Drought and heat are inevitable challenges in the vegetable garden. In the southeastern United States, rain can seem like a festival or a famine—there’s either too much or too little. Unpredictable rainfall combined with periods of extreme heat make summer the most stressful season (for plants and people) in the garden. Wet summers result in a variety of crop diseases and out-of-control weeds, while droughts result in stunted, wilted crops that produce little, if they survive at all.
Cory Tanner, director of the Clemson Extension Horticulture Program team, shared the following tips to help your vegetable garden thrive during the hot summer months:
• Most vegetable crops require the equivalent of 1 inch of rainfall per week to grow normally. This requirement increases when temperatures exceed 90 degrees Fahrenheit.
• Don’t wait for your plants to show stress. By the time they wilt, some damage and yield loss will have occurred. Avoid drought stress by watering your plants before the soil becomes extremely dry. Dry soil can sometimes be extremely difficult to rehydrate, depending on soil type and composition.
People also read…
• Use organic mulch (shredded leaves, straw, hardwood mulch, etc.) to reduce water evaporation from the soil and protect the soil and plant roots from extreme heat.
• Consider temporary shading to give plants relief during times of extreme heat. Most vegetable plants prefer full sun for best production, so shade should only be used temporarily during the hottest weather. Floating row covers suspended over a crop are a handy way to provide temporary shade in the garden. Container gardens can be temporarily moved to shady locations.
• Fruit plants, such as tomatoes, thrive best when provided with even soil moisture. Avoid large fluctuations between wet and dry soil by watering frequently and deeply during dry periods. This not only reduces drought stress, but also common problems in tomatoes such as blossom end rot and fruit cracking.
• Use drip irrigation, which applies water directly to the soil so it doesn’t become airborne and is kept off the foliage. Drip irrigation is 90-95 percent more efficient than sprinkler irrigation. It also applies water more slowly, allowing more of it to penetrate the soil and wet a deeper soil profile.
• Make sure you water deeply. Shallow watering can be more damaging than no watering at all. When watering, make sure the moisture reaches a soil depth of at least six to eight inches. Otherwise, plant roots will be concentrated near the soil surface, making them more susceptible to drought and heat stress. Deep watering encourages deeper rooting and more resilient plants. Check your system by periodically digging into the soil profile after a watering cycle to see how deeply the soil is wetted. If the water doesn’t reach the recommended depth, you may need to increase your watering time or the number of watering cycles you run, or both, depending on your soil type and irrigation system.