Keys to Proper Landscape and Garden Watering

by Dr. Douglas F. Welsh, Landscape Horticulturist
Texas A&M University

In a few months we will be in the midst of another hot Texas summer. Properly watering plants during the summer tends to be one of the most confusing and misunderstood gardening chores. Often, ardent gardeners do not recognize inadequate watering until it is too late and plants are badly damaged or dead.

“How often should I water?” and “How much should I apply?” are a couple of the most-often asked questions from gardeners. Since water is both essential for healthy plant growth and often costly to apply in quantity during the summer, it is important to get it to the plant’s roots efficiently and keep it there.

The following are several suggestions for easier and more effective watering. These techniques apply to all gardening, from shade and fruit trees and vegetable gardens to lawns and house plants.

1. Never water strictly by the calendar. We don’t drink water 'every ten minutes' or 'every hour', so why should plants be watered 'every two days' or 'once a week'? Instead, learn to recognize dry plants and soil and use these as your tip-off for watering. Too many factors determine how fast a soil dries for us to put watering on a regular basis.

2. When the plants are dry, water thoroughly. Water