Summer can be the most stressful time of year for landscape plants, with heat and drought being the main offenders. When not receiving sufficient moisture, plants are much more susceptible to insect and disease damage. Trees are the most valuable landscape plants and can be the most difficult to replace, so it is sensible that they should be given priority during periods of drought.
Lack of water is not a clear indication of a drought when it comes to trees. Many trees have deep, active roots that can easily survive short periods without rain or moisture, but it is crucial to notice when they are becoming drought-stressed. Wilting and curling leaves will appear on drought-stressed deciduous trees. Leaf edges will eventually turn brown and crispy and may drop prematurely. Evergreen needles will begin to turn brown at the tips. As the drought continues, the entire needle will turn brown.
Generally, the trees most at risk are those that are newly planted or transplanted, as well as any younger trees. The root system of these plants is underdeveloped or likely damaged by the planting. Trees that are growing in a restricted area should also be of great concern. This includes trees planted in containers and trees in the narrow grass strip between the street and sidewalk. Trees that are grown adjacent to your house or driveway, where they suffer more from reflected heat and have less underground space to spread their roots to collect sufficient moisture, are also at risk. Drought-sensitive plants like birches, beeches, dogwoods, Japanese maples, and magnolias should also be given priority during drought conditions.
It is best to begin good watering practices before the tree succumbs to drought stress. Trees need approximately one inch of water per week. If Mother Nature is not supplying it, then you should.
It is best for the tree if the required water is applied all at one time to the soil, slowly and deeply. You can accomplish this by using irrigation bags on newly planted or small trees. Trees in a restricted area are best watered with a slow dripping hose placed at the base of the tree and frequently moved for even distribution. For more giant trees, a soaker hose laid in a spiral pattern, radiating from the tree trunk out to the drip line, works well.
Take care that if your community has watering restrictions during drought conditions, you follow approved practices to maintain your trees without risking fines or fees from illegal watering.
You can help your trees resist drought conditions with a little thoughtful care, and they will continue to thrive, helping to provide shade and beauty in your landscape.