Gardening Through a Heat Wave
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The dog days of summer are hard on plants as well as humans. When temperatures rise, we don’t want to be outside digging in the dirt, and the heat can stress plants out just as much as us. Here are some tips on how to garden through a heat wave.
Watering Practices
You should check your soil moisture daily. If soil is dry at a finger's depth or more, it's time to water. Watering in the morning is a good practice because less water is lost to evaporation in the cooler part of the day, and it allows plants to fully hydrate before the heat of the day sets in. High temperatures mean a high potential for water to evaporate before it ever reaches the roots, so take time to ensure that plants are efficiently watered. Avoid sprinklers and instead use spot watering at the base of the plant, soaker hoses, or drip irrigation systems to provide water efficiently.
Watering Equipment and Systems
Plants in containers and hanging baskets may need to be watered twice a day. Especially when it is hot and windy, containers dry out very quickly. Be sure to check often.
Pay close attention to recently planted plants. Perennials, trees, and shrubs planted within the past year have not yet rooted fully. Most of the roots are still in the original root ball, which can dry out quickly. Check these plants frequently and water both the original root ball and the surrounding soil if either is dry. Even plants that have been in the ground for 3 years still need to be tended to and need extra water during stressful times. They have not yet developed an extensive root system.
Remember to always check soil moisture before watering. A plant’s metabolic processes slow down in extremely hot temperatures. Plant processes like respiration and transpiration increase as temperature goes up to a certain point. Once it passes that point, these processes plateau or slow down. This means the plant may use less water at 95 F than 85 F, assuming water is not lost to evaporation.
During a heatwave, you should apply water directly to the areas needed. A high-quality watering wand that is 24 to 36 inches long will help to reduce bending and stooping while you water and allow you to reach the base of the plant to water efficiently. Avoid any spray nozzles. Drip Tape or a pot dripper are other effective options, as they run directly along the ground and will apply water directly to the root zone. Remember, plants do not take in water through their leaves.
Mulch
Covering the soil with organic materials like wood chips, grass clippings, clean hay or straw, or leaf litter can help hold water in the soil by reducing evaporation. It has the added benefit of shading the soil to keep the root zone cooler.
Shade
Plants in containers can be moved to a shady spot during a heat wave. This reduces the light that hits the plant and container, keeps temperatures lower, and reduces water loss. There have been incidences of “pot fires” when peat moss in a pot has gotten so hot it ignited.
If you are not able to move plants into the shade, then bring the shade to the plant. Use shade cloth, screening, or even white sheets to reduce the amount of light hitting the plants and the surrounding soil. Secure shade covers on a few posts or a wire hoop frame several inches over the plant. Putting up a shade cover helps the soil and plants stay a few degrees cooler while reducing the amount of moisture lost. Shade cloth comes in various densities that can block different levels of light. For many plants, starting with 30% to 50% shade cloth is sufficient. Different densities can be layered to provide even more shade. Any shade covering should stay above the plant and not come in direct contact to avoid retaining heat and potential leaf burn.
Stress
Just like us, plants experience stress when they are in the heat. In extreme heat, plant processes slow down. Adding fertilizer promotes growth that the plant cannot support, leading to additional stress.
Planting, transplanting, and propagating are stressful on plants at any time of the year. Avoid adding additional stress to your plants by not doing this during a heat wave. The best practice is to wait until the temperatures subside to plant or propagate.
Many plants will stop blooming during extreme heat. Removing the spent flowers can improve the plant's appearance, keep plants from spending precious resources on fruit and seed development, and set the plant up to bloom again once the heat wave passes.
You
When gardening during excessive heat, it is important to take care of yourself as well. You can do this by working early in the morning when it is cooler. Be sure to carry water with you and wear sunscreen and a hat. As you are working, remember to take breaks to allow yourself to cool off. It’s important to know your body to ensure you are not overheating.
It is important to know the signs of heat exhaustion and heat stroke.
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Signs of heat exhaustion:
If you exhibit any of these signs you should find a cool, air-conditioned area as soon as possible. Drink water if fully conscious. Take a cool, not freezing cold, shower or use a cold compress. |
Signs of heat stroke:
If you exhibit any of these signs you should call 911. Action should be taken to help cool the person until help arrives. |
Jesica Streets, WVU Extension ANR Agent – Tucker County
Jody Carpenter, WVU Extension ANR Agent – Barbour County
References
Chernoh, Erica, and Kym Pokorny. “Tips for Gardening in Extreme Heat"
Hoidal, Natalie. “Hot Weather Gardening Tips.”
Steil, Aaron. “Managing the Garden in Extreme Heat.”