The start of July was anything but subtle. Temperatures soared across North America with heat indexes exceeding 100°F in our region. You know it’s bad when northern Alaska, which has an average July temperature in the mid-40s, issued a heat advisory for temps up to 85°F. Unfortunately, this isn’t an anomaly. It’s becoming the new normal as the occurrence of heatwaves in the US has doubled since the 1980s.
Summer is supposed to be the time for gardeners to shine, but it’s important to know the dos and don’ts of yard work during a heatwave. Like us humans, plants require some babying during scorching heat. Avoid these mistakes to keep your growing season on the right path.
1. FREQUENT BUT SHALLOW WATERING
Your plants may benefit from multiple waterings during extreme heat, but the most important thing is to water deeply. Roots will grow deeper in search of water if you give them a proper soak and water less often. Plants that receive more frequent but shallow watering can end up with weak roots that stay near the surface level, making them more susceptible to drought and nutrient deficiencies. It’s best to water in the morning or evening rather than the peak heat of midday when the water will evaporate faster, giving roots less time to absorb what they need. As we previously mentioned, it’s okay to give them extra water as needed during heatwaves! Just remember to focus on quality over quantity, and use a moisture meter when in doubt.
2. WATERING LEAVES
Plants drink through their roots. Sun scorch caused by watering leaves is now regarded as a myth by experts. However, it’s still not recommended to water the leaves because the longer leaves stay wet, the more susceptible your plants are to fungal diseases. In turn, fungus and mildew can make it harder to fight pests. This is also why proper spacing is important in the garden. Better air flow allows foliage to adequately dry after rain.
3. GOING OVERBOARD ON NUTRIENTS
Hold off on the fertilizer when temps surpass the mid-80s. Feeding your plants encourages foliage growth, but plants naturally try to slow growth during extreme heat to conserve energy and moisture. This can put undue stress on your garden that may cause plant burn and rapid evaporation. If you can’t put off fertilization, slow-release fertilizers are a safer option than fast-acting varieties. Compost, worm castings, or fish emulsion gradually break down and are less likely to damage roots.
4. PUT THE SHEARS DOWN
Sometimes plants need a haircut to remove disease, promote new growth or improve airflow when they’re overgrown. However, that can wait until the temperature drops. Pruning during a heatwave exposes tender new growth and inner branches to intense sunlight. This can result in sunscald. Additionally, your plants are already stressed and trying to conserve moisture during extreme heat. Water loss from a fresh cut and directing the plant’s energy away from survival toward this new growth can cause shock.
5. CUTTING GRASS TOO LOW
Like pruning, hacking away too much grass can lead to severe turf stress. Never remove more than 1/3 of the grass blade in one mowing session. During heatwaves, the shade from taller grass can protect its root zone and let it photosynthesize for more energy. Don’t mow when temperatures are above 85°F as this can stunt grass development.
6. INTRODUCING NEW PLANTS
Naturally, gardeners want to take advantage of greenhouse stock in the summer—but transplant shock is more likely when temps are above 85°F. Ideally, you should wait for a cooler day. If you must transplant, do it in the early morning or evening when the heat is less harsh. Make sure to thoroughly water your plant while it’s in the nursery pot. Saturate the hole after digging and place the plant once the hole has drained. Mulching will help retain moisture and keep the root zone cool.
Summer heat can be tough on your landscape, but a few adjustments can keep your greenery healthy even through the hottest stretches of the season. We hope you stay cool and keep your yard looking vibrant this summer!