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Showing posts from December, 2009

Cool Plants for the Holidays

Carl Hoffman, University of Minnesota Extension Horticulturist

Be it reasons relating to the economy, an elevated environmental consciousness, or merely a reason to wear a new Snuggie™, we are lowering the temperature in our homes. We can easily compensate for the cool temperatures, but what about our plants?

As we enter the holiday season, many of us plant lovers like to use blooming plants to brighten and add seasonal cheer to the interior of our homes. Nearly all of the holiday favorites will perform well for a while, but then will begin to languish.

We are fortunate, however, that there are some blooming holiday plants that actually thrive in cool, or even cold, temperatures. Generally, temperatures above freezing, but below 50° F are considered cold, and temperatures between 50° F and 65° F are considered cool. Even some plants, like the poinsettia that prefer warmer temperatures will do quite well in a cooler environment if they are kept from cold drafts and are not overwatered…

Falling Leaves Reveal Unsightly and Mysterious Galls

Michelle Grabowski, University of Minnesota Extension Educator


As leaves are lost this fall, some gardeners are noticing unsightly lumps and bumps on the bare branches of their trees. A variety of causes, both living and non living, can result in irregular tree growth. However if round rough balls of wood are clustered on the trunk, branches, and twigs of the tree this is likely phomopsis gall. Phomopsis gall is a fungal disease caused by several species of Phomopsis. In Minnesota, Phomopsis galls are most commonly seen on Hickory (Carya spp.) and Maple (Acer spp.) trees. This disease can also infect American elm (Ulmus americana), several species of oak (Quercus spp.), Viburnum spp., Forsythia sp., rhododendrons and azaleas (Rhododendron spp.).
Phomopsis galls are spherical wood balls growing on tree trunks or branches. Galls may be as small as a pea or up to 10 inches in diameter. In most trees, the galls look like a cluster of small nodules or bumps, all pushed together into one l…

An Un-Ordinary Growing Season for All-American Selections at the MN Landscape Arboretum

Redistributed with permission from Arboretum News, Dec./Jan. issue
Ted Pew, Landscape Gardener, University of Minnesota Landscape Arboretum


The All-America Selections gardens this year at the Minnesota Landscape Arboretum were a mix of strange and stranger. For starters was the weather. Snowfall last year was low with minimal moisture content. The growing season--the end of May to the end of July--was cooler than normal. August was a bucket load of moisture but summer came in September with 80 degree temperatures and dry conditions. The 2010 AAS winners featured flowers only. The strange factor about the AAS was the expected colors on certain annuals. We had three outstanding cultivars for the 2010 sneak peek despite four plant diseases in the AAS bed and a crop failure.

Twinney Peach Snapdragon, aptly named for its color, had a double flower form with soft shades of peach, yellow and light orange color tones. This cultivar was quite floriferous--blooming early and up to frost--with a …

Cottony Grass Scale: A Year Later

Bob Mugaas, University of Minnesota Extension Educator

Jeffrey Hahn, Asst. Extension Entomologist



This past year saw a significant increase in the number of reported cases of cottony grass scale (CGS), Eriopeltis festucae, in Minnesota lawns. In 2007, we were only aware of one reported case of cottony grass scale. By 2008, that number had grown to about 6 newly reported cases with the one from 2007 disappearing entirely as there were no signs of infestation in 2008. However, by the end of September in 2009 the number of reported cases that we knew about rose sharply to between 75 and 100. While these were reported cases and not necessarily confirmed infestations, most recognized and described the symptoms, and ultimately the insect, as that shown in our previous article first describing this insect in Minnesota. (See the December 2008 YnG newsletter). Hence, it appears reasonable to assume that most identifications were likely correct.
In order to get a better feel for the scope …

December 2009 Garden Calendar

Karen Jeannette, Yard and Garden News Editor
Including excerpts from the 2009 Minnesota Gardening Calendar


It's not too late to protect your plants from Minnesota winter sunscald, animals, salt, snow, ice, and winter discoloration.  See: Protecting Trees and Shrubs Against Winter Damage
Mulch when the ground is frozen to keep the ground frozen, by applying a 4 - 6 inch layer of mulch (i.e. clean straw or leaves) over perennials or at the base of trees and shrubs.  Mulching to keep the ground frozen will help prevent those soil freeze-thaw cycles that can cause damage to roots and heaving of new plantings and perennials above the soil line.

Need to review which trees to select for Christmas?  See Kathy Zuzek's December 2008 article: It's Time for the Christmas Tree

Is your yard or garden ho-hum this time of year? Get inspired with Plants for Winter Interest  or visit your favorite full-size evergreens at the Minnesota Landscape Arboretum's arborvitae, pine, spruce, and