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The Honolulu Advertiser
Posted on: Friday, September 1, 2006

Hot, dry weather calls for special attention to garden

By Joel M. Lerner
Washington Post

There are things you can do to reduce the impact of hot, dry weather and create a garden climate where plants will thrive. Some of these practices are behavioral, having to do with watering and maintenance; some are structural, concerning design and plant choice.

From a behavioral standpoint, you need to know that plants have to be watered, even if it has rained recently. How do you know when? The best way to check moisture is to stick your finger in the soil and see if it's moist. If you don't want to get dirt under your nails, use a moisture meter, available at garden and home-improvement centers. They are not as accurate, though. Check several places; different areas have different drainage rates. If you can't feel moisture, water. Don't just sprinkle plants; provide them with a good long soaking so water can penetrate to the roots.

When you water, be efficient. Water plants in the early morning or early evening, when temperatures are cooler and winds are lighter, to minimize evaporation. If you water later in the day, make sure foliage has enough time to completely dry. A soaking hose is better than a sprinkler for gardens; a timed sprinkler system is ideal for turf. Although expensive to install, it can save water in the long run.

If you use movable sprinklers, check frequently and adjust so that only your lawn or garden is being watered — not the sidewalk. Don't waste runoff. Direct downspouts and other runoff sources toward shrubs and trees. Use a rain barrel under a downspout to collect water for the garden.

You can also cut down on water consumption by reducing the amount of lawn you have. Turf is used to going three weeks to a month without rain, but after that, it needs to be soaked — as periodic thunderstorms do on the prairie.

Whatever lawn you have, leave it a little taller when you mow (2 1/2 to 3 1/2 inches). Longer grass shades root systems and holds soil moisture better than a lawn that's been closely clipped. And leave the clippings on the lawn. That also helps hold moisture.

You can save water by collecting it from other sources and directing it to the garden. Some sources of second-hand household water are air conditioners, dehumidifiers and fish tanks. (Use the latter sparingly, as it's high in nitrogen and will encourage growth.)

USE GRAY WATER

Gray water, such as bath, dish and cooking water, also can be used in the garden. Put it on the soil, not on the foliage. Don't use water that contains bleach, detergent or fabric softener.

Appropriate use of mulch also can slow evaporation of water from plants' root zones. Use organic mulches, such as compost or bark. Compost incorporated into the soil will hold moisture.

Keeping weeds out of the garden also will help. They use moisture that could be available to the plants you do want.

Structurally, gardens can be designed and planted to withstand warmer, drier conditions.

When you choose plants, follow the principles of water-efficient landscaping, or xeriscaping. The word means planting for dry conditions, but it's come to mean installing drought-resistant plants and delivering water to them efficiently. In general, native plants are the best choices, as they already are adapted to local conditions. When you replace plants in an established garden, choose those that will withstand drier conditions.

Design for shade and coverage. Evaporation from plant leaves has a cooling effect on the environment. Ideally, trees, shrubs, perennials or annuals should cover 75 to 80 percent of the soil. Group plants with similar water requirements.

It may or may not be true that talking to plants helps them grow better, but remember that your plants are constantly talking to you. Wilting and browning foliage can mean a plant is not receiving enough water or that it has "wet feet" and is suffocating. If a plant doesn't thrive no matter what you do, there is a good chance it is planted in the wrong place.

Joel M. Lerner is president of Environmental Design in Capitol View Park, Md., and author of "Anyone Can Landscape" (Ball, 2001). Reach him at www.gardenlerner.com.