweet sticky liquid. This bacterial ooze is carried to new trees on wind driven rain, by insects, or on pruning tools and the hands of gardeners. It is therefore critical to remove branch cankers before the start of the new growing season to prevent new infections.

Gardeners should make the pruning cut to remove fire blight cankers at least 8 inches below visible signs of the infection. After each pruning cut, tools should be cleaned with a 10% bleach solution, rubbing alcohol, or a household anti-bacterial cleaner like Lysol® or Listerine®. All infected branches should be burned, buried or disposed of in the trash.

Does Cold Kill Bed Bugs?

Jeffrey Hahn, Asst. Extension Entomologist


Photo 1. Bed bug biting. Jeff Hahn

This has been one of the coldest winters in Minnesota in 15 years. And while it can be challenging to find many good things to say about this kind of weather, many people take consolation that the cold temperatures are good for killing insect pests. The most common question lately has been whether putting out furniture or other articles in very cold weather will kill bed bugs.


Photo 2: Fluctuating, cold temperatures may not reliably kill bed bugs. Jeff Hahn

Cold temperatures can kill bed bugs if they are exposed to it long enough and at temperatures that are cold enough. However, there is not a lot research on this topic to say what those exposures and temperatures are. What information is available is contradictory. One researcher in 1966 found that bed bugs can tolerate temperatures around 5o F for a brief time and when acclimated can survive temperatures at or below 32o F for days. This is in contrast to findings in 1991 that bed bugs are killed when exposed to temperatures around 32o F for just hours, although the same article also went on to say that the eggs are very cold tolerant and need to be exposed to freezing temperatures for 30 to 60 days.

There is even less research that looks at how long you need to freeze bed bugs when they are in furniture or other objects. The U.S. military believes that if you expose furniture to 0o F or less for four days or more, that may be sufficient. While we have been at or below 0o F often, those temperatures have generally fluctuated and have infrequently been sustained for four days or more.

There are other factors to consider. First, the temperature where the bed bugs are hiding may not be as cold as you think it is, i.e. the air temperature is not necessarily the same where the bed bugs are located in the furniture. You also need to factor in the effect of the sun shining on any objects. Although the temperature may say 0o F, the warmth of the sun can considerably raise the temperature in localized areas (as recently witnessed by the melting snow on my roof in near 0o F temperatures).

Again, cold can kill bed bugs, but the bottom line is you can not reliably kill all bed bugs infesting objects by exposing them to 0o F temperatures.

However, if you have or are concerned that you have items that are infested with bed bugs, keeping them outdoors will certainly immobilize any that are present until you decide what to do with them. If you have clothes, you can reliably kill bed bugs by washing or drying them at the highest temperatures allowed by the fabric. If you have other items you are not sure what to do with, contact an experienced pest control service for help in eradicating the bed bugs.

Low Maintenance Turfgrass Evaluation Study

Research Update - Low Maintenance Turfgrass Evaluation Study – A cooperative project between University of Minnesota Extension and Hennepin County Environmental Services

Bob Mugaas, University of Minnesota Extension Educator art7-1_600px.jpg

Photo 1: Site conditions prior to low maintenance turfgrass installation, spring 2006. Bob Mugaas

Following is a brief report summarizing the results and observations regarding the establishment and growth of selected fine and tall fescue grass cultivars on an environmentally harsh site. It is located in Spring Park, Minnesota on the shores of Lake Minnetonka. Specifically, it is a nearly fully exposed south facing shoreline embankment between the Lake Minnetonka Sheriff’s Water Patrol (SWP) building and the Spring Park public access (PA). The southerly exposure and very poor, sandy to gravelly soil make this an intensely hot and very dry site. There exists a small lilac hedge along the very top (north) edge of the area adjacent to the parking lot. There are also several, poorly formed crabapple, green ash and Russian olive trees located on this site. All are less than 20 feet in height. Information regarding the establishment, longevity and competitiveness of these grasses on this site should be helpful to others managing similar types of sites.

