Wise Watering in Dry Times

We gardeners don’t need a weatherman to know it’s been an abnormally dry year in the Charlottesville area. Federal weather data confirms what we’re seeing in our yards: total precipitation for our locality is around four inches below what we would typically receive by now. As you reach for your garden hose to make up for Mother Nature’s shortfall, follow these pointers to ensure you are using water wisely.

Watering a Thirsty Garden

Test for dryness before you water. Before turning on the spigot, dig three to six inches into the soil with bare fingers to test for dryness. Or try this: if the soil cannot be formed into a ball, it’s too dry to provide water to plant roots and you know it’s time to water.

Water only as much as needed. Different plants have different water requirements, but in general, established gardens need an inch of water per week to stay healthy. The simple tuna can water gauge can help you meet that target. Bury an empty tuna can up to the rim in the garden and check it as you are watering. When it fills up, you have provided the water your plants need for a week with no rainfall.

Water at the soil level. Most of the water taken up by plants comes through their roots rather than leaves. With a wand or nozzle attached to your hose, water plants at the soil level. This helps you reach the plants’ root zone and minimizes wetness on foliage, which can increase the risk of fungal diseases.

Water deeply. Instead of watering lightly every day or so to reach the weekly one-inch mark, water deeply and less often. Deep watering should reach at least four to six inches into the soil and will build strong root systems that make plants more drought resistant. Light watering, by contrast, leads to shallow root growth and weaker plants. However, avoid overwatering. Persistently soggy soil will rob plant roots of the oxygen they need.

Check potted plants and new plantings every day. Outdoor plants in containers need deep watering, too. Check pots each day for dryness. If needed, provide water until it begins to flow out the drainage holes at the bottom. But be careful. Overwatering of container plants can lead to root rot and other diseases. Seedlings and recent transplants will need frequent watering until they are established. Water them gently every day until their roots take hold and signs of growth appear.

Water in the morning. Watering during the heat of the day is inefficient and leads to excessive loss of water to evaporation. It’s better to water in the morning, ideally before 9 a.m. Watering in the cool of the evening will also avoid excessive evaporation, but foliage is likely to remain damp through the night, making plants more vulnerable to diseases and other problems.

Apply mulch. A two- to three-inch layer of organic mulch, such as shredded leaves, bark, straw, or even grass clippings, will help keep garden soil moist and cool while suppressing weeds that compete for water. As it breaks down, the mulch will add organic matter to the soil and improve its ability to hold moisture. You may need to pull back mulch while watering to make sure you’re reaching the root zone.

Install a slow irrigation system. For larger flower and vegetable gardens, installing a system of soaker hoses or drip irrigation can be a good investment, reducing water use by as much as 50 percent. These systems deliver water slowly and efficiently to the plants’ root zone with minimal loss to evaporation or runoff.

Install rain barrels. Rain barrels attached to your home’s downspouts also help to reduce runoff and can provide a reservoir of water that will help keep your garden going during dry spells.

But What About My Lawn?

Right now, your parched lawn is probably losing color and may look like it’s dying. Don’t panic. An established lawn composed mostly of cool-season grasses, such as tall fescue, can withstand three to six weeks of dry conditions without watering. Warm-season grasses, such as Bermuda grass and zoysia grass, are even better at withstanding hot, dry weather and require no irrigation.

During a long summer dry spell, lawn grass enters a state of semi-dormancy, directing energy to crowns and roots rather than leaves and shoots. If you’re worried your grass may have died, give it a tug. If it doesn’t break loose, it’s still alive. It will green up when the days grow shorter and when cooler and wetter conditions return.

When your lawn is in a semi-dormant state, avoid walking or driving on your grass. Increase mowing height (if mowing is even needed), and do not apply fertilizer. If you must water your lawn, for aesthetic reasons or to help it withstand foot traffic, follow these pointers to reduce waste and improve results.

Time your watering. As in the garden, the rule of thumb is to apply between one and two inches of water a week to your lawn, minus any rainfall. This can be hard to achieve all at once. Use a variation on the tuna can technique—placing several cans around the lawn—to measure how long it takes to fill the cans a half inch, and then water for that length of time twice a week. EPA advocates this humble but effective method in its WaterSense watering tips.

Get to the roots. Again, water in the morning to avoid evaporation, and water deeply to reach down to the roots—three to six inches into the soil. After watering your lawn, check back a few hours later and dig a small, six-inch hole to make sure you have supplied enough moisture. Allow the soil to dry out a bit between waterings. Frequent, shallow watering of the lawn encourages shallow rooting and the germination of weed seeds, while also increasing the risk of disease and insect problems.

Water your lawn, not your driveway. Place and adjust sprinklers to keep water on your lawn and away from paved surfaces, where it can become wasteful runoff that threatens nearby waterways. Also, select a lawn sprinkler that sprays low across the ground rather than up into the air. If water starts to run off your lawn while you are irrigating, reduce the flow or take a break. Let the water soak in, and resume watering later.

Design a Water-Wise Landscape

The best way to conserve water resources in your yard is to start with a water-wise landscape. Virginia Cooperative Extension offers an easy-to-follow set of recommendations for “working with nature and natural forces (such as rainfall) to create an aesthetically pleasing, livable landscape, while using less water from the local supply.” These include:

Improve the soil. Adding organic matter to the clay soils so predominant in our area will help them absorb water faster while reducing runoff and erosion. Incorporate two to three inches of compost, shredded leaves, or other fine organic material into the soil each year.

Select the right plants. Choose plants—particularly native plants—that can thrive with little or no additional water. If you select plants with high water demands, group them together so they can be easily watered.

Limit your lawn. Plant turf grass only where it will be beneficial, such as play areas for children. Select turf grass species suitable for our climate, and design grassy areas to make watering efficient. For example, avoid grass strips between the street and the sidewalk; when they are irrigated, most of the water will fall on the pavement.

Here are some other resources that will help you use water more wisely:

“How to Water Wisely This Summer,” from Karen Zaworski for the Chicago Botanic Garden

“Care of Annuals and Perennials,” from University of Maryland Extension

“Watering Lawns,” from University of Maryland Extension

“Summer Lawn Management: Watering the Lawn,” from Mike Goatley for Virginia Cooperative Extension

“Water Conservation Tips for Irrigating Lawns,” from Penn State Extension

“Water-Smart Landscapes,” from U.S. EPA

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