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Saturday, January 31, 2009

Garden Calendar for February

David C. Zlesak


Photo 1: With increasing light levels, houseplants can use more nutrition. David Zlesak

Continue to the planning process for your 2009 garden. As you decide the plant materials you would like to have this season consider how you will obtain these plants. Some may not be readily available and you will need to start them from seed soon or orders should placed soon for seed and nursery stock to help ensure you get what you want. Many catalog suppliers have discounts or other incentives for those that order early.


Photo 2: Being welcomed home on a winter day by the smell of spring bulbs is a glorious experience. David Zlesak

As the days get longer and light intensity increases, consider starting to fertilize houseplants again. It is important to read and follow directions carefully. Different fertilizers have different concentrations of nutrients in them which can lead to different application rates. Also, fertilizer formulation is an important factor because that can influence how fast it dissipates, how readily the nutrients are available to the plants, and how often it should be applied. Again, take the time to read and then follow the directions. As light increases this time of year, so does the potential for photosynthesis and ultimately growth. It is important to recognize that fertilizer does not provide plants with energy, but building blocks for growth. These elements are assembled to build tissue for growth from the energy captured from light via photosynthesis. It is important not to overfertilize plants because buildup of unused fertilizer can damage plants.

Bring a preview of spring into your home with forced bulbs. If you haven’t potted some spring flowering bulbs for forcing yourself, they can readily be purchased from garden centers. Purchase potted bulbs that have not opened yet and keep them in a relatively cool spot in the house to help extend the impressive show.

Thursday, January 1, 2009

What's Up With That?!


David C. Zlelsak

As eastern white pines (Pinus strobus) mature, they tend to develop a rounded upper canopy and interesting asymmetric form to their branches. The interesting branch arrangement, providing rich character to these trees, is due in part to how they have adapted to handle the stress imposed by the weight of snow and ice. The generally horizontal branches of white pine are somewhat brittle, and as they become excessively weighted down, especially in the presence of heavy winds, they respond by snapping and collapsing to the ground. The straight trunk typically remains in tact, helping to keep the tree standing tall. It’s impressive to see forests in Minnesota and Wisconsin where mature eastern white pines typically tower over neighboring tree species.

Photo 1: David Zlesak

The Moth Orchid Takes Off!

Christopher Currey University of Minnesota Graduate Student

Moth orchids (genus Phalaenopsis) have been taking the potted plant world by storm for the last decade. They are now second only in total sale value to poinsettias, yet per pot they are the most valuable crop on the market today. The advent of advanced tissue culture and production methods has brought the plant out of the elite Victorian glasshouse to the shelves of nearly every retailer, allowing them to become the most accessible orchid on the market today. Combine this accessibility with their ease of growing in the home environment and you have a wonderful, rewarding tropical orchid for the everyday home gardener.


Photo 1: Phalaenopsis orchids are a commonly sold in box stores to upper scale garden centers. David Zlesak

Name, nomenclature, etymology

The genus Phalaenopsis received its name in 1825 from the Dutch botanist Blume. The common name, the moth orchid, reflects the Greek etymology behind the scientific name: phaluna, moth, and -opsis, resembling. This is in reference to the moth-like blossoms produced on long spikes. There are currently 63 distinct species, with numerous subspecies and hybrids found in nature, not to mention the countless crosses made by hobbyists and professionals world wide.


Phalaenopsis plants are fairly easy to identify when in bloom. Flowers in the genus have a broad diversity in color among the species, with smaller variation in shape. There white and pink flowers that resemble the commercial varieties seen most often, yet there are also yellows, purples and even some green ones that are solid or decorated with stripes or bands. The distinct inflorescence is comprised of flowers borne in numbers from few to many on a stem arising from a leaf axil. In fact, when a flower stem first starts to appear, it is difficult to distinguish it from the roots of the plant, which also arise from leaf axils.


Photo 2: The flowers of Phalaenopsis orchids is reminiscent of moths. David Zlesak

The roots are another distinguishing part of the plant. Thick green or purplish roots with a spongy white coating often protrude out of the pot and grow in the air. It is quite common for people to be worried about this when they initially start growing the plants and see these roots produced! The roots are perfectly fine growing outside the pot like this, as it is part of their natural plant habit. In their native environments Phalaenopsis plants are either epiphytes or, less commonly, lithophytes growing on plants or rocks, respectively. These roots grow out and act as anchors and attach to other plant material or rocks, while absorbing moisture and nutrients in addition to acting as photosynthetic organs!

