How Gardens (and Gardeners) Can Weather the Dog Days of Summer

Get out in your garden after the first wave of really hot weather and examine each of your shrubs and plants (or groups of plants if you have a large landscape). Don’t overlook plantings that are mostly in shade; even most so-called “shade plants” can suffer from lack of consistent watering.

First, learn to recognize signs of drought-stress. The heat of May through July is a lot more damaging to plants than that of August through October, simply because the days are getting shorter during that latter period. Besides general wilting, plants that are stressed out from too much heat and/or not enough water can display some or all of the following symptoms:

• curling/rolling of leaves
• yellowing and browning of leaf margins and tips
• stunted growth of leaves and branches
• sudden/rapid dropping of leaves, fruit, or flowers (including needles on conifers and evergreens)
• increased pest activity, including damage caused by spider mites and borers

Water Wisely

Second, don’t rely on Mother Nature for all your garden’s watering needs. Farmers have irrigation systems for a good reason: they know that rainfall sometimes just isn’t enough. When daytime temps hit 90¬∞F, it’s time to give plants some help.

Use drip irrigation systems or soaker hoses wherever possible, because the water will be targeted right at the roots instead of evaporating off the leaves. Standing around waving a spray for a minute or two in the general direction of the plant is just not going to cut it.

In addition, water in the early morning, if possible, since that gives plants a good start for the day and helps reduce the incidence of fungal disease. Most plants need one gallon of water per square inch of root zone once a week. Watering thoroughly but infrequently is much better than watering lightly every day.

Third, set priorities. Large shade trees and mature shrubs can handle more heat- and drought-stress than younger and smaller plants and newly-seeded lawns. If you have new trees, shrubs, or ornamental annuals and perennials, make sure they get the water they need.

The Right Plant for the Right Place

Fourth, be smart about plant selection. Hydrangeas are lovely, but they seem to have a ‚”drinking problem,” that is, they live up to their name (hydra = water). Other water-hogs include most types of turfgrass, Ligularia, Tradescantia, New Guinea impatiens, and hosta. Plants to consider if you want to conserve water in your garden include yarrow (Achillea), sedum, portulaca, lantana, butterfly weed, gaillardia, junipers, Rose-of-Sharon (Hibiscus syriaca), perennial salvia, coreopsis, yucca, and black-eyed Susan (Rudbeckia hirta).

Fifth, mulch is a gardener’s best friend. Water penetrates grass and mulch-covered soil more readily than bare soil; bare soils high in clay content often bake in the sun to form a hard crust that sheds water instead of absorbing it.

Finally, recycle! Rain barrels are a terrific investment, and you can use so-called ‚”gray water” — e.g. from washing dishes and clothes — without too much concern unless you use lots of bleach. Most dishwashing and laundry detergents, if used in moderation, are diluted enough by the time you’re finished the process that they really won’t hurt plants.

But don’t use water that’s gone through a water-softening device, as the softening agents replace calcium and magnesium with sodium, which can definitely hurt plants over time. An excellent article on using gray water explains more about how to use recycled water in the home landscape.