Garden plants need water, and if nature doesn't supply it in the form of gentle, soaking rains then gardeners will need to do so. However, according to the National Weather Service much of the United States is in a current state of drought, with continued dry conditions expected. And homeowners who rely on municipal water supplies are seeing costs rise dramatically. So it just makes sense to conserve water and use this precious resource wisely.
How can gardeners maintain healthy plants while minimizing water usage? We've all seen sprinklers running on a rainy day, or a misdirected stream of water saturating pavement instead of plants. These obvious wastes of water are the first to remedy. But there are many more was to conserve. Here are some watering basics.
Above-ground sprinklers are popular for covering large areas, such as lawns. They are easy to use and can be moved around to cover all areas of the yard. Drip irrigation systems allow you to situate emitters so they apply water to the soil around plants, making them excellent for conserving water. Likewise, soaker hoses allow water to seep slowly into garden beds. Unless you are very patient, your yard is very small, or you are watering container plants, hand-watering is less than ideal. You'd be surprised at how long it takes to apply enough water to soak plants' root zones!
You may be surprised at how much water is lost to evaporation when you water on a warm, sunny afternoon -- estimates put the amount at up to 30%. The best time to water is early morning or evening because much less water will be lost to evaporation than when you water in the midday heat.. If you are using an overhead sprinkler water in the morning so foliage can dry quickly, minimizing disease problems, such as black spot on roses, that thrive on moist leaves. During drought conditions, some municipalities mandate that watering be done after dark. A programmable timer that turns water on and off at set times is especially handy in this situation.
Most plants prefer a thorough soaking followed by a period where the soil is allowed to dry out a bit. By watering infrequently, but thoroughly, you'll encourage plants to develop strong, deep root systems. A daily light sprinkle, on the other hand, causes plants to develop shallow surface roots that are prone to drying out if their daily water fix is missed.
Water slowly for best results; think of a gentle summer rain that lasts for several hours. Water applied slowly will seep into the soil where it can be used by plant roots. Water applied with a heavy hand, or during a downpour, often runs off rather than soaking in. This is not only a waste of water, but can also lead to pollution problems if fertilizer is contained in the runoff and finds its way to a lake or stream. Soaker hoses minimize runoff, but there are other ways to help, too. For example, create a "donut" of soil around new plants by mounding soil into a low, circular berm several inches from the stem or trunk. This creates a shallow bowl where the water you apply will puddle and soak in slowly, rather than running off. Once plants are established, flatten this berm so water drains away from the plant. If necessary, install a pressure regulator to lower the flow rate of sprinklers or soaker hoses so water is applied slowly and gently.
Both the frequency and amount of water required will vary with your climate, soil, and plants' needs. Shallow-rooted annual flowers need more frequent, lighter waterings than deep-rooted trees. Heavy clay soil retains water better than sandy soil. The best way to determine how much water to apply, and how frequently to apply it, is to use a shovel. After watering, use the shovel to remove a wedge of soil in the garden or lawn. The soil should be moist to a depth of at least six inches for annual plants, and 12 inches for perennials, shrubs, and trees. Most of the roots plants use to take up water are located in these zones. (Don't forget to replace the wedge of soil.)
A timer is useful to turn on and off your sprinker. You can then begin keeping records of how long it takes to moisten the soil to the desired depth and set the timer accordingly. For example, a weekly two-hour watering might be just right for your perennial bed or lawn, while your annual planting may need just 15 minutes.
Between waterings, use your shovel again to determine when to water again. Remove a wedge of soil; if it's dry three inches down for annuals, or six inches for larger plants, it's probably time to water again, unless a soaking rain is predicted.
Interestingly, adding organic matter to soil helps it absorb and retain water, while also improving its drainage. Mix in organic matter at planting time and use organic mulches, such as bark chips or pine straw; as they decompose they'll add organic matter to soil.
Water is vital to plants, but taking time out of a busy day to water the garden can be difficult. Set up a system that makes it easy for you. For example, run separate hoses to different parts of the garden, so you don't have to lug them around. Set up a soaker hose or sprinkler on an automated timer. Attach quick-release hose connectors and shut-off valves to avoid trips back to the tap. Use a watering wand that can be adjusted to apply a gentle shower to plants and a stronger stream to hose off containers. Use self-watering containers to prolong the time between waterings. Use a decorative hose reel, bowl, or holder so you can store your hoses close to your gardens.