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 therefore should be given priority during periods of drought.
Identify
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.
Prioritize
Generally, the trees most at risk are those that are newly planted or transplanted. The root system of these plants is underdeveloped or has been damaged. Trees that are growing in a restricted area should also be of greater concern. This will include trees planted in containers, the grass strip between the street and sidewalk and trees grown adjacent to your house or driveway. Drought-sensitive plants like birches, beeches, dogwoods, Japanese maples and magnolias should also be given priority during drought conditions.
Water
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.
Methods
It is best for the tree if the required water is applied all at one time to the soil, slowly and deeply. This can be accomplished 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 moved frequently for even distribution. For larger trees, a soaker hose laid in a spiral pattern, radiating from the tree trunk out to the drip line, works well.
Tips
- Always water the soil and not the leaves or needles of the tree.
- 2 – 4 inches of mulch placed over the soil, under the tree, from the trunk to just beyond the drip line, will help to conserve soil moisture. Be certain not to mound mulch against the tree trunk.
- Water on overcast days, early in the morning or in the evening. Evaporation is slower during these times.
- Fertilizer can injure tree roots during times of limited soil moisture. Avoid using fertilizer during drought conditions