When the weather suddenly skyrockets with temperatures above 85 F. (29 C.), many plants will inevitably suffer from ill effects. However, with adequate care of outdoor plants in extreme heat, the effects of heat stress on plants, including vegetables, can be minimized.
How Plants Cope with Heat
So how do plants cope with heat once temperatures begin to soar? While some plants, like succulents, are well equipped with handling heat by conserving water in their fleshy leaves, the majority of plants do not have this luxury. Therefore, they will normally suffer from the in heat some way or other.
Generally, heat stress of a plant will show itself by wilting, which is a sure sign that water loss has taken place. If this is ignored, the condition will worsen, as the plants will eventually dry up, turning a crunchy brown before dying. In some cases, yellowing of the leaves may occur.
Heat stress of a plant can also be recognized by leaf drop, especially in trees. Many plants will actually shed some of their foliage in an attempt to conserve water. In excessively hot weather, many vegetable crops have difficulty producing. Plants like tomatoes, squash, peppers, melons, cucumbers, pumpkins, and beans will usually drop their blossoms in high temps, while cool-season crops, like broccoli, will bolt. Blossom end rot is also common during hot weather and most prevalent in tomatoes, peppers, and squash.
The care of plants and flowers in hot weather is pretty much the same with exception to container plants, or those that have been newly planted. Of course, additional watering is a given, with new and potted plants requiring even more irrigation. In addition to watering more often, mulching plants can help conserve moisture and keep plants cooler. The use of shade covers, especially on vegetable crops, may be helpful as well.
Container plants will require daily watering, even twice a day in high temperatures. These plants should be given a thorough soaking until water can be seen coming out from the drainage holes. Placing water granules in pots also helps. As these will gradually soak up excess water, in times of dryness, the granules will slowly release some of this water back into the soil. Moving potted plants to a shadier location during the heat of the day is also recommended.