Deep, heavy clay soils generally hold more water and are slower to dry out, but if dry conditions persist, even these soils will not support plants well. Typical signs of drought or moisture stress appear as persistent wilted foliage that does not recover at night. If the conditions remain dry enough, small, terminal twigs on trees and shrubs will die and become brittle soon after a summer drop of leaves. Stored moisture in the plant will slow the death of twigs and branches to a point, but this stored moisture is the plant's reserve for the next growing season. If excess amounts of the stored moisture are used during the summer and fall season, the winter survival and the spring growth potential will be reduced.
Plants still lose moisture to the atmosphere in winter but at a slower rate than in summer.
If its reserves are reduced it is possible for a plant dry out to that critical point at which life ceases in the tissue and additional dead stems and branches appear next spring. Early fall leaf color is another sign of drought stress in plants like dwarf winged euonymus, maples, viburnums and some oaks. Rainfall and irrigation are about the two most important things that will help woody landscape plants at this time of year. Most plant roots are active until the soil temperature drop to about 40 degrees F. later this fall. Plants will take in available moisture and replenish what has been lost or used during the season.