Plants may need a lot of watering in the heat of July
It’s not called Death Valley for nothing. On July 10, 1913, the temperature in Death Valley hit a toasty 134 degrees, the hottest single day ever recorded.
Without question July is our hottest month, but it shouldn’t be. The longest day is after all June 21. It is all about inclination of the Earth. During the summer solstice, near June 21, we get greater sun exposure because the sun is directly overhead at noon. Even though the day is longest June 21, it is not until July that the Earth finally builds up more energy than it loses through radiation. So July, not June, is hottest.
It makes sense then that our gardens are at greatest heat stress during July. If it is hot and dry, you will need to water. Even if you water regularly, many vegetables will stop producing during heat waves. The leaves might even become sunburned. Tomatoes and peppers will drop their undeveloped fruits as well as lose their flowers.
In addition to watering, you can help eliminate heat stress with mulch. Keep a three-inch-deep layer of good organic mulch to cut down on moisture loss. The mulch also shades the soil and keeps the soil cooler. You can block the sun with shade cloth or even leafy tree branches.
Make notes for next year’s gardens, and be sure to plant some taller plants such as corn or tomatoes where they will shade leafy greens such as lettuce, arugula and chard. In the flower garden you can put in heat-tolerant plants such as cosmos (Cosmos bipinnatus). These are easily grown from seed and tolerate dry conditions as well as poor soil.
You can put up temporary shade cloth over crops, especially lettuce, spinach, arugula and all herbs. The shade can slow down their urge go to seed, known as bolting.
On the porch or patio, move potted plants out of direct sunlight. You may need to water potted plants twice a day during hot, dry days of July.
Most common lawn grasses don’t die during drought or high heat; they simply go dormant. This natural process is common in bluegrass, fescue, and ryegrass. They will turn brown but green up again in the fall when more rainfall and cooler temperatures come. Set your mower blades as high as comfortable, even up to 3 1/2 inches. The taller grass will shade and cool the soil beneath it, and your lawn will stand the heat better. Never fertilize your lawn during hot, dry weather; you could actually kill the grass.
If you do need to water your lawn, you will need to use at least an inch of water per week. During high heat, double that to two inches of water a week. The best solution is sometimes the easiest, and it may be best to just let your lawn go dormant. It will naturally return to its green color on its own this fall.
As a bonus to the high heat of July, your grass probably has stopped growing so you don’t need to cut your lawn at all. Relax, and don’t get crazy with the heat.