Finally, although the leaves of these plants may not seem as attractive as the flowers, they can serve as an attractive foliage plant when out of bloom. Most species and commercial varieties in the genus have an average of five or six leaves from six to twelve inches in length and around four or five inches wide. The leaves are often shiny or leathery in appearance and plain green or purple with some white mottling. One aspect of the plant that is worth noting is the lack of pseudobulbs that many other orchids have. For this reason, Phalaenopsis were particularly prized in the 1800’s. When ships would cross oceans filled with plant material bound for Europe, plants with pseudobulbs would have greater success upon reaching their destination, while moth orchids had no storage organs and would not ship as well until advances in shipping technology were made.


Photo 3: Although the flowers are typically prized more than the foliage, the foliage can be quite attractive. David Zlesak

Native Environment (geographic/environment)

Phalaenopsis is a genus of from tropical regions in the Old World. The range is throughout tropical Asia east to the Philippines and west to Sri Lanka. In these tropical regions the plants grow in habitats that experience either seasonal drought, seasonal periods of cooler temperatures, or constant moisture/humidity. This is one reason that the plants are quite versatile and suitable for growing in the home, as these environments are easy to recreate by combining natural changes in the season and cultural practices.

Culture and Environment


When potting moth orchids, the choices of different potting media can be staggering. There are numerous commercially-offered media, and the number of “recipes” for custom-mixed media rivals the number of dubious remedies some popular authors have for keeping plants healthy. In reality, Phalaenopsis are quite amenable to any growing medium, as long as cultural conditions are adjusted to suit the medium. I have even heard anecdotes of people growing moth orchids in shredded tires and socks! The two most common media for moth orchids are long grain Sphagnum moss or a standard bark-based mix containing bark, charcoal, peat, and perlite. When potting with a bark-based mix place the bare-root plant in the container, fill in and around the roots with the mix and press the medium in firmly around the roots. When using sphagnum, loosely place the moss around the roots while not packing or compressing the fibers.


Photo 4: This porous product gaining in popularity as an orchid medium is a form of baked clay. David Zlesak

A variety of containers may be used for potting Phalaenopsis orchids. A true classic, unglazed terra cotta or clay pots have been used many decades. Benefits include increased aeration and weight, causing increased gas exchange and a heavy base to support the plants, respectively. Drawbacks are an increase in salt accumulation, difficulty in sanitization and breakage. More commonly used today, plastic pots are perfectly suitable for orchids. While they are lighter and are not as porous, they are easier to sanitize and reuse and do not accumulate excess salts from water or fertilizers. One aspect to take into consideration when selecting plastic pots is the color. As mentioned earlier, Phalaenopsis roots may absorb water and nutrients, but they will not do this unless they are in contact with the potting medium. When clear plastic pots are used, more roots grow down into the medium, whereas when pots are used that do not transmit light the number of aerial roots will increase.


Photo 5: Moth orchids come in many colors and color combinations. David Zlesak

An alternative to potting, some species of Phalaenopsis with pendant inflorescences are well-suited to mounting. This may is easily done by taking a slab of tree fern or cork that has been sterilized and a layer of damp long-grain sphagnum moss on it below where the plant will be placed. Next, place a bare-root plant on top of the sphagnum topped with another thinner layer of moss. Finally, tie the plants and moss down to the mounting material using fishing line. This provides an attractive alternative to potting. However, care must be taken with these plants to not let them dry out. They will need more frequent watering as there is not much media to hold moisture over a longer period of time.


Moth orchids vary in their feeding requirements. When growing species you may feed at every watering using 1/4-1/2 teaspoon of a balanced water soluble fertilizer per gallon of water applied during the active growing season. Feeding frequency and strength may be decreased to every other or every third watering with a maximum of 1/4 teaspoon fertilizer per gallon of water applied during the winter months when vegetative growth will not be as vigorous. Alternatively, the commercial hybrids may be grown with more feeding year-round without a seasonal break under optimum light and other growth conditions. Using 3/4 - 1 teaspoon of a balanced water soluble fertilizer per gallon of water applied is recommended for hybrids growing under more optimal conditions, combined with a clear-water leaching every fourth watering.


Photo 6: Careful pruning of flower spikes can encourage side branches and additional flowers. David Zlesak


Phalaenopsis grow fine in the temperature range experienced in the home environment. Temperatures ranging from the lower 60’s to the higher 70’sF are suitable for growing these plants. The air temperature is also key for initiating flower production. Maintaining the day and night temperatures below 80°F (preferably in the 60’s) for three or more weeks will allow flower initiation to commence. This can be easily done by having the plant placed next to a window during the winter where the temperature may be cooler than the rest of the room. After a while you will see the beginning of an inflorescence coming out of one or more of the leaf axils. This will take a while to develop, yet it will be well worth the wait. A single flower on a moth orchid may last around a month, so a stem with multiple blossoms may be blooming for months! When the plant has finished blooming, do not be in a hurry to chop the stem back. Wait a few weeks and cut the stem back about a half inch above where it turns from green (live) to brown (dead). This will result in branching and more flowers, quite an impressive sight.


