Hot, hot, hot! Gardening info for this summer’s heat wave
August 2, 2012
The weather has been very warm this year. In fact, the temperatures in July were the second hottest on record. When all of that heat is combined with the driest summer in decades, nature has created a perfect storm for stressed gardeners, landscapes and plants. So, should we all just throw in the garden trowel? The answer is no. As tempting as it may seem to let everything slide and dream of a cooler and wetter autumn, there are things that we can do to help our plants and gardens cope with the current conditions. And for us gardeners, there is always lemonade.
Let’s begin with the bigger picture. Minus a few exceptions of course, your landscape is equipped with some pretty good coping mechanisms. The first decision you’ll want to make is about your lawn. Do you irrigate or not? When you stop watering in this heat, turf will go completely dormant, awaiting fall rain and lower heat indexes before it greens up again. For sure, it looks dreadful for a couple of months, but the roots are perfectly fine. If you decide that summer is just not the same without a lush green lawn, make sure that you irrigate thoroughly but less often. An inch of moisture a week is what you need. Just choose to water or not, and stick with your choice. A quick word about planting new lawns-wait until it cools down. Grass seed will just bake at this time of year and sod will have trouble establishing.
Trees and shrubs on the other hand, are not as adaptable as blue grasses and fescues. Even those plants that are well established in your landscape are very vulnerable to drought stress. As an general rule of thumb, soak the root zones of your trees and shrubs with a soaker hose for an hour or so, once a week. You are trying to approximate an inch of rainfall. Place a baking dish or a saucer under a section of the hose to measure the pressure if you are unsure. A regular hose, running at a steady trickle can be moved around the root area every 15 or 20 minutes. Even better is a root feeder. This low tech metal tube attaches to your hose and can be pushed into the soil to bypass the roots of your lawn, delivering all of that water to your woody trees and shrubs. You’ll want to keep this up until the temperatures moderate and the rains return. Don’t be alarmed if you notice early fall coloring or very heavy seed drop this next summer. Woody plants often respond to stress by producing extra seeds. Birth is probably nature’s eternal answer to death.
Now let’s consider perennial and annual plantings. These areas will require the same amount of moisture as your trees and shrubs-about an inch a week. What we do here on the property is to divide the gardens into zones that we assign days of the week. When it is simply dry, each border gets watered once each week, but when it is ho as well, some of the borders get irrigated twice a week. And you want that water to go to the roots, so try to use sprinklers that deliver as much moisture as possible to the soil. Keeping the leaves drier also helps to combat the perennial summer mildew and other fungal problems. And try to remember that wilting does not always equal dry soil. Some plants just suffer in the heat. Here the Four O’Clocks languish each afternoon, as do the Bigleaf Hydrangeas. If the soil is wet, sit tight. Once the sun starts to set, they bounce right back.
Vegetable and fruit bearing plants require regular watering if they are going to set and develop fruit worth eating. We have been watering our on-site vegetable garden twice a week. Most of our veg is doing well, though the squash plants are clearly suffering. In a perfect garden, we would use soaker hoses to keep the foliage dry, but when we are faced with hose shortages, we use an oscillating sprinkler. If you are doing the same, make an effort to water in the morning so that the leaves dry before sunset and you are losing as little moisture to afternoon evaporation as possible. Keep up with the weeding and consider mulching around the plants to slow the exposed soil’s tendency to drying out.
Lastly, consider your containers. Imagine you are an annual of some kind, let’s say a Coleus. You’re trapped in a pot with dry soil anchoring your feet, your hatless head exposed to the pitiless sun and your arms and body buffeted by the hot southern winds. That’s the life of a container plant this summer. Be us to water them every day, twice when the temperature exceeds 90 degrees. Minimize use of foliar fertilizers. And maybe move them into the shade on those really sultry days.
We’re really not trying to anthropomorphize the plants, but put yourself in their shoes. I mean, roots. You’re thirsty, they’re thirsty. You’re hot, they’re hot. So keep them, and yourself, comfortable until September. Autumn is coming.