Tomatoes, peppers, melons, squash, pumpkins, cucumbers and beans often drop their blossoms without setting fruit when temperatures rise above 90°F. There’s not much you can do but wait for cooler temperatures to arrive. As more favorable conditions return, the plants will resume normal fruit set.
Cool-season crops, such as lettuce and spinach will bolt, or produce seed stalks, causing the flavor of the leaves to become bitter. It’s best to remove these crops and replant with heat tolerant vegetables such as beans, carrots or chard.
Extremes in temperature and soil moisture often bring on blossom-end rot, a fruit disorder caused by interruptions in watering. It commonly affects tomato, pepper, cucumber and squash causing them to develop a round leathery brown or black patch at the bottom of the fruit. Inside, the tissue is hard and brown. The rot occurs when there is a lack of calcium supplied to the developing fruit. More than enough calcium may be present in the soil. The problem develops, however, when changes in soil moisture or sudden water shortages disrupt the flow of calcium from soil to developing fruit. Therefore, to avoid blossom end rot, the soil must be kept evenly moist. Irrigating during dry periods and mulching to conserve soil moisture will help minimize this problem.
Container plants out on the patio, including hanging baskets will really be stressed by the heat wave, since they have much less buffering of temperature extremes on the root system. In addition to watering more frequently in hot weather, providing afternoon shade will help reduce heat stress.
The good news is that weather is always changing. These thermal blasts don’t occur that often here in our coastal climate. The extreme heat won’t last forever — it will just seem like it. In the meantime, try not to overdo the garden work. Aim to complete your chores very early in the morning or in the evening when the sun is less intense, take frequent breaks and drink plenty of water to keep yourself from wilting.
Some of our plants look totally fried from last week’s intense heat. Will they survive or should we go ahead and remove them?
Intense heat can produce a variety of symptoms in addition to scorched leaves. Depending on the plant variety, intense heat may also result in yellowing of leaves, wilting and even leaf drop. The extent of damage will depend on a number of factors including the amount of water present in the plant leaves and roots, shading available to the plant, whether the plant was over-fertilized with nitrogen, the general health of the plant, and reflected light and heat from surrounding surfaces like walls and pavement.
Even though some plants may look totally scorched and appear to be dead, in many cases they will survive. Scorched leaves eventually will be replaced with new growth next spring. Other plants, like perennials, will continue to produce new foliage this growing season.
The most important thing for now is to provide adequate water to speed the recovery process. Make sure that sufficient water is applied to thoroughly wet the entire root zone. A good method for doing this is to use soaker hoses. For prized plants and larger specimen shrubs, place the hose on the root mass and letting the water trickle for several hours will also do a good job of soaking the root zone.
On a final note, remember that frequent, shallow sprinklings do little to alleviate drought conditions.
Editor’s Note: This article first appeared on www.hometowndebate.com 6/27/12. If you would like to respond to this story, go to hometowndebate.com