Light levels suitable for growing Phalaenopsis ranges from 1,000-3,000 foot candles. You can achieve these levels in the home by growing plants in north, east or shaded west windows. In the summer, plants may be placed outdoors underneath lathe or shade from trees.

Winter Carnival Orchid Show


Escape to the Tropics January 24 & 25, 2009

During the Saint Paul Winter Carnival, winter and all it's glory, snow, ice and frigid temperatures, are celebrated. One event stands out and gives attendees a way to escape to the tropics without even getting on a plane, the Winter Carnival Orchid Show at the Marjorie McNeely Conservatory January 24 and 25.

Hundreds of orchid plants owned by individual and commercial orchid growers transform the Marjorie McNeely Conservatory into a tropical wonderland where instead of King Boreas, orchids rule. Besides witnessing the beautiful plants and displays, vendors will be offering plants and other wares.

The Orchid Society of Minnesota and the Marjorie McNeely Conservatory work together to exhibit the largest display of privately owned orchids in the region. The Winter Carnival Orchid Show is an American Orchid Society (AOS) judged event. Orchid judges from throughout the Midwest travel to Saint Paul to bestow awards and points.

Orchids are the largest family of flowering plants. One of the oldest and best organized of plant hobbies, orchid culture now enjoys worldwide popularity. Their incredible beauty and diversity captivate men and women of every walk of life.

The Winter Carnival Orchid Show will be held on January 24 and 25 at the Marjorie McNeely Conservatory at Como Park Zoo and Conservatory in Saint Paul from 10am to 4pm. Admission is $5 for adults and $3 for children 12 years and younger.

Como Park Zoo and Conservatory Background

For over 100 years, Marjorie McNeely Conservatory and Como Zoo in Saint Paul, Minnesota has charmed, educated and entertained millions of children and adults, while fostering an appreciation of the natural world and helping to make Saint Paul the Most Livable City in America. The Como Park Zoo and Conservatory is open 365 days a year; 10am-6pm from April-September and 10am-4pm from October-March. Admission to both the Como Zoo and Marjorie McNeely Conservatory is always free and a voluntary donation is appreciated.

For more information, visit

2009 All-America Selections Winners

David C. Zlesak, University of Minnesota Extension Educator

All-America Selections (AAS) serves as the oldest (first award winning varieties were designated in 1933), most established, impartial international testing organization in North America. Breeders from around the world enter their best flower and vegetable seed varieties with the hope that their entries would prove themselves to be superior performers across the 46 trial gardens in the United States and Canada and earn this prestigious award. Performance of test varieties are compared with the best commercially available varieties of their class. In addition to the trial gardens, there are display gardens which feature recent and next year’s AAS winners. All together there are 176 AAS display gardens. The five AAS display gardens located in Minnesota are listed at the end of this article. Seeds and transplants of new AAS winners are widely available from leading garden centers and seed catalogs.


Photo 1: Viola ‘Rain Blue and Purple’ All-America Selections

The four AAS winners for 2009 are:

Viola ‘Rain Blue and Purple’ comes in shades of purple, blue, and white. The 1.5” blooms typically open purple and white and darken as they age to a mixture of purple and blue providing a mixed tapestry of monochromatic color. While typical violas will stop flowering in the heat of summer, this one possesses above average heat tolerance and will continue to grow and bloom more reliably. Plants typically grow to 6” in height and spread 10-14” in width. It makes a great low border plant or container plant where it can spill over the edge of containers.


Photo 2: Melon ‘Lambkin’ All-America Selections

Melon ‘Lambkin’ has fantastic flavor! The white flesh is juicy, sweet, and very aromatic and the rinds are thin. Compared to other gourmet melons of the “Christmas type”, this one ripens relatively early at 65-70 days. Plants are vigorous and productive. Melons are oval shaped, two to four pounds, and once mature have a yellow rind color with green mottling. They have great storage compared to other melons when kept cool in a root cellar or refrigerator as well.


Photo 3: Acorn squash ‘Honey Bear’ All-America Selections

Acorn squash ‘Honey Bear’ has a deliciously sweet, honey-like flavor when cooked. Compact plants are high yielding due in part to their great tolerance to powdery mildew, a disease that can stress other acorn squash varieties and result in minimized yield and delayed maturity. Fruits are about a pound in size, a perfect size for and individual serving or sharing between two people. The rind is a very attractive dark green and the flesh is a rich deep golden color. Fruit matures in approximately 100 days,


Photo 4: Eggplant ‘Gretel’ All-America Selections

Eggplant ‘Gretel’ is an exceptional early fruiting, white skinned variety. Days from transplant to first ripe fruit is 55 days under good growing conditions. Fruit are borne in small clusters and the flavor is noticeably sweet and the skin is tender. These exceptional fruit quality characteristics allows fruit to be harvested beyond the optimum size of 3-4” in length and still retain good eating quality. Plants are relatively compact, reaching a height and width of about 3’. This is a great eggplant for those that only have a small area able to devote to vegetable gardening or for container growing.


