Now that we’re in the thick of summer, heat is a serious factor for plants, animals and humans. For people, staying hydrated, wearing long sleeves and pants, using a wide-brimmed hat and sunscreen and taking breaks in the shade can prevent heat exhaustion. But those strategies don’t work for plants, so we need a few tools of our own to help them cope.

In addition to extreme temperatures, our low humidity makes growing conditions even more challenging. If we irrigate in the morning, much of that moisture can evaporate by afternoon as the dry air pulls it from the soil. This evaporation stresses both the plants and the person doing the watering and increases the water bill for anyone using domestic water.

CONSERVE MOISTURE

One way to conserve moisture is by applying mulch. Mulch forms a protective barrier over the soil, reducing evaporation, keeping the ground cooler and helping retain moisture for both plants and microbes. It also means you won’t need to irrigate as frequently.

Leaves and straw are common mulching materials that break down over time, adding organic matter to the soil. I prefer straw because it locks together and stays in place better. I’ve even used old, moldy hay bales that were no longer suitable for livestock—ranchers are usually happy to give them away. Cardboard also works well, especially in tight spaces between plants. Avoid using cardboard boxes with colored ink, as the pigments may contain harmful chemicals. However, boxes printed with black ink are generally safe, since most black inks are now soy-based. Newspaper can also be effective if you use at least four layers and weigh it down with rocks.

SHADE SOLUTIONS

Black shade cloth absorbs heat, which may benefit cooler areas, and it blends more easily into the landscape.

Another challenge of high elevation is that we’re nearly a mile closer to the sun. Many vegetable plants don’t tolerate temperatures above 95 degrees Fahrenheit. They may slow or stop production in response to heat stress. Professional growers use shade cloth to keep the temperatures cooler and improve yields.

Shade cloth filters the sun’s rays while still allowing photosynthesis. It prevents sunscald on tomatoes and peppers and can even enhance the color of cut flowers. For home gardeners, 30% shade cloth is ideal for heat-loving crops, while 50% shade works better for cool-season greens like lettuce and spinach.

Bootstrap Farmer (Boot strapFarmer.com) sells shade cloth in garden-friendly sizes. Some growers install T-posts and drape shade cloth overhead, then run a misting system on an intermittent timer to cool the air around the plants. 

White shade cloth reflects light and keeps plants cooler, making it better for warmer climates and flowering plants.

White shade cloth reflects light and keeps things cooler, making it better for warmer climates and flowering plants. Black shade cloth absorbs heat, which may benefit cooler areas, and it blends more easily into the landscape. You can attach it to posts or stakes with shade cloth clips with hinges. Or, place a small rock under the edge of the cloth, tie twine around it and secure it to a post. This won’t tear the cloth and allows better tension, so it doesn’t flap in the wind.

You can also try stretching lace tablecloths (about 30% shade) over tomato cages or securing burlap (about 50% shade) over wire hoops with clothespins. This gives the same effect but is less costly.

FEEDING FOR FAST RESULTS

Finally, remember that healthy plants will always tolerate heat and environmental stressors better than nutrient-deficient ones. Midseason is a great time to add fertilizer. Granular fertilizers work well in spring but take months to break down. In July, use liquid fertilizers that reach roots within days. You can buy them or make your own to pour around the base of the plants.

Even better, apply liquid fertilizer directly to the leaves for fast absorption through their pores, or stomata. This foliar feeding method can deliver nutrients in under an hour—just be sure to spray in the early morning or evening, when stomata are open.

With a little planning and care, your garden can thrive—even in the summer heat. 

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