Homeowners will simply need to wait and see if severely stressed trees will live through the winter. Though humans could escape into air-conditioned homes, plants were at the mercy of the weather conditions and our gardening practices. But, even the tough black-eyed Susans showed signs of heat stress, their deep green leaves drooping long before day's end. Foliage will lose water as a method to keep cool. Wilting leaves are a sign that the plant has lost more water than is being replaced by the roots.
Plants sacrifice old growth in favor of new growth during stressful weather conditions.
Thus, extreme water loss causes drying and browning of leaf tips and along the edges of older leaves. At best, incorrect watering will be of no benefit whatsoever to plants. Lawns planted with the cool-season grasses, such as fescue and bluegrass, have been especially hard pressed to stay green, even with watering. This may be partly due to the fact that the cool-season grasses don't benefit from water during the hottest times of the day since they simply are not well adapted to hot temperatures. If stomates are shut, the plant doesn't use water in or applied to the soil.