Photo 5: U of M West Central Research and Outreach Center. David Zlesak.

To view many new flower and vegetable varieties, visit the five AAS display garden sites in Minnesota:

U of M North Central Research and Outreach Center
1861 Hwy. 169 East
Grand Rapids, MN 55744

U of M West Central Research and Outreach Center
46352 State Highway 329
Morris, MN 56267

U of M Display and Trial Garden
Corner of Gortner and Folwell Avenue
St. Paul, MN 55108

Minnesota Landscape Arboretum
3675 Arboretum Drive
Chaska, MN 55318

Lyndale Park Gardens
4125 E. Lake Harriet Pkwy.
Minneapolis MN 55409

Minnesota Green Expo 2009 at the Minneapolis Convention Center January 7-9, 2009


Photo 1: The Minnesota Green Expo will have hundreds of vendors representing a wide diversity of products. David Zlesak

The Minnesota Green Expo is one of the largest Horticulture Expos in the nation. It is geared towards all sectors of the Horticulture/Green industry (arborists, florists, nurseries, greenhouses, landscapers, turf specialists, groundskeepers, etc.). It is a wonderful opportunity to learn through educational seminars, networking, and seeing new products at the huge tradeshow where regional, national, and international vendors are represented. Many nurseries have forced into growth and flower their new and recent cultivar releases and landscapers have beautiful displays demonstrating their products and skills.

The Minnesota Green Expo is hosted jointly by the Minnesota Turf and Grounds Foundation and the Minnesota Nursery and Landscape Association. Although geared towards conveying information and highlighting products for industry professionals, it is a great opportunity for everyone who loves horticulture and wants to learn about the latest issues and products. To learn more, please visit: There are a lot of options to come and participate. One can purchase a three day complete registration (open to educational seminars and tradeshow), single day registration (open to educational seminars and tradeshow for the particular day), or tradeshow only access. With the event soon upon us, one can take advantage of the opportunity to just register at the door. The most affordable way to participate in this event is Friday only tradeshow access for $5.

Tree Care Advisor Core Course 2009


Mark your calendars for the 2009 Tree Care Advisor Core Course in St. Paul, Minnesota! Training includes education on several topics including: tree identification, plant selection, basic physiology and morphology, soils, site analysis, firewood identification, diagnosis of disease and insect problems, pruning, planting and more. These trainings are geared towards individuals who may not know much about trees but do know they want to learn.

The Minnesota Tree Care Advisor program has been training tree stewards (TCAs) for communities since 1993 and since that time TCAs have contributed over 50,000 volunteer hours to Minnesota communities.

Who should attend?

Green industry professionals, Master Gardeners and those folks who have the desire to learn about trees and take that learned information and share it with others in their community.

When are the trainings?

  • March 14, 8:30- 3:30

  • March 21, 8:30-3:30

  • March 28, 8:30-3:30

  • April 4, 8:30-3:30

  • April 18, 8:30-3:30

Where are the trainings taught?

Green Hall, Room 230
University Of Minnesota, St. Paul Campus,
1530 Cleveland Ave. N.
Saint Paul, MN 55108

How much does the training cost?

  • For volunteers, $95 (with an expectation of 50 hours of volunteering)

  • For professional track, $375 (with no volunteer requirement)

  • Includes 5 days of speakers, training manual, coffee and good conversation…

How do I apply?

Print and mail-in application form found at:

Who can I contact for more information?

Dave Hanson,Phone: 612-624-1226, E-mail:

Initiation of the Northern EarthKind™ Rose Trials

David C. Zlesak, University of Minnesota Extension Educator

In the spring of 2007 the Northern EarthKind™ Rose Trials began. There are literally dozens of old and new roses touted as being superior low-maintenance landscape performers for our region, but many do not routinely live up to these claims. As we read the advertisements, it is hard for us as consumers to find landscape roses at the garden centers not being described as hardy and disease resistant. The goal of this effort is to identify the most consistently beautiful, low-care, pest tolerant roses for our region through putting them through multi-year, multi-site trials under a typical landscape environment.

In the spring of 2007 the Northern EarthKind™ Rose Trials began. There are literally dozens of old and new roses touted as being superior low-maintenance landscape performers for our region, but many do not routinely live up to these claims. As we read the advertisements, it is hard for us as consumers to find landscape roses at the garden centers not being described as hardy and disease resistant. The goal of this effort is to identify the most consistently beautiful, low-care, pest tolerant roses for our region through putting them through multi-year, multi-site trials under a typical landscape environment.

