ASK THE MASTER GARDENERS
Q: We have had very little rainfall this autumn. Do I need to water my landscape plants?
A: The New York metropolitan area recorded its third driest October on record this season. Brush fires flared up in parched areas. Landscapes that were not irrigated had soil so dry that it was nearly dust-like. We saw hydrangeas and other shrubs wilting to the point of being crisp; pachysandra lying withered and flat; deciduous trees with curling leaves and turf going into dormancy. All of this indicates that it is particularly critical to water plants as needed so that they don’t go into winter with a moisture deficit.
This is especially important for new transplants or installations, especially newly seeded or sodded lawns and newly planted broad-leaved evergreens and evergreen conifers. Otherwise they may be more susceptible to increased winter injury and establishment failure. If the soil is moist to a depth of 6 or more inches, additional water should not be necessary. If the soil is dry, and precipitation is not sufficient, aim to give them an inch of water weekly. If irrigation systems have been shut off for the winter, it may be necessary to hand water or use portable sprinklers.
We may have caught a break with deciduous trees and shrubs, as most leaves have fallen and are no longer functioning, so moisture loss (transpiration) has largely stopped. Therefore, if the trees were watered, their buds will probably make it through the winter without drying out (desiccating). But trees that have dried out severely since summer, especially on marginal sites, may be in trouble. Evergreens may suffer the most.
Remember, too, that even established trees and shrubs exposed to overly dry (or overly wet) conditions may not exhibit symptoms of injury until months or sometimes years after the offending events. This often leaves property owners mystified as to what caused the death or damage to their treasured landscape specimens. We may see the effects of that in the form of less disease resistance, branch die-back and root loss. This will show up over the next growing seasons, long after the drought has passed.
Gerald Giordano, Senior Horticulture Consultant/Cooperative Extension Agent, Cornell Cooperative Extension of Westchester