Though drought in summer is more the norm, lack of rain this fall has resulted in late-season wilting of landscape plants. Such drought-stressed plants will be in poor condition to face winter, unless gardeners take action.
Though trees, shrubs and hardy perennials will be dormant in the winter, they continue to lose moisture through the biological process known as transpiration. Once the ground freezes, plant roots will no longer be able to take up water from the surrounding soil to replace this loss. The condition is further aggravated by strong winter winds.
Another important consideration is that next year’s growth and spring flowers will be determined by buds that will form this fall. So, even if your plants aren’t showing any symptoms now, the damage may become apparent in spring.
Gardeners can minimize injury by making sure plants are as hydrated as possible before the onslaught of winter. The best way to apply the water is by gently but thoroughly soaking the soil with 1 to 1.5 inches of water about every 10–14 days. This deep watering will encourage deeper root growth, which, in turn, will be better able to withstand periods of low moisture. Avoid frequent, shallow watering, which encourages roots to stay shallow and, thus, be more likely to succumb to drought. Sandy soil and containerized plants will need more frequent irrigation.
Watering of landscape and fruit plants should be aimed at where the roots naturally occur. While these woody plants do have some roots that grow deeper, most of the feeder roots, which are responsible for water uptake, occur in the top 18 inches of soil. Most of these feeder roots are concentrated below the dripline of the plant and beyond, not up close to the trunk. Allow water to thoroughly soak the target area by applying water at a slow enough rate to allow penetration, rather than wasting water by runoff. Don’t apply the water any faster than 1 inch per hour. As with annual plants, applying mulch will help conserve soil moisture.
It may not be practical to water the entire landscape, so you may need to practice a bit of triage first for the most vulnerable specimens, such as young plants and broadleaved evergreens, whether new or established. And there’s still hope that Mother Nature will come through with some rainfall for the rest of the landscape.