Photo 1: Regionally-adapted rose cultivars that thrive without excessive care exist, such as these plants of ‘John Davis’ (left) and ‘John Cabot’ (right) in St. Paul. The goal of EarthKind™ is to scientifically identify and endorse the best of them. David Zlesak

When I started as an Extension Educator in 2006, I knew a little bit about the EarthKind™ program started at Texas A&M and their work with roses in the South. The EarthKind™ program combines both research and extension/education. I was impressed with their program and called to see if there was a way we could begin a branch of EarthKind™ following similar principles in the north. To my delight, they were just as excited about the possibility as I was. In January 2007 the EarthKind™ team invited me down for a day long EarthKind™ symposium in Houston. I joined a group of about 100 Master Gardeners, rosarians, and people just passionate about plants for this wonderful series of educational sessions devoted to all aspects of EarthKind™ (it includes multiple components to support environmental stewardship of the ornamental landscape) and toured some of the research sites. Conveying this experience with the University of Minnesota Extension Horticulture team, we knew this was something we wanted/needed to be a part of. They had a strong foundation and growing national recognition, and partnering with them in this important research instead of trying to start a completely independent effort would be the best use of limited resources. Before going into specific details about the Northern EarthKind™ Rose Trials and other exciting opportunities we have to expand into herbaceous perennial and shrub trials, I would love to share with you highlights of the history of EarthKind™ and a general overview of the program.

Photo 2: The day long EarthKind™ Symposium hosted in Houston, Texas in January of 2007 introduced me to EarthKind™ team members and gave me a great overview of the program to convey to University of Minnesota colleagues. David Zlesak

Background of EarthKind™

In the early 1990’s scientists at Texas A&M University initiated EarthKind™, a program serving as an umbrella for research-based information regarding sound environmental stewardship of the ornamental landscape. At this time the need for tested information to help answer questions of people interested in more sustainable practices were growing and there was limited data on which to base recommendations. Dr. Steve George, the founder of EarthKind™, and a handful of colleagues began this huge task with their limited resources to begin to address these questions for those they served in the state of Texas. Rose cultivar trials, soil health and nutrition, and turf management were some of the areas they initially focused their attention on.

They recognized there was a need for this kind of information in context of regional environmental conditions beyond the citizens of Texas and the program expanded. The program has since expanded throughout the United States and some additional countries (Canada, Bermuda, India, and New Zealand). The mission is to provide all sectors of the horticulture industry (i.e. consumers, nurseries, landscapers, municipalities, retailers, etc.) with regionally appropriate, trustworthy, cutting-edge, research-based information regarding environmental stewardship of the ornamental landscape. With all the connotations, contention, and diversity in definitions surrounding recognizable terms like sustainable and organic, the new and straightforward term EarthKind™ was coined by Dr. Steve George. The goal is to use the most kind practices to the earth as possible as we identify plants and management systems that still preserves the general vision of what people deem as an acceptable landscape so it will be implemented and have impact. The EarthKind™ approach can be applied to all facets of the landscape: ornamentals, turf, vegetables, and fruit. Areas of emphasis that started the program and continue strongly include 1). identifying soil and nutrition management strategies which are low input, effective, and recycle nutrients from municipal yard waste thus reducing pressure on overcrowded landfills, 2). identifying regionally-adapted plant materials which perform well under local climatic conditions, and 3). increasingly methods and plant materials that help to conserve limited water resources.

Photo 3: Dr. Steve George, the founder of EarthKind™, is passionate about this program and is a great team builder and leader. David Zlesak

Plants in cultivar trials are trialed using low maintenance principles and the knowledge gained from what has been learned through nutrition management studies (compost added initially and organic mulch maintained at a 3” layer), water saving practicies (watering during the establishment phase and then only in cases of extreme drought afterwards), no fertilizers (beyond the initial compost and maintained mulch layer), no deadheading or pruning, and no pesticides. In addition, it was confirmed early on that own-root roses (propagated from cuttings and not grafted) tend to be longer lived and more adaptable. Therefore, all EarthKind™ rose trials use only own-root roses and for winning EarthKind™ rose cultivars to be EarthKind™ they need to be sold as own-root plants as well.

Roses have become the model landscape shrub for EarthKind™ cultivar evaluation for some very good reasons. Roses are our national flower and have long been a favorite for many gardeners and landscapers due to their extended season of flowering, diversity of flower color, fragrance, form, plant size, and growth habits. In addition, with the great diversity among them in performance, cultivar trials are very useful to highlight the best performing roses for a typical landscape. By using the EarthKind™ approach, regionally adapted cultivars can be identified that demonstrate consistently superior performance well-suited to particular climates. Roses that are EarthKind™ for one region may or may not prove adapted enough to be EarthKind™ in another region. EarthKind™ winning cultivars can be endorsed with confidence to the general public, landscapers, nurseries, and municipalities. With some basic attention given to soil preparation, site selection, mulch, and irrigation during establishment, these roses are highly likely to succeed. This results in many positive benefits including:

  • Greater satisfaction and people more likely to continue gardening.

