Protecting Your Plants in the Summer Heat
While fanning yourself in the summer sizzle, remember that your plants are probably as uncomfortable as you are. When the thermometer passes 85 degrees, the heat is counterproductive to any plant, according to Steve Hollister, manager of Armstrong Garden Center in Irvine. Hot, dry weather can even be lethal for certain delicate plants.
Delicate Plants at Risk
Plants such as fuchsias, ferns, impatiens, azaleas, camellias, clivia (kaffir lily), shade palms, and hydrangeas prefer cool, shady conditions. Most of these plants are from moister environments, so the lack of humidity during hot months is especially drying and damaging. Plants in pots and hanging baskets are also at risk of drying out, as are lawns, which tend to be shallow-rooted.
For all plants, but especially delicate ones, ample water is critical in the heat. “Like all living things, a plant’s requirement for water skyrockets as the temperature rises,” said Hollister. “People often don’t notice a plant is thirsty until there are signs of wilting. Increase your watering before plants are injured.”
Gary Matsuoka, owner of Laguna Hills Nursery in Lake Forest, said, “To compensate for lack of water, the plant will shut down its leaves and begin using just one-tenth of the water it used before the drought. It’s important not to overcompensate afterward with too much water, because you will probably drown the plant. Water the plant once well, and then let it rest until the soil is dry again.”
Watering Tips for Hot Weather
In high temperatures, you can damage even healthy plants with too much watering. “Though fuchsias like moist conditions, they will develop a fungus in the root system if they are kept continually wet and soggy.”
With your finger or a moisture gauge, check your plants before watering to make sure they are truly dry. Some plants look wilted in the hot sun but are actually wet at the root zone. This occurs because the leaves are losing water faster than the roots can pump water to them. Blindly watering in this case interrupts the pumping of water to the leaves. Let the roots continue pumping uninterrupted, and the plant should perk up by the end of the day when the sun is low.
One thing you can’t overdo is misting delicate plants. Misting greatly increases the humidity level around the plants and lowers the temperature, creating the type of habitat in which they thrive. There is a nozzle mist head known as Fogg-it that fits on the end of your garden hose and sprays a super fine mist on plants.
Other Protection Strategies for Delicate Plants
- Move container plants to cooler, shadier areas, such as under a patio or tree.
- Temporarily shade immovable plants with barriers like shade cloth or a movable plant that can withstand hot sun.
- Program your sprinklers to water more frequently.
- Mulch to keep plants moist. Good mulches include homemade compost, planter mix, and peat moss for acid-loving plants such as azaleas.
- Give your lawn enough water. During hot weather, grass should be watered for three, five-to-10-minute periods about an hour apart. If you water too much at once, 95% of the water doesn’t soak in.
To make sure your lawn is getting the water it deserves, test your sprinkler system by placing empty cans throughout the yard. Turn on the sprinkler for two minutes, then turn it off and check the water level in the cans to ensure the water is evenly distributed.
Use a plant anti-transpirant. Most of the water taken up by plant roots is lost when the leaves transpire. Anti-transpirants, such as the product Cloud Cover, reduce water loss through the leaves without compromising plant health.
- Avoid cooking the roots of potted plants by placing pots close together so they shade each other.
- Protect exposed branches and trunks of avocado and mango trees from sunburn by whitewashing them with light-colored latex paint.
- Be on the lookout for warm-weather pests. Spider mites thrive in dry, dusty conditions, so regularly knock them off with a strong spray of water on the plant leaves. Whiteflies must be treated with a pesticide using a five-day spray cycle. For caterpillars and worms, such as the tomato hornworm, use Bacillus thuringiensis (BT).
