4 Ways to Rescue Your Plants From the Heat Wave‏

Watering plants with a hose and aerator attachmentIt's best to water your plants by hand, with a garden hose and an aerator attachment. Image: estherase/Flickr

Summer’s triple-digit heat is threatening to fry the trees and shrubs you’ve spent all year tending. Here are the plant-watering tips you need to keep your plants healthy.

You can’t turn off the sun. But you can turn on a spigot and save your plants by watering wisely and well.

“It’s decision-making time,” says Scott Aker of the National Arboretum in Washington, D.C., where temperatures this summer have reached 105 degrees.

Your first decision? Let your lawn go.

“Turf grasses are programmed to go dormant in heat as a protective measure,” Aker says. “As soon as we get rain and the weather cools, they’ll get green.”

Also, give your vegetable garden its last rites. Tomatoes and peppers don’t form in heat above 95 degrees, so watering them now will keep the foliage alive, but you won’t see any fruit until September or October — if you’re lucky.

Jim Sutton of Longwood Gardens in Pennsylvania has nursed shrubs and trees through several heat waves this summer. He offers four vital tips on how to help your landscaping beat the heat:

1. Recognize stress

Many stressed plants look thirsty. Green foliage turns grey and droops; blossoms and leaves fall to the ground in a desperate attempt to save the shrub. A deep watering often brings a plant back, or at least saves it so it’ll bud next year.

But if leaves are crispy, or the plant continues to look parched in the evening, then it’s reached a permanent wilting point: The point of no return. However, its death need not be in vain. Add your hapless plant to the compost pile to someday nourish its luckier neighbors.

2. Triage. Stat!

In triple-digit heat and drought, save what you can in this descending order:

  • Newly planted shrubs and trees, vulnerable and pricey landscaping
  • Perennials: Cut blossoms and stalks, which gives plants a rest and raises chances of returning next year.
  • Established trees and shrubs, at least two years old, which have deep roots.
  • Container plants: Move them onto a porch or under a shade tree.
  • Vegetable gardens
  • Lawns

3. Watering 101

Here’s a watering rule of thumb: Water deep, not often. Water should reach 8 to 12 inches down, creating a well of water for plants and trees to draw upon in high heat. To determine if you’ve reached your mark, press a large screwdriver into the soil: If it meets resistance, keep watering.

Hand-watering with a garden hose and aerator is best. Count to 10 as you water the base of plants. Move and repeat. If you have lots of property to water, then use a sprinkler, but adjust it so it doesn’t waste overspray on driveways and walkways.

Tree gators (plastic donuts or sacs that slowly release water onto tree bases) and drip hoses are good helpmates, too.

Water in the early morning: Not 7 a.m. when you usually roll out of bed, but when the sun rises at 5 a.m. or 6 a.m. However, don’t get fixated on watering in the morning. If water restrictions require only evening watering, soak ‘em good and don’t fret about fungus forming on leaves that stay damp throughout the night: A little powdery mildew won’t kill your shrubs, but dehydration will.

4. Mulch is your friend

If you didn’t mulch in spring, do it now. Mulch will keep moisture in the ground and suppress weeds, which compete with landscaping for water. If you haven’t mulched, water thoroughly, then add mulch to a depth of 3 to 4 inches.