How to garden during a 100+-degree heat wave

Little Ladybirds Cosmos

Don’t.  Seriously, don’t try to do any gardening when it’s as hot as it is in my part of North Carolina right now. We are predicted to see — and feel — a string of at least five days with highs hovering around 104 or so; humid nights may drop into the upper 70s if we’re lucky. No rain, of course,  barring the iceberg’s chance in Hades of a random thunderstorm.

I chose the photo above, because the warm colors of the Cosmos flowers provide at least a faint reflection of the sun’s intensity. They have turned out to be lovely little annuals; I hope they survive the heat wave.

Several visitors to my blog have lately found their way here by searching on how to garden in this heat. My advice follows.

  1. Seriously, don’t try to do anything significant when it’s this hot. That means, no weeding or planting. Don’t do anything that will disturb the soil, because such disturbances will release soil moisture into the air and harm roots of plants you’re trying to help.
  2. Do all your watering and harvesting before 7:00 a.m. If this means you must get up an hour early, so be it. Plants will best be able to withstand handling from picking before the sun reaches full power. Watering just after dawn gives the plants time to absorb the moisture before the searing sun compounds the stress they’re under. Watering late in the day in this heat and humidity increases opportunities for fungal diseases and visits by snails and slugs. Water in the early morning, period.
  3. Water plants deeply and not every day. Although it’s labor-intensive, the best way to water during heat waves is by hand. You take the end of the hose, position it at the base of a plant, and add water until the ground stops absorbing it. That’s the ideal. If you are like me and water is a limited resource, time the amount of water each plant gets, and give the most water-sensitive plants more water than the tougher plants. In my garden, squashes and beans need more water than tomatoes and peppers, and peppers need less than the tomatoes. My remaining squashes (I’m down to four now) get 1.5 minutes of water; beans get 2 minutes; tomatoes are surviving on 1 minute; peppers have been getting 30 seconds of water every other day.
  4. Don’t overwater. Now that the heat wave is fully here, I plan on cutting back watering to every third day. In this kind of heat, vegetables go into a holding pattern as they fight to simply survive. Tomato flowers and other veggie flowers don’t set fruit when daytime temperatures exceed 90 degrees. Fruits won’t expand much beyond their current sizes; the plants just don’t have the resources to grow.
  5. Be proactive about harvesting. Fruits that reached a mature size before the heat set in will continue to ripen if the plants can hang on. It’s important to pick the fruits as they are ready to reduce the likelihood of fungal diseases and insect invasions.  By harvesting just after dawn, you minimize stress on plants, and maximize the viability and nutritional value of the fruit.

If you didn’t mulch your vegetable garden, you are going to have a hard time keeping your plants alive. Old-fashioned row gardening, in which you hoe the weeds between rows, may have been how your grandmother did it, but it is not good for the soil, your plants, or your back. With the increasingly erratic weather patterns we now experience, and especially because those patterns tend to extremes like drought, heat waves, and floods (if you’re in Florida), the best way to ensure a productive garden is by using raised beds with mulched plants.

Mulching plants is hard work, I admit. But it is spring gardening work, when our weather is still bearable. The best mulch for a vegetable garden is last fall’s leaves. If you have a big yard full of trees like me, you can simply rake and save your own leaves. But if you live inside a city and have a smaller lot, every city I know of in my area collects leaves in the fall. In the spring, citizens can go get as many loads of composted leaves as they can carry, sometimes for a small fee, sometimes for free. When Wonder Spouse and I lived in Raleigh some 30 years ago, that city would deliver an entire dump truck load of leaves to your door — for free!

Gardening is always an act of faith, and sometimes, despite doing everything right, weather disasters happen, plants mysteriously die, a herd of rampaging deer storms and shreds your garden. You can never be sure that your hard work will pay off.

That unpredictability is part of why I remain an engaged, obsessed gardener after over 40 years of bumper crops and total losses, exquisite flowers and slimy slugs. I cherish the beauty intrinsic to the natural world all the more because I know it is fleeting.

Mother Nature is a temperamental teacher, and she does not tolerate fools. During this southeastern US heat wave, stay indoors where it’s cool, stay hydrated, and complete your essential garden tasks by dawn’s early light.

Rain dancing — although optional — is highly recommended.

Ornamental Care in the Heat

I’m adding this addendum to yesterday’s post, because I can see from the searches hitting my blog that folks are frantically trying to figure out how to keep their ornamentals alive. Here’s my quick-and-dirty advice.

If you are a lawn lover, don’t mow yours until the heat wave breaks. If that means it’s a little shaggy in spots, that’s still better than exposing freshly cut grass to the searing heat we’re getting. Stick to your regular watering schedule if your lawn is accustomed to supplemental water.

If you planted trees, shrubs, or perennials this spring, they will need supplemental water during the heat wave, if the ground around them is dry. Our clay soils hold water a surprisingly long time. Stick your fingers below the mulch layer to assess the moisture content of the ground around the plant. If you didn’t mulch these newbies, do so as soon as you can. Without mulch, they don’t have much hope of surviving.

If your new ornamentals are planted in full sun, they will wilt in the mid-day heat no matter how well-watered they are. This is an adaptive mechanism of the plants. If they have healthy, moist root systems, they will perk up when the sun goes off them. If your new plants aren’t adapted to full sun but they are getting a lot of sun, try improvising some shade for them somehow. It might improve their survival chances.

Don’t fertilize any plant during a heat wave. The roots will be damaged. Don’t spray any plant during a heat wave. You will do the leaves more harm than good. Your goal is to minimize the stress they are under by protecting them from the sun if you can, and by watering deeply once a week to encourage deep root growth. Shallow roots arise when plants are watered frequently for short periods. Such root systems are much more easily damaged during heat waves/droughts.

Good luck, folks!

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