The heat wave last month left damage to unshaded plants in its wake. While ample watering in the morning — and in the case of potted plants repeated in the evening — normally suffices, plants that are not adjusted well to the extreme heat may suffer tissue damage and turn brown.
However, some of those brownish plants may not be dead. Rhododendrons and hydrangeas — even the sad-looking ones — can still bounce back.
What to Do
Those that are not too far gone may recover with extra care.
Plenty of water daily and some shading during the next heat wave will help. Dead blooms can be removed, but leaves — especially large ones — that are completely dry and brown may provide much needed shade for the green foliage below. Partially green leaves should be left on a plant, as the heat-stressed plant needs all the photosynthesizing surfaces it can get.
Pruning of any live part of the plant stimulates the time for a new growth, which may be compromised during the next heat wave. In addition, pruning wounds left on the heat-stressed plants may become an access point for pests to enter. Thus, pruning during the hot time of the year is not recommended.
Additionally, pruning spring-blooming shrubs in the late summer will deprive the plant of the buds for the upcoming spring. Stressed plants are more susceptible to all diseases; among them are bacterial and fungal infections of the root system, common due to overwatering.
Early morning watering facilitates the plant’s best water management.
Watering is needed if the top two inches of the soil are dry. After watering, the top six inches of the soil should be moist.
While the most efficient way of watering is via a soaker hose, watering by hand will suffice if the soil around the plant is watered with the spout close to the ground. Avoid wetting the leaves in full sun, as this may cause burns.
Rewatering plants in pots — especially those in hanging baskets — is a must on hot days. Evening watering should happen when the plant is shaded.
Mulching helps the soil retain water. Additionally, a shading cloth hung at least a foot above the plant may be necessary for delicate plants during a heat wave.