In the Garden: Gardening in extreme heat
Table of Contents
The recent heat wave that swept across much of the country is a good reminder to take extra care of our plants and ourselves as temperatures climb. Extreme temperatures can take their toll even on plants normally suited to the growing conditions.
Many plants suffer when short- or long-term temperatures exceed 86° F. You will see withering, leaf and flower drop, stunting and more on heat stressed plants. The longer the heat wave persists the greater the risk of damage.
When daytime temperatures rise above 90°F and night temperatures remain above 70°F, blossoms drop and poor fruit development may occur on tomatoes.
Temperature extremes also impact pepper productivity. When temperatures climb to 95°F or higher, the pollen is sterile and flowers may drop. Small fruit may also fall from the plant during such hot spells.
We can’t change the weather, but we can help our plants cope when temperatures soar. Provide some midday and afternoon shade for plants struggling with the heat. Move containers to a shady location and use a patio umbrella or shade cloth suspended on hoops or stakes to provide your permanent plantings with a bit of relief.
Mulch the soil to conserve water, keep plant roots cooler, suppress weeds, and improve the soil as it decomposes. Spread a one-to-three-inch layer of leaves, evergreen needles, woodchips and other organic matter on the soil surface surrounding plants. The coarser the material, the thicker the layer of mulch needed. Pull mulch away from the trunk of trees and the stems of shrubs and other plants. You obtain multiple benefits from this one task while burning a few calories and strengthening your muscles.
Water plants thoroughly when the top few inches of soil are crumbly and moist. Plants will develop deeper roots able to access water from a larger area, making them more drought tolerant and pest resistant. Avoid frequent light watering that encourages shallow roots more susceptible to drought stress. Make sure new plantings, moisture lovers, and stressed plants are the first to receive a good, long drink.
Don’t overlook established trees and shrubs that need a helping hand during extended periods of hot, dry weather. Soak the area under the tree’s dripline when the top four to six inches of soil are crumbly and slightly moist. Provide ten gallons of water per inch diameter of tree trunk measured at 4.5 feet high.
Water early in the day, when possible, to reduce moisture loss to evaporation. Use soaker hoses and drip irrigation whenever possible. You’ll use less water by applying it right to the soil where it is needed.
Check container gardens daily. Water thoroughly when the top inch or two of soil is dry.
Take care of yourself when gardening, especially during hot weather. Try to work in the garden when temperatures are cooler and in the shady spots in your landscape. Take frequent breaks and drink plenty of water.
Cover up your skin with brightly colored, loose-fitting clothing made of densely woven fabrics. Wear a broad-brimmed hat to protect your skin and UV-blocking sunglasses for the health of your eyes.
Apply a broad-spectrum UVA & UVB sunscreen with an SPF of 15 or higher every day. Apply it 30 minutes before going outdoors and every two hours. You’ll prevent sunburn and skin damage while making it easier to return to the garden each day.
With proper care, you and your plants will be better able to withstand the summer heat.
Melinda Myers has written more than 20 gardening books, including the recently released Midwest Gardener’s Handbook, 2nd Edition and Small Space Gardening. She hosts The Great Courses “How to Grow Anything” instant video and DVD series and the nationally-syndicated Melinda’s Garden Moment radio program. Myers is a columnist and contributing editor for Birds & Blooms magazine, and her website is MelindaMyers.com, which features gardening videos, free webinars, monthly gardening tips, and more.
