Master Gardener: Putting the garden, yard to bed

By Molly Nemec—

Summer may be over, but there is still plenty of yard work to do.  Spending a crisp, sunny day in your yard is a worthy way to get exercise and vitamin D before the dark days of winter are upon us.

Photo supplied
Photo supplied

One chore that many people forego is watering newly-planted trees.  Trees need at least once inch of water per week until the ground freezes to increase winter survival rates.  Keep a rain gauge to record rain amounts.  When necessary, water young trees liberally every 7-10 days.  Saturate the soil with a slow-running hose near the “drip line,” the area under the branches, to soak the entire root zone.  Don’t be tempted to water lightly and frequently in autumn or summer.  This can be detrimental to the root system and can cause the roots to remain near the tree.  Roots that do not grow out will not anchor the tree as well and the tree may tip or be uprooted by strong winds.  Proper fall watering can help prevent browning and desiccation injury of evergreen trees, as well.  Sun and cold wind cause pine, spruce, arborvitae and yews to transpire and lose water through the needles.  They’re unable to replenish as the roots are frozen.  Late-season watering and mulching can help prevent some stress on the tree.

Young and thin-barked trees (maple, honey locust, linden, plum, apple, mountain ash and crabapple) are susceptible to sunscald.  This occurs in late winter when the sun gets stronger, thus stimulating the cambial tissue to become active.  When the temperatures dip at night, the active tissue is damaged.  This can result in a splitting wound or “canker,” that can decay, lead to a weak trunk and leave the tree vulnerable to disease.  Depending on the severity, this can kill a tree.  Lightly-colored plastic tree guards reflect the sun and keep trunk temperatures more constant.  Cover trees in November and remove in early spring before moisture causes fungal damage.  Young trees can be covered for at least two winters; thin-barked trees can be covered for at least five winters.

Mulching trees with three to four inches of wood chips or shredded bark will prevent soil temperatures from fluctuating and keep moisture in soil. Mulch should stay away from base of the tree for necessary air circulation.  If mulch touches the tree, it can cause rotting and fungal problems.  In essence, don’t create a “mulch volcano” — instead, think “mulch donut.”

Fall bulbs should be planted as soon as possible to encourage the development of strong roots before soil is frozen.  Tulips, daffodils and other bulbs need to be watered if rainfall is sparse.  Add several inches of mulch to help insulate bulbs and to keep them safely dormant during any late winter warm ups.

 — Article by Molly Nemec, Chisago County Master Gardener

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