Dr. Cynthia Nazario-Leary: Protecting plants from the summer heat
The heat of the summer is here and we’re all feeling it, including the plants. Unlike people, plants don’t have the luxury of being able to move into an air-conditioned house or apply sunscreen. However, there are things we can do for our plants to make sure they can pull through a hot spell.
Watering correctly: Plants need a healthy and extensive root system to access water and stay hydrated during heat waves. Water at the base of the plant until the soil is saturated about a foot in depth to encourage roots to grow deeper in search of water rather than grow near the surface where they are more susceptible to heat and drying out. If a heat wave is coming, prepare your plants by watering the soil around the base of the plant, preferably early morning or early evening, when the air is cooler. Avoid watering plant leaves or stems, which can lead to fungal disease. Aim to water enough to keep the soil modestly damp (not soggy and never fully dried out). Resist the temptation to overwater! Always check the soil around your plant — if it is damp within an inch of the surface, pass on the watering. Plants sometimes wilt in the middle of the day from the severe sun and heat, but if the soil is moist, they will bounce back when the sun goes down. As tempting as it might be, when it’s super hot out, don’t spray down your plants in the middle of the day; water droplets on leaves turn into mini magnifying glasses that can cause scorching.
Supply some shade: Shade is an easy and effective tool to keep plants cool during hot days. By reducing the intensity of the sunlight and heat, plant stress is lessened, and the soil stays cooler and more moist. Shade also can prevent sunburning of fruit, commonly seen as whitish-yellow patches on fruit such as tomatoes or peppers. Anything that will block the sun and allow for good airflow will work as shade. When using shade for long periods (several weeks), use shade material that allows some sunlight to pass through (e.g., 30-40% shade cloth). For a shorter period, e.g., a day or two, you could use beach umbrellas or pop-up canopies; or if in containers, move plants to shady areas. If your shade cloth or sheet is a dark color, keep it several inches away from the plant as the dark color will absorb heat and, if touching, it can burn the leaves.
Mulch: Mulch can provide a protective layer for the soil and act as an insulator for plant roots. A good 3 to 4 inches of mulch material can help buffer against extreme temperatures (both hot and cold) and by reducing evaporation and runoff, can help retain soil moisture and lengthen the time between waterings.
Hold off on fertilizer: Applying fertilizer can stimulate new growth, and these younger shoots are more vulnerable to heat damage. Fertilizers also contain salts and, without adequate water, can burn plants and add to heat stress. Avoid applying fertilizer during high-heat days, but if needed, use a liquid fertilizer and apply it during the cooler part of the day.
Minimize pruning and leaf removal: Even healthy looking plants are going to be stressed in the heat. Like fertilizing, pruning or removing leaves can stimulate new growth, which is more susceptible to heat damage. To avoid added stress to the plant, wait until it’s cooler and the heat wave has passed to prune and remove leaves.
Special care for fruiting plants and seedlings: During extreme heat, plants may drop or cease producing flowers and fruit. Supplying longer-term shade for these plants, particularly in the hotter part of the day, will help support flowers and fruit. Young plants and seedlings with more delicate root and shoot systems also are more vulnerable to heat stress and damage. Right before and during high-heat days, check the soil moisture daily, supply shade or move these plants into shadier areas, and avoid transplanting.
Container plants: Containers tend to dry out faster and will need more frequent watering than in-ground plants. On hot days, check that potted plants and hanging baskets are not dry. Avoid dark-colored containers, which absorb heat and can cook a plant’s roots. Consider putting potted plants inside larger pots to give them some insulation, but make sure both pots have good drainage.
So, help your plants beat the heat this summer and keep them cool and hydrated!
To learn more about managing your Florida landscape, reach out to UF/IFAS Extension Alachua County’s office to speak with a Master Gardener Volunteer at 955-2402 or mag@alachuacounty.us, or visit Alachua County’s Florida-Friendly Landscaping Program webpage at bit.ly/AlachuaFFL.
— Dr. Cynthia Nazario-Leary is the Environmental and Community Horticulture Extension Agent for UF/IFAS Extension Alachua County. Contact her at cnazarioleary@ufl.edu or 955-2402.
This article originally appeared on The Gainesville Sun: Dr. Cynthia Nazario-Leary: Protecting plants from the summer heat
