Posted on: July 9, 2007
Cool Tips for a Hot Garden
Caring for plants in extreme heat requires shade planning, thoughtful watering and plenty of mulch
By Bev Bennett
CTW Features
If plants are sagging late in the day it means they’re not taking up water fast enough. If they fail to recover overnight, applying more water will only drown the roots.
If you wilt every time the outdoor temperature hits 90, think of what that blast furnace is doing to your garden. Just like humans, many plants suffer from extreme heat, especially when coupled with sparse rain.
Your tomatoes won’t set flowers when it’s excessively hot; your impatiens droop and lettuces may bolt ahead of schedule, say garden experts.
Don’t be discouraged. Although you can’t control Mother Nature, you can moderate the conditions your garden plants have to deal with.
“I’m in the Central Valley of California. We commonly have temperatures up to 110 degrees,” says Pamela Geisel, the statewide master gardener coordinator with the University of California, Davis.
She and other horticultural experts have three basic strategies for protecting plants and keeping them well hydrated despite the high temperatures.
1. Water wisely
To avoid wasting water, install a drip tube to get the water to the roots while avoiding run-off, suggests Geisel.
Give plants a spritz in the afternoon to cool them off.
If plants are sagging late in the day it means they’re not taking up water fast enough. They’ll recover overnight when temperatures drop. However, if your plants don’t revive in the morning, something else is happening, according to Geisel.
2. Mulch
A layer of wood chips, compost or ground fir bark will help conserve water. Organic mulch has the advantage of breaking down and adding beneficial matter to the soil, says Geisel.
Be careful how you add mulch, says Martha A. Smith, a horticulture educator with the University of Illinois Extension in Macomb, Ill.
“You should add a two to three inch layer,” she says.
The problem comes from adding fresh mulch on top of previous layers.
“You can wind up with five to six inches of mulch without knowing it. Each year your mulch gets hot and dry and soaks up the water so it never gets to the soil,” Smith says.
Turn over the mulch every season for the look of new mulch without a heavy build-up.
3. Create shade
“I’ve been to garden walks where people put umbrellas in their gardens,” says Smith.
She shelters her hemlocks for about four weeks each summer when the sun is directly overhead.
You can also drape shade cloth over plants. This very thin fabric is available in some garden stores or through mail-order suppliers.
And as a last resort, you can whitewash your plants, just as Tom Sawyer whitewashed a fence.
“Make a very dilute concentration and spray it on the tops of tomatoes to prevent sunburn. The whitewash doesn’t block the sun the plants need.
“Wash off the whitewash before you eat the fruit,” says Geisel.
