Updated: Mar 7, 2019
Proper Watering and Creating a More Drought-tolerant Landscape
Put the right plant in the right place with the right soil. This is the #1 rule for any landscape project. Happy plants are healthy plants that will need less attention, water and care.
Your best guide for determining when to water is the plant itself. Wilting or a pale grayish-green color are the most common symptoms in plants needing water. Certain plants in the landscape -- such as annuals, herbaceous perennials, azaleas and rhododendrons -- need more water than others. By watering only those plants that need water, you not only will save water, time and money, you also avoid watering plants that do not need a lot of moisture.
Most ornamental plants in the landscape, once they are established, can go weeks without supplemental water. In fact, over-watering is a leading cause of problems with ornamentals. The Boxwood pictured here are suffering from root rot from poor draining soil.
To avoid run-off and water loss, apply water slowly to the base of the plant using a hand-held hose, drip irrigation, or soaker hoses. Do-it-yourself irrigation systems, available from most garden centers and home improvement stores, use 30 to 50 percent less water than sprinklers, and they can be attached directly to outdoor faucets.
The amount of water needed by an ornamental plant depends on the type of plant, the soil type, the amount of existing moisture in the soil, and the time of year. As a general rule, 6 gallons of water per 10 square feet of bed area or canopy area will saturate most soils to a depth of about 12 inches (the area containing 80 percent of the roots of most ornamental plants). Because water moves readily within the plant, you do not need to water the entire root zone. Twenty-five percent of the root area can absorb enough water for the entire plant. (from a University of Georgia article) The best time to water is at night or in the early morning. As much as 30 percent of the water applied during midday can be lost to evaporation accelerated by the sun. Sprinkler systems designed to water turf grass DO NOT put out enough water to saturate the root ball of newly planted shrubs and trees.
Steps to make your landscape more drought-tolerant
1. Improve the soil. This is the most important and most effective thing you can do to make your plants more drought-tolerant. Adding several inches of organic matter, and tilling it in whenever possible, improves the water holding capacity of clay. Plants will develop a more extensive root system that will “go deep” where the moisture level of the soil is higher. When you water amended soil, it holds water longer, making it available to the plant for long periods of time.
2. Use soaker hoses and drip irrigation. Watering directly at the root zone puts all the water into the soil. These types of watering systems slowly apply water to the plant so there’s no run-off and all the water goes directly to the plant. It takes much less water to keep the soil adequately moist and there’s less chance of disease problems since the foliage stays dry.
3. Always keep 2-3 inches of mulch in beds and around trees. It prevents moisture loss due to evaporation and keeps the soil cooler in the summer and warmer in the winter.
4. Always keep weeds pulled. Weeds compete with plants for water and they usually win!
5. During times of drought, do not fertilize unless absolutely necessary i.e.- nutrient deficiency, yellowing leaves, etc. Fertilizer containing nitrogen causes new, succulent growth that requires much more water. The more you fertilize with nitrogen, the more you must water to sustain the new growth of the plant. Do apply phosphate and potash. These elements improve the root system of the plant, increase drought-tolerance, and potash even acts as an “immune booster” by making plants less prone to stress from heat, dry soil, diseases, etc. Triple Super Phosphate and Triple Super Potash can be purchased at farm supply stores in 5 lb. bags. Read the label and don’t over-apply, they’re highly concentrated.
6. Fall and winter are the best times to plant because the plants won’t need much water to get established. Since the ground doesn’t freeze here in north Georgia, roots grow all winter long and have time to get well established before summer.
Watering the lawn- how much does it need?
Everyone must do their part to use water wisely and responsibly. Water conservation should always be practiced, even during times of adequate rainfall. On an annual basis, outdoor watering represents an average of 20% of the total water use in the home. During the summer, however, outdoor water use can represent up to 50% of the water used in the average home that has an automatic sprinkler system. Too often, the sprinkler system is run excessively at no added benefit to the lawn. Practice the following tips on proper water use and you'll probably be surprised at how good your yard will look with much less water than you might expect.
The lawn only needs 1" of water every 7-10 days, including rainfall. Place a few tuna cans in different areas of the lawn and time how long it takes the sprinkler system to fill them. Example: if it takes 1 hour to fill the cans, then set the system to run 30 minutes per zone one day, skip 4 days, then run it again for 30 minutes. On this schedule, the system only runs a total of 1 hour in an eight-day period yet the lawn receives all the water it needs to stay healthy and green. This method encourages the lawn to grow a deeper root system, and allows it to dry out between waterings. In addition to conserving water, this method reduces disease problems that must be treated with chemicals that are a result of frequent watering. Lawns prefer to dry out between waterings. Running the sprinkler system several times a week is wasteful and unnecessary. It also causes the lawn to grow a very shallow root system that cannot live without frequent watering. That means that when the state puts a total water ban into effect, this type of lawn is the first to die.
Always install a rain sensor to your automatic sprinkler system. They're inexpensive and will automatically keep the system from coming on during rain showers. There is much work being done on the technology of efficient watering systems, and one of the most promising is soil moisture meters. These are probes that are inserted into the soil and wired to the sprinkler systems control box. They tell the system when to come on based on the moisture in the soil instead of the amount of rain that has fallen. This is much more accurate than rain gauges because the system will not come on until the soil moisture reaches a pre-determined level that is set by the installer. The technology will get more user-friendly and economical with time but currently, any landscape professional that is experienced with irrigation system installation can add a soil monitor to your system.