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February 2009 Archives

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!

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.

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.

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.

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.

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.

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.

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.

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.

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