This year has been a little out of the ordinary, regarding weather. It was quite chilly for what seemed like a long time this spring. Then, when it did warm up a little, we kept having very cold overnight lows, some quite damaging to the plants that were growing. As I assumed, the summer would come on with a vengeance, which it did. Suddenly, it got very hot, windy, humid, and dry. This can be damaging to our plants for multiple reasons.
We need to make sure that we are watering all our plants in this heat. Even trees need a drink sometimes. The best way to water a tree is to let a hose trickle at the base of the tree or use a small sprinkler for up to an hour, depending on the size of the tree. Younger trees would only need to be watered for about 20-30 minutes. This should be done once a week with younger trees if we are not seeing natural precipitation.
Grasses may also be dealing with some heat stress. Visual cues can be used to determine water stress on lawns. On drought stressed lawns, you will notice that the wilted grass will turn blue-gray or grayish-green in color. You may also see that your footprints will remain visible in the lawn after walking on it. Turf with these signs should be watered that evening or the next morning. The best time to water a lawn is early in the morning, between 4am-10am. Even with automatic irrigation systems, the best way to water a lawn is to just turn it on when irrigation is necessary, not to set it and forget it. If running a pre-set irrigation system, 1-1.5 inches of water per week is adequate for home lawns. This can be applied over 3 applications per week at about ½ inch per watering.
We also need to remember to keep watering our gardens as well. Gardens should also receive about one to one and a half inches of water per week. If possible, irrigation should be provided through soaker hoses or drip irrigation, to avoid wetting foliage, sprinklers can be used as well. If you water with sprinklers, it can cause diseases problems due to wet leaves, especially in the cooler temperatures of night, so just be sure to water earlier in the day to allow dry time.
Herbicide injury to many plants has started showing up. Herbicide drift can be done via the wind as well as through volatilization, which is when herbicides turn into a gas that moves to non-target plants. Volatilization occurs in warm, humid environments, or typically when temperatures are over 85 degrees and is common with 2,4-D and Dicamba products. Discontinue use of these products during the summer.
The signs of herbicide damage on plants include curling, cupping, and vein distortion of leaves. Certain plants are more susceptible to drift including tomatoes, redbuds, grapes, and oaks. If you do get herbicide damage to your tree or shrub, you cannot fix the damage that is already done, but most trees and shrubs will grow out of it. It is not advised to eat fruits or vegetables from plants that were hit by herbicide drift, due to the variables regarding the herbicide, there is no way to know when or if they will be safe for consumption.
Wilting is occurring lately on many of our plants as well. It was difficult on our plants to move quickly from a cool spring to very hot, windy conditions this summer. When you notice wilting on your plants, water them as stated previously. When plants are wilting due to heat or drought stress, they will often look much better or completely recovered in the mornings and be wilted later in the day.