  • A greater positive impact on the environmental with less need of pesticides and over application of fertilizers to try to make poorly adapted plants succeed.

  • Greater financial savings for especially municipalities and others managing large landscapes due to more efficient use of limited financial and human resources.

  • An open door to provide those interested with more information about other components of EarthKind™ to support environmentally sound landscape stewardship.

Photo 4: There is great variation among rose cultivars for pest susceptibility and landscape performance as seen among these roses at the Minnesota Landscape Arboretum. David Zlesak

Status of EarthKind™ rose research before the Northern EarthKind™ Rose trials began

Scientists at Texas A&M University identified 17 rose cultivars that have earned EarthKind™ status for the South (two more have been added since for a total of 19). For a rose to become EarthKind™ it must: Perform well in an initial large, university trial making the first cut and then perform consistently well regionally across multiple sites hosted by Master Gardeners, parks, botanical gardens, interested individuals, and/or community gardens. The roses that are included in the large phase one university trials are very carefully chosen taking into account any previous trial data from within and outside the region and recommendations from horticultural leaders including nursery professionals and rose societies. The goal is to use the limited resources available for these trials very wisely. By clearly eliminating roses that do not possess the level of pest tolerance or general adaptability necessary to merit EarthKind™ from the start, there will be more resources to devote to those that are more likely to prove themselves as EarthKind™. Although antidotal evidence helps to focus in on roses to initially include in the trials, to earn the prestigious EarthKind™ status, roses need to have supporting data behind them from the full EarthKind™ trial protocol confidently supporting their inclusion among this very elite group of cultivars.

Photo 5: Many of the gorgeous EarthKind™ winning roses for the South, like ‘Mme. Antoine Mari’, are not hardy enough to reliably survive winters in our northern climate. David Zlesak

For the larger, initial university trial where a hundred or more cultivars are trialed, the duration of the trials is four years. Data is taken monthly during the second through fourth growing seasons with no data taken during year one to allow for plant establishment and any residual pesticides to dissipate. The monthly data is taken on traits assessing pest tolerance, flowering characteristics, and overall plant habit and landscape impact. The very best of these roses in the phase one university trial, along with a reference or standard cultivar for comparison, are then planted at several additional sites across the region. These roses are monitored for three years with data taken years two and three. After this point there is enough data to understand the cultivar’s performance throughout the region and designate winners with confidence. Those roses that are on the fence may be put in additional secondary trials until enough data on their overall performance is gathered to confidently decide if they have earned EarthKind™ recognition or not. Although this extended timeframe slows down the evaluation process in comparison to typical rose evaluation programs that typically grow roses only two years, it elevates the value of roses earning EarthKind™ designation. With variable climatic conditions over years, the extended trial period also helps to expose the plants to more environmental factors and allow them to mature and assess their long term landscape adaptability. The priority isn’t to have newly designated cultivars each season to fuel marketing efforts, but to have those that are designated as EarthKind™ to truly possess superior performance in a typical landscape in the region of designation.
Photo 6: ‘BUCbi’ (Carefree Beauty™) serves as the check or reference cultivar in EarthKind™ trials. It has proven to be EarthKind™ in the South and is reliably crown hardy here at the Minnesota Landscape Arboretum. David Zlesak

Besides the previously mentioned components of EarthKind™ trialing (number of years under evaluation; nutrition, water, and pest management components; regional adaptation; and monthly data collection that is generally a higher frequency of data collection during the growing season than other rose evaluation programs), the EarthKind™ rose program has a number of other features that set it apart from the leading rose evaluation programs. This includes attention to blocking, check or reference cultivars, and more of an independent consumer-based perspective and driving force. Although EarthKind™ works with nurseries to learn about new roses and obtain plants, nurseries are not a primary funding source for the work and all rose cultivars, no matter who bred them or when they were bred, can be included if they have the characteristics that suggest they have the potential to earn EarthKind™ status.

Blocking and check or reference cultivars are critical elements to cultivar trials of most crops and are employed in EarthKind™ trialing. Blocking (we use a randomized complete block design) involves separating out the replicates of a particular cultivar across the trial site. They are separated in different complete subsections of the garden with representatives of all the cultivars randomized when planted for more statistical power when analyzing the data. When, for instance, all four plants of a particular cultivar are planted by each other in a trial, like done in many of the leading rose trials, one does not know for sure to what extent the rose’s performance (good or bad) can be attributed to the cultivar itself or if the particular region of the garden they are all planted in is more or less suitable than another location. For instance, when all four plants of a cultivar with generally above average disease tolerance are planted next to a very susceptible cultivar, the true resistance of the above average cultivar may be difficult to see with all of the innoculum being spilled onto it from its neighbor. If blocking with randomization was used, the cultivar with above average resistance would be planted across the garden next to various other roses and the variation in disease incidence on the cultivar can be better documented and overall it should be possible to determine it has above average disease resistance. Having a reference or check cultivar common throughout all the trials is also important. The performance of this cultivar relative to the others can provide useful information for comparisons, especially when all trial cultivars for secondary EarthKind™ trials cannot be accommodated in a single garden.
Photo 7: The EarthKind™ Brigade includes several of the roses bred by the late Dr. Griffith Buck from Iowa State University such as ‘Winter Sunset’. Ron Shaw

