Preventing heat stress in plants

Keep trees healthy with lots of water. (photo by Makio Kusahara)

As we face another weather forecast full of hot temperatures, gardens around Baltimore are suffering from heat stress. Leaves on some plants may be curling up and turning brown. Some plants do not flower or set fruit. Plants can recover from heat stress if properly cared for, but they may not be as productive as usual. Take time to protect your vegetables, flowers, shrubs, trees and lawn from heat stress before it is too late.
Frequent watering is the most important way gardeners can ward off heat stress. Lawns and many plants need at least one inch of water per week. Using a sprinkler is more efficient than hand watering. Because of our mighty snowstorms last winter, Baltimore’ reservoirs have plenty of water this summer. But, if water restrictions go into effect in the future try to reuse dishwater or other waster water on your favorite plants.
Vegetables and flowers may go dormant during a heat wave. Blossoms may fall off of vegetable plants and flowers may not bloom at all. Since many vegetables need about 2 inches of water per week, double that to four during times of high heat. Water these plants in the evening so it can soak in during the time when the sun is gone.
Give special attention to shrubs and trees that are less than 2 years old. They need about 1 and ½ inches of water per week. But, if it is very hot, like our recent days of near 100-degree temperatures, they need at least 2 to 2 ½ inches per week. Plants, even grass, will compete with the trees or shrubs for moisture so it is best to have a coating of about 3 inches of mulch around the base of the tree. Make the circle of mulch as wide as the tree’s canopy.
Lawns will go dormant and look brittle and brown. Like trees, they also need beyond their usual 1-inch of water per week and the amount should be doubled. Water the grass in the evening or early morning to prevent disease.