The first heat wave came early this year, with record 90-degree temperatures in June, and we're far from the dog days of summer.
That means our gardens and lawns, shrubs and trees have been especially thirsty. Luckily, there are a few tricks to dealing with the heat — one of which allows you to slack off a bit. Follow these key tips for keeping your roses blooming and your grass growing when it's a scorcher out there:
Water in the morning. Rise and shine! Watering your lawn and garden beds before the sun is at its most intense means more water will make its way to the root systems rather than evaporating at the surface. The earlier, the better. According to the U.S. Environmental Protection Agency, the sun's rays are strongest between 10 a.m. and 4 p.m., so avoid watering during this period, if possible. If your city has a watering ban, follow it.
Mow grass high. It may be against our lawn manicuring instincts, but a dry spell gives you permission to grow your grass taller than usual before cutting it. Aim for grass that is 3 to 4 inches high during a heat wave.
Taller grass promotes deeper root growth and shades the crowns of the grass plants. Also, make sure lawn mower blades are sharp for a clean cut, further locking in moisture.
Water pots slowly. It's about quality, not quantity. If potted plants are watered too quickly, water will overflow and the excess could sit in the pot plate and cause root rot. Make sure there are holes for drainage at the bottom of your garden pots. If not, drill holes into the bottom.
Perform a moisture test. To see if your potted plants have been watered enough, check the moisture level. Do this by using your finger to see how far down the moisture in the soil is until it feels dry. About 1 to 2 inches is standard.
Take a hiatus from pruning and fertilizing. While instinct might be to prune or fertilize as a way to nurture, it will cause stress. Julie Weisenhorn, University of Minnesota Extension horticulture educator, explains that our lawn grasses are cool season grasses and grow most actively during spring and fall. Hold off fertilizing until the weather cools and you see active growth.
Hold off on transplanting. Plants like shrubs, trees and flowers are stressed by the heat and drought conditions. Transplanting adds stress to plants, so wait to do any transplanting until we get some rain and temperatures head downward.
When it comes to dividing perennials, a good rule of thumb when pruning and mowing is to remove one-third of the plant at a time. "Cutting off too much green parts of a plant at one time reduces the ability for a plant to photosynthesize and produce energy for plant growth," said Weisenhorn. For more information, visit the University of Minnesota Extension's Planting and Growing Guide page online.
Beware of weed spraying. Weisenhorn added this key piece of advice: "Do not spray weeds when temperatures are above 85 degrees. When combined with heat, herbicides can convert to a gas and drift onto non-targeted plants. Herbicides also are not as effective when weeds are under heat stress."
Before using any chemical, read and follow the label instructions. Pay attention to conditions like air temperature and other restrictions for that particular product. "You can always remove weeds by digging them out," she said.
Nancy Ngo • 612-673-4892