Besides the continuing EarthKind™ rose trials going on in the South through the support of many partners including significant support from the Houston Rose Society, there is a collection of 30 rose cultivars, known as the EarthKind™ Brigade, that are being evaluated across the mid section of the United States. These 30 roses have enough cold tolerance to survive the winters in a large part of the nation, but most of these cultivars are not reliably winter hardy in USDA cold hardiness zones 3 and 4. There is a need to identify EarthKind™ worthy roses for zones 3 and 4 and the initiation of the Northern EarthKind™ Rose Trials.

Photo 8: The first Northern EarthKind™ Rose Trial was planted at UMore Park in Rosemount, Minnesota. Compost was incorporated within the four blocks and one of each of the 20 cultivars were planted in each block. David Zlesak

Initiation of the Northern EarthKind™ Rose Trials

Fortunately, there are disease-tolerant roses which will reliably survive our zones 3 and 4 winters without protection. Information gathered on the performance of such roses from nursery professionals, rose societies, and observations in our regional landscapes and public rose gardens formed the foundation with which we developed this first collection of 20 rose cultivars to trial. At this time, part of the criteria for cultivar consideration is that cultivars need to rebloom during the growing season and also rugosa roses are not being evaluated due to their susceptibility to iron chlorosis in higher pH soils. These criteria may be changed for future trials.

In addition, there is a modification to the pruning criteria and evaluation model compared to the South. Since most landscape roses encounter dieback in our climate, pruning will be allowed to remove winterkilled tissue in the spring. In addition, due to the growing reputation of EarthKind™ and wanting to provide information for northern gardeners, the trial will start with multiple sites across the north initially. This is also possible as there is a relatively small number of cultivars that have reputations of being reliably cold hardy and pest resistant for the north to begin with.

As of now there are 8 complete Northern EarthKind™ trial sites and one Northern EarthKind™ demonstration site at Muriel Sahlin Arboretum in Central Park in Roseville (a demonstration garden has one each of the cultivars planted with signage to promote the program and provide conformational data as to the performance of the different cultivars in the full sites). Three of these trial sites are in Minnesota (University of Minnesota Outreach, Research, and Education Park in Rosemount, zone 4; Centennial Park in Moorehead, zone 3; and The Sisters of St. Benedict in Crookston; zone 3), one in Iowa (The Horticulture Research Farm outside of Ames, border of zones 4 and 5), one in Nebraska (Haworth Park in Bellevue, border of zones 4 and 5), and Colorado (outside of Fort Collins, zone 3). The additional two are located in Kansas (John C. Pair Horticultural Center, Haysville, KS) and Texas (Texas A&M Commerce, Commerce, TX) to see how far south these roses perform well for possible inclusion in future EarthKind™ trials in those regions. Key collaborators for this effort and hosts of these sites include: Dr. Steve George, Dr. Derald Harp, Dr. Jason Griffin, Kathleen Cue, Anita and Mike Eckley, Joanne and Bob Langabee, Tamla Blunt, Randy Nelson, Nick Howell, Eric Castle, Mike Klawitter, and Patti Sullivan.

The twenty rose cultivars included in the current Northern EarthKind™ Rose Trials.


Horticultural class

Flower color

Approx. height in feet

Radbrite (Brite Eyes)

Large flowered climber

Pink Blend


RADramblin (Ramblin' Red)

Large flowered climber



John Cabot

Hybrid kordesii

Deep magenta


John Davis

Hybrid kordesii

Light Pink



Hybrid kordesii



William Baffin

Hybrid kordesii



Alexander Mackenzie


Light Red


BAIine (Yellow Submarine)




BAIlena (Lena)


Light Pink


BAIole (Ole)


Blush white


BAIore (Polar Joy)




BAIset (Sunrise Sunset)


Pink Blend


BAIsven (Sven)




Bucbi (Carefree Beauty)








George Vancouver


Light Red


Morden Blush


Blush white


Prairie Joy


Light pink






Summer Wind




a Trademark or exhibition name, if different from cultivar name, is listed in parenthesis.

Photo 9: The Northern EarthKind™ Trial planted outside of Ames, Iowa at the Horticulture Research Farm. David Zlesak
Photo 10: Some of the Northern EarthKind™ Rose Trial cultivars under evaluation include: A). ‘Frontenac’, B). ‘George Vancouver’, C). ‘BAIole’ (Ole), and D). ‘BAIset’ (Sunrise Sunset™). David Zlesak

Planting occurred in spring of 2007 for the UMore Park site and late 2007 or 2008 for the other sites. The first year of data was collected at UMore Park in 2008 and will begin at the other sites in 2009. By the end of 2011, the data for all of these sites should be complete with the first possible Northern EarthKind™ winners announced in 2012. All the sites, excect for the Colorado site, are located within public gardens or research facilities. All of the Minnesota sites are easily accessible to the public for viewing.

Complementary EarthKind™ Work and New EarthKind™ Trials on the Horizon
Photo 11: Several hundred individual boxes of rose leaves were needed to evaluate the dozens of cultivars for their susceptibility to the three races of the pathogen causing black spot. Jolyne Pomeroy, Brandi Miatke, Vance Whitaker, and David Zlesak are pictured after finishing a round of inoculations in the laboratory. David Zlesak

In addition to working with collaborators to initiate the Northern EarthKind™ Rose Trials, the University of Minnesota is serving a key role for the EarthKind™ team in surveying roses for their tolerance to multiple races of the fungus (Diplocarpon rosae) that causes black spot, a very problematic disease in roses. The roses currently being characterized are the ones that have won EarthKind™ in the South, the 30 roses in the EarthKind™ Brigade, the 20 in the Northern EarthKind™ Rose Trials, and some recent promising cultivars touted as having extreme blackspot resistance. Vance Whitaker studied isolates of the fungus for his Masters from collections made all over Eastern North America for his Masters with his advisor Dr. Stan Hokanson. These isolates fell into three different races or forms. These races are well preserved and available to use to challenge these roses to ascertain their resistance under laboratory conditions. These results will be compared to field resistance ratings for the predictability of this lab assay in characterizing the performance of these cultivars in the landscape. If it proves to be predictive, this relatively quick assay can prove to be very useful in objectively helping narrow down which cultivars merit inclusion in future trials. We may be able to determine a minimum threshold of resistance a cultivar needs to have in these assays to include in the trials and be able to hold up in the landscape to this very destructive disease and have the potential to earn EarthKind™. With the variability in this pathogen, being able to assess resistance to the different forms out there is a tremendous advantage. Variable reports for resistance of a cultivar often stem from which form(s) of blackspot happen to be present in a particular garden.
Photo 12: These leaves are of the same rose cultivar. This rose is highly resistant to one of the races (A.), but very susceptible to another (B.). This highlights the variability of performance possible across different gardens depending on which form of the pathogen is present. David Zlesak

The next set of Northern EarthKind™ trials are on the horizon. In order to best get an idea of the performance of some of the newer landscape roses in our climate under lower input conditions, over 20 such cultivars have been planted in preliminary trials at UMore Park, Lyndale Park Rose Garden (Minneapolis), Virginia Clemons Rose Garden (St. Cloud), and the Leif Erikson Rose Garden (Duluth). Observations on their general disease tolerance and winter hardiness will be very helpful in determining which merit inclusion in the next Northern EarthKind™ Rose Trial. In the near future there are plans to initiate regional EarthKind™ herbaceous perennial trials and shrub trials. Members of the EarthKind™ team met this past October to brainstorm how to get this work off the ground. Dr. Ann Marie Vanderzanten from Iowa State University will lead the national effort for EarthKind™ Perennials and our own Kathy Zuzek, University of Minnesota Extension Educator, will lead the national effort for EarthKind™ Shrubs.
Photo 13: Five plants each of 21 recent or new landscape roses were planted at UMore Park in spring of 2008 in order to learn of their pest tolerance and winter hardiness for possible inclusion in the next Northern EarthKind™ Trial. David Zlesak

Efforts are also underway to continue to expand EarthKind™ internationally (EarthKind™ work is currently underway in the United States, Canada, Bermuda, India, and New Zealand) and to initiate more work in turf and soil management. Part of the goal of international EarthKind™ rose research is to help people identify the most adapted roses for their regions and then eventually share and trial such roses across regions to see how widespread these roses are adapted. This will lead to a growing collection of the world’s most adapted landscape roses that will not only serve those that want to grow adapted roses in their region, but also breeders as they can use this information to narrow in on parents that will hopefully transmit superior characteristics to new roses. More information about EarthKind™ resources can be found at: and . In addition, a review article documenting the EarthKind™ rose research has been accepted and will be coming out in a special issue of the scientific journal Floriculture and Ornamental Biotechnology devoted to rose research slated for release in February 2009. ( Please look for periodic updates about EarthKind™ research in the Yard and Garden News and other publications.

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