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Showing posts from June, 2011

Unusual Rudbeckia for your Garden

Robin Trott
Photo 1: 'Cherokee Sunset' rudbeckia.

Robin Trott, UMN Extension Educator

In a few weeks our ditches and roadsides will be full of those yellow daisies known as Black-eyed Susans or rudbeckia. A native wildflower and perennial favorite, rudbeckias are reliable plants that fill our gardens with brightly colored flowers from July through the first frost. They are easy to grow, adapt to a wide variety of soil conditions, have very few insect or disease problems, and bloom the first year when started from seed. However, they weren't always a staple of American gardens.

In the early 17th century, British plant collector, John Tradescant, collected roots from French settlers in the "New World". The plant was shared with other botanists and herbalists, and was soon popular in English Gardens. By the mid-1800's, it found its way into American gardens and was noted by an early garden writer as "the darling of the ladies who are partial to yellow."…

Watch For Earwigs in Your Garden

Jeff Hahn
Immature earwigs on milkweed.

Jeffrey Hahn, Asst. Extension Entomologist

Immature earwigs were have been seen in gardens recently and will soon turn into adults. Many areas of Minnesota experienced high earwig numbers last year. Be on the watch for them in your garden this summer. Earwigs are about 5/8 inch long, with a flat, reddish brown body and very short wings. They look like a cockroach or a rove beetle but are distinctive because of the pair of pinchers (cerci) on the tip of their abdomen. Nymphs are similar to adults except they are smaller and generally lighter in color.

Earwigs are most active at night and like to hide during the day in dark, tight, damp areas, like under potted plants, cracks between bricks and pavers, and on plants in buds and folded leaves. Earwigs are scavengers, feeding on damaged and decaying plant matter as well as weakened or dead insects and other small organisms. Earwigs can also feed on healthy plant material. This is when they …

Calendar: July 1, 2011

Julie Weisenhorn
Beautifully blooming petunias in the Display and Trial Garden on the St. Paul campus of the U of M.


Early maturing vegetables such as leaf lettuce, radishes and spinach turn bitter and go to seed in July's heat. Pull them up, add a little fertilizer, and replant with broccoli, cabbage or cauliflower to harvest next fall. Or, instead of vegetables, you could sow a "green manure" cover crop -- clover, buckwheat, or annual rye-- to keep weeds out. Then turn them into the soil in the fall, before they go to seed, to add nutrients and organic matter for next year.

Make a habit of deadheading (removing faded blossoms) whenever possible from flowering annuals and perennials to prevent infection by the gray mold pathogen, Botrutis. (this disease is favored in warm, humid weather typical of July and August.) Flower infections can ultimately lead to the death of the entire plant. Of course, deadheading keeps plants looking better, too, and encourages them to keep…

Preventing and Reducing Tomato Leaf Blights with Cultural Controls

Michelle Grabowski, University of Minnesota Extension Educator



M.Grabowski, UMN Extension



Gardeners that grow tomatoes in Minnesota are often quite familiar with fungal leaf blights. High humidity, frequent rains and heavy dew can all favor fungal leaf blight. All three environmental conditions are common in Minnesota and it is difficult to grow tomatoes without encountering fungal leaf blights.

There are two very common fungal diseases of tomato that occur in Minnesota; Septoria leaf spot, caused by Septoria lycopersici, and early blight, caused by Alternaria solani. These two fungi thrive in very similar conditions, and it is not uncommon for tomatoes to have both diseases at the same time. Both fungi can come into the garden on contaminated transplants or seeds. They then survive in leaf debris from year to year. Rain and irrigation splash fungal spores up onto new leaves from the soil and plant debris below. New leaf spots soon produce spores. These spores are then splashed onto high…

All Hail to the (Ant) Queen

Jeffrey Hahn, Asst. Extension Entomologist



Jeff Hahn
Photo 1: Pavement ant queens (note two-segmented petiole between thorax and abdomen).

There have been questions lately about winged ants being found in and around homes and other buildings. Nearly all ant species in Minnesota (Pharaoh ants are an exception to this) produce mating swarms, i.e. winged males and females, at certain times of the year. These reproductives emerge and fly out of the nest, typically in large numbers. The males die shortly after mating with queens. The queens fly off in search for a suitable place to start a nest, although the vast majority do not survive long, being eaten or succumbing to the elements.

Upon landing, the queen breaks off their wings. As she starts construction of the nest, she lays a batch of eggs which she cares for until they mature into adults. From that point on, the workers assume all of the work responsibilities and the queen's sole job is to lay eggs. She is taken care of …

Unusual Bouquet Fillers for your Cutting Garden

Robin Trott
Photo 1: Limonium sinuatum. Minnesota gardeners struggle to balance a short growing season with a diverse garden. Many beautiful floral varieties just don't work in our Zone 4 (with pockets of zone 3) environment. This means that we have to rely heavily on annuals for our cut flower gardens. Zinnias and sunflowers provide bright color; annual rudbeckia, helichrysum and snapdragons make wonderful focal flowers in any bouquet; but what to grow for interesting filler? Baby's breath is an option, but is overused, and readily available at your local florist. I tend to look for something unique, fragrant and maybe a little quirky to give my arrangements that unexpected touch that sets them apart from other bouquets. I grow herbs, grasses and smaller flowers to complete my floral arrangements.

