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Wednesday, Sept. 19, 2007 12:38 pm

We need rain

Be sure to water plants now to avoid consequences later

Untitled Document The crisp, cool air has been a welcome relief from the 90-degree temperatures, but we have not been as blessed with rainfall. Last week I dug a hole for an addition to my garden. I had to wedge my body between the fence and the shovel to get enough leverage to break the surface of the soil. The usually rich, black loamy soil has turned to concrete. Digging an 8-inch-deep hole for my new peony was no easy feat. I couldn’t believe that there was no moisture to be found in this usually beautiful soil. We need rain! We could ask for a miracle and hope that it rains, but in the meantime get out and water your trees and shrubs. Entering winter without adequate soil and tissue moisture leaves trees and shrubs susceptible to low-temperature injury and damage resulting from rapid fluctuations between warm and cold.
Evergreens, including broadleaf evergreens, should also enter winter well watered. These plants continue to lose water through their leaves in the winter. Broadleaf evergreens, including boxwoods, yews, rhododendrons, and hollies, are especially susceptible to winter burn caused by frigid winds.
Besides watering, it is a good idea to add a 3-inch layer of mulch over the root zone to help conserve soil moisture. Mulch at least to the edge of the tree’s canopy. How much water? This question is difficult to answer. Some variables include the size of the plant and the soil type. Most trees and shrubs will benefit from 1 inch of water per week applied in a single slow, thorough soaking. A rule of thumb for a newly planted tree (less than two years old) is to slowly apply 1 gallon of water for each inch of trunk diameter every five to seven days. When watering mature trees and shrubs, be sure to cover the entire root zone of the plant. Keep in mind that the root zone of a mature tree can extend to three times the width of the tree canopy. How do you measure an inch of water? If you’re using a sprinkler system, set an empty can in the area where the water falls. When the can contains an inch of water, an inch of water has been applied to the ground. Because the ground in many areas is dry to at least 1 foot down, the initial watering could be more than 1 inch. Remember, tree and shrub roots will absorb water until the ground freezes. Trees under stress, including water stress, become more prone to insect and disease injury. Our extension office has received many calls recently about tree decline. Often such decline can be traced back to improper watering practices or the lack of moisture. My message for this month: Water, water, water! · The University of Illinois Extension Sangamon-Menard Unit will be offering a few programs in the coming week. Programs will be held at the extension’s office, on the Illinois State Fairgrounds: “Preserving Flowers and Seed Collecting” — The extension’s master gardeners will lead the free presentation at 5:30 p.m. Thursday, Sept. 20.
“Seasonal Care for the Home Landscape” — I will be leading this free program, which will offer seasonal tips for maintaining trees, shrubs, lawns, flower beds, and vegetable gardens, at 10 a.m. Tuesday, Sept. 25. “Indoor Plant and Household Pests” — Entomologist Phil Nixon will tell you how to identify and manage insect pests at 1 p.m. Tuesday, Sept. 25, and again at 7 p.m. Thursday, Sept. 27. To reserve a seat, call 217-782-4617. The cost is $2 per session.
Jennifer Fishburn is a horticulture educator with the University of Illinois Extension Sangamon Menard Unit. Contact her at 
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