This project was a cooperative effort between the Hennepin County Department of Environmental Services and the University of Minnesota Extension. Project managers from Hennepin County were Anthony Brough and Greg Senst. Regional Extension Educator, Bob Mugaas from University of Minnesota Extension, served as principal investigator for the study with cooperation from University of Minnesota Department of Horticulture Faculty member in turfgrass science, Dr. Eric Watkins.

Nature and Purpose of the Study:

Following several unsuccessful attempts to establish permanent, perennial, non-turfgrass vegetation on the above described site, the Hennepin County Department of Environmental Services contacted University of Minnesota Extension for advice and possible assistance in attempting to establish a very low maintenance turfgrass type groundcover on this area. From that request evolved an applied research/demonstration project evaluating whether or not a commercially available no-mow mix of several different fine fescue varieties could successfully be established and maintained on this site. The individual fine fescue varieties contained in the mix would also be evaluated independently in separate plots to assess their individual performance and potential contribution to the success (or failure) of the no-mow mix. Also included in the study was a seeded and sodded example of tall fescue. Seed for the no-mow mix along with the individual fine fescue cultivars and the tall fescue blend was generously donated by Twin City Seed Company. The rhizomatous tall fescue sod was donated by Glen Rehbein Companies. These industry contributions to the project were greatly appreciated.

Project Design and Installation

The specific varieties contained in the no-mow mix were ‘Defiant’ – hard fescue, ‘Celestial’ – creeping red fescue, ‘Intrigue’ – chewings fescue, and sheep fescue for which a variety was not specified. The tall fescue blend included the varieties ‘Millennium’, ‘Aztec II’, and ‘Anthem II’. The sodded cultivar is simply known as Rhizomatous Tall Fescue (RTF). With the exception of the sodded tall fescue, all other varieties were direct seeded April 25, 2006. The RTF sod was installed May 9, 2006. Plot sizes for the individual fine fescue cultivars and the tall fescue plots ranged from 400 to 600 square feet. The area seeded to the no-mow mix was about 1200 square feet in size. Once seeded, all areas were covered with Futerra™ erosion control mats to provide for a more uniform seed germination environment and help prevent soil erosion.

Turfgrass evaluation of the plots included both pictures and notes regarding establishment success, as well as color, density and overall quality of the planting as observed at various times during 2006 and 2007. Ultimately, information regarding the establishment, longevity and competitiveness of fine and tall fescues on very difficult sites was obtained and should be helpful to others considering use of the same plant material in similar situations.

Due to the very hot dry conditions during spring and early summer of 2006, regular watering was provided to ensure adequate moisture for germination and early seedling growth. Watering frequency and amount was significantly reduced during July, 2006 and eventually eliminated during August, 2006. Again, this practice was adopted in an effort to move toward minimal maintenance inputs on this site.


Photo 2: Two weeks following seeding. Note fine fescue seedlings growing through Futerra™ erosion control mats. Bob Mugaas

As this was a spring seeding, the potential for annual weeds to germinate, grow and potentially outgrow and out-compete the desirable grasses was high. Hence, regular mowing at about 3.0 to 3.5 inches was carried out through the middle of August, 2006 in an attempt to provide some level of weed suppression without resorting to the use of an herbicide. No further mowing was done on this site for the duration of the observation period as the ultimate goal was to have this be a no-mow area. An application of a broadleaf herbicide in the fall of 2006 was used to control developing perennial broadleaf weeds. No additional herbicides for either annual or perennial weeds were used in 2007. A turfgrass starter fertilizer was applied at the time of seeding. Also, plots did receive an application of nitrogen fertilizer at the rate of 1 pound of N per 1000 square feet in late October of both 2006 and 2007.

Results and observations summary

Futerra™ mats provided good protection from soil erosion and likely contributed to better initial establishment through greater uniformity of the seed germination environment. Supplemental irrigation can be extremely important in the early growth, establishment and even survival of spring seeded turfgrass. It can also be a means of moderating the effects of high temperatures. In this instance, the consistent watering provided by Hennepin County staff allowed for uniform germination and early growth of the seedlings thereby getting them off to a good start in spite of the prevailing hot, dry conditions during late spring and early summer. Where irrigation cannot be provided, the use of erosion mats such as those used in this study may play an even more important role in successful early turfgrass growth and establishment, especially for spring seeding.


Photo 3: Two months following seeding and before any significant summer drought stress. Foreground is the tall fescue seed blend with fine fescues behind. Bob Mugaas

Given the harsh conditions of poor soil and extreme exposure on this site, the fine fescues under a no-mow situation performed acceptably well and could be considered a good choice for providing soil stabilization and an appealing look to the area. However, one notable caveat is that in the full sun exposure of the southernmost 1/3 to 1/2 of the plots, some dieback of the fine fescues did occur. This was most likely due to the combination of high temperatures and dry conditions. This amount of injury would likely create the need for overseeding in order to preserve turfgrass density and limit future weed encroachment. For the purposes of this study, overseeding was not performed.


Photo 4: Poor recovery and growth due to heat and drought stress injury to fine fescues occurring during the summers of 2006 and 2007. Note healthier condition of fine fescue in partially shaded areas. Picture taken 8-31-07 Bob Mugaas

Where plots included some partial shading of the fine fescues, their performance was significantly better than on the more open, exposed portions. That observation is consistent with previously known information about fine fescues and reaffirms their successful adaptation to drier, partially shaded areas of the landscape (please see the last photo in the article).

In an effort to keep annual broadleaf weed competition from becoming excessive, mowing at about three inches was utilized during the early establishment period. Even though mowing heights were kept as high as possible, the extent of root development may still have been limited and perhaps contributed to the plant’s inability to survive the very hot dry conditions experienced from late spring through mid-summer of 2006.


Photo 5: Spring and early summer growth in 2008. Note the lack of flowering shoots (culms) in the shaded areas compared to those in full sun. Bob Mugaas

Because mowing is known to negatively impact turfgrass rooting, it may have been better to minimize or even eliminate mowing on this site and use an herbicide to manage potentially excessive weed competition early in the establishment period. This would have allowed the development of a deeper, more robust turfgrass root system and perhaps provided better tolerance, even survival, of the environmental stresses posed on this site. Hard fescue and sheep fescue are known to have very good to excellent drought tolerance and would be expected to survive and grow in relatively harsh conditions. However, all four of the fine fescue species/cultivars used in this study experienced difficulty in maintaining acceptable turfgrass density and growth where not partially protected by filtered shade from trees.

In addition to the mowing, there were relatively high levels of Canadian geese feeding on the lower two-thirds of most plots during the late summer and fall periods of 2006. Again, that kept plant heights very short, well below the three inch mowing height in some parts of the plots, and hence would likely had a negative impact on turfgrass rooting depth especially during the active root growth period of early to mid fall for our cool season turfgrasses. While all plots experienced at least some degree of geese feeding, it did appear to be less on the two tall fescue plots.


Photo 6: Acceptable to above average growth and recovery of seeded tall fescue plot during same time frame as in the fourth photo in this article. Picture taken 8-31-07. Bob Mugaas

The seeded and sodded tall fescue plots performed remarkably well with respect to their ability to tolerate and recover from hot dry conditions. Also, there appeared to be little overwintering injury due to lack of hardiness; a problem previously limiting the use of tall fescues in this region. In addition, there did not appear to be any particular advantage of using tall fescue sod versus seeding tall fescue under a Futerra™ erosion control mat. Ratings on all characteristics were similar throughout the course of the study.

There are many instances where poor site conditions create extremely difficult conditions for establishing any type of vegetative cover, including turfgrass. Results and observations from this study indicate that the use of fine fescue turfgrass species as well as certain varieties of turf-type tall fescue under no-mow practices could make acceptable or better plant material choices than what is typically used for these conditions. While both survived quite well in partially shaded conditions, the slightly lower temperatures along with reduced sunlight intensity clearly benefited the survival and growth of the fine fescues to a greater extent than the turf-type tall fescues. Future projects should continue evaluating turf-type tall fescues and fine fescues in these difficult environments. In turn, this will continue to build the data base of successful turfgrass species and essential cultural practices needed to establish low maintenance turfgrasses on these difficult sites near shorelines.

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