Limonium sinuatum (statice) has paper-like bracts that later bloom with delicate white flowers. Once Statice starts blooming it continues to bloom until frost. When harvesti…

I never met a beard I didn't like - on an iris, that is!

Karl Foord, UMN Extension Educator

I took a closer look at bearded irises this past week and two things intrigued me.
The first thing that intrigued me was the amazing variation in iris petal and beard colors (photos 1-4). It was also interesting to observe the change in beard colors throughout their length as they moved from the exterior part of the petal to the interior part of the flower (photos 5-7).

The second was a question of how did this flower actually work given the very obvious and showy petals and the less obvious male stamens and female pistils. The iris flower has a unique structure whose purpose is to avoid having pollen from this flower's male stamens transferred to the same flower's female stigmatic surface and pistil. As the bee enters the flower tracking along the beard it passes a flap that the insect will push past and fold back exposing the moist receiving part of the stigmatic surface capturing pollen on the hairy back of the insect. As the bee continue…

Calendar: June 15, 2011

Conserve moisture by watering early in the day, when temperatures are lowest and winds have not picked up yet. Try to water at the base of the garden and landscape plants. Use soaker hoses and sprinklers that don't shoot way up in the air; too much water will be lost to evaporation. Avoid watering at night if possible, as foliage that remains wet overnight is more prone to a number of plant diseases. Do water at night, though, if that's your only option.



Yard and Garden News Editor: Karl Foord
Technical Editor: Bridget Barton


Tent Caterpillars

Jeffrey Hahn, Asst. Extension Entomologist


Michelle Grabowski
Small eastern tent caterpillar tent.

There are two common species of tent caterpillars that are now active in Minnesota, eastern tent caterpillars and forest tent caterpillars. Both normally hatch closer to early May, but the cool spring weather we have experienced has slowed down their emergence and they only first started to appear closer to the middle of the month. Here is how you can distinguish between these insects.

Eastern Tent Caterpillars
This insect is easy to identify because it constructs silken webs in the fork of branches as soon as they young larvae hatch. The caterpillars feed outside of the tents on leaves during the day (as long as the weather is nice) and return to the webbing at the end of the day and during rainy weather for protection.

The caterpillars are bluish black with yellow and a white stripe running the length of the top of its body. They are also mostly smooth except for a series of hairs s…

Early June Home Lawn Care Tips

Bob Mugaas, UMN Extension Educator


Photo 1: Newly emerging crabgrass seedlings. Bob Mugaas.
1. In many areas of the state, crabgrass, along with other warm season annual grasses are or will soon be germinating in lawns. See Picture 1. Once crabgrass has emerged from the ground, control strategies need to be changed. Herbicides directed at controlling crabgrass above ground are known as postemergence products. Be sure to select those products that are specific to visible, actively growing crabgrass plants only. Those products labeled as grass killers are usually designed to kill all kinds of grasses, including lawn grasses, not just crabgrass. Products sold as broadleaf weed and grass killers may or may not be safe for use on lawns. Be sure to read the product label carefully as to whether or not it is a product that is safe for use on lawn grasses. When treating crabgrass after it has emerged from the ground, be sure that the desirable lawn grasses are not under any kind of he…

Growing Sunflowers for your Cutting Garden

Robin Trott, UMN Extension Educator

Cherry Rose. Robin Trott.
The Sunflower, or Helianthus, is a very popular flower to include in an annual cutting garden. A native of North America, the sunflower comes in a variety of sizes, growing habits and colors, making it an ideal choice for the home gardener. From the Giant sunflowers like "Kong", to the multi branching "Italian White" to the petite "Teddy Bear", an 18" tall puff-ball; there is a sunflower to match every gardener's taste and purpose. One of my favorites from last year was a pollen-less variety called "Cherry Rose". This 6' tall, branching plant is covered with 5" lemon yellow blossoms with red overtones. Grown in full sun, the lemon color abounds, in a more shaded site; the dark plum color is dominant. Another excellent choice, "Ring of Fire", is a mid-height plant (4-5') with 5" blooms. This late bloomer boasts bi-colored petals with a dark red b…

Iris Show

Photo 1: Iris cristata Crested Dwarf Iris. Karl Foord.

Don't miss the Iris show that is coming into its own at this moment. The Iris genus contains some 260 species of plants with showy flowers. The most commonly found garden iris is the bearded German Iris (Iris germanica), and its many cultivars (Photo 1). Other beardless iris types found in the garden are the Siberian Iris (I. sibirica) and the Japanese Iris (I. ensata), and their respective hybrids. The Siberian Iris can be distinguished from the Japanese Iris as the latter's flower is a more upward facing flatter flower. A number of other species are worth considering including the Dwarf Crested Iris (I. cristata) (Photo 2).

We have two excellent publications on Iris as follows:
"Iris" by Rhonda Fleming Hayes and David C. Zlesak and
"Gardens" by Deborah L. Brown.


Photo 2: The beard of a bearded iris, Iris germanica. Karl Foord.