When temperatures soar, we can head inside but our leafy friends cannot. Though plants have some ways of surviving the heat, we can help our gardens to live and grow in the current hot weather. These tips are primarily for vegetable gardens, but some information may benefit other gardens.
When temperatures get too high inside plants, the chemical tools needed for proper growth are damaged. Sometimes the green chlorophyll in the leaf is destroyed and plants cannot make food. Also, the plant uses food at a faster rate due to high temperatures. Plants can begin to starve and growth slows in the heat. High temperatures in combination with dry conditions can cause flowers and fruit to fall off. Tomatoes prefer temperatures between about 70 to 85 degrees and may shed flowers if temperatures are high (especially at night). How can we prevent plants from being damaged by the heat?
Vegetables require 6 to 8 hours of sun a day. We consider them to be full sun plants. However, if they are getting sun in the morning, you should be able to offer them some shade in the hottest part of the day. Of course, it would have been best to plan this at planting. However, for vegetables being planted now through September, look for a location offering afternoon shade. If plants are in pots, you can gently move them to an area that gets afternoon shade. Be careful not to knock off fruit when you move the vegetables.
If you can find shade cloth, you could drape up to 30 percent shade cloth over vegetable beds. Also, try not to prune vegetables like pepper and tomato in the summer. Allow the leaves to remain and to provide shade for the fruit. Fruits like tomato, pepper, watermelon and others may sunburn if they get too much direct sun.
Avoid fertilization in the heat unless you supply lots of water. The same goes for herbicides, though we should seldom use weed killers in vegetable gardens anyway. If you must use a fertilizer, use a liquid or slow release fertilizer until temperatures drop a little.
One of the main ways plants deal with heat is to cool themselves by evaporating water from their leaves. This is called evapotranspiration. We can think about this by imagining a plant perspiring. Plants release water which evaporates and cools them off.
To cool plants using water, apply water from 10 p.m. to 10 a.m. to reduce water loss. Apply ¾ inch twice a week if using a sprinkler or wet the ground at least 12 inches deep. Soaker or drip houses are great since they waste less water.
Mulches help as well. Apply a 3- to 4-inch deep mulch around plants. Make sure to keep the mulch pulled back from the base of the plant. Many mulches will work including pine straw, pine bark, wood chips, etc. Avoid using hay since it may contain harmful herbicides. Mulches conserve soil moisture and keep the roots cooler. Mulches are an important tool in surviving the heat.
Protect yourself in this heat. Your response to heat will depend on your overall health, the things you have eaten and drunk, medications you take and other factors.
Garden with a friend or have someone check on you regularly and bring you water. They should know and watch for symptoms of heat exhaustion and heat stroke and know how to treat these. Up to 20 percent of heat stroke victims die so take this seriously.
Drink before you get thirsty. If you wait until you get thirsty to drink, your body is already too dry! A good rule of thumb is to drink a glass of water for every 15 to 30 minutes of work in the heat.
Garden early and late in the day, when it is cooler. Take frequent breaks in a shady, cool place. Wear light-colored, loose clothes and cover your head and neck. Wear sunscreen. If you have not been working in the heat, it may take you 1 to 2 weeks of working in the heat daily to get used to the temperatures. For more information, see this article where I found much of this information - http://tinyurl.com/826dkdx.
Willie Chance works with the University of Georgia Center for Urban Agriculture and helps to train the turf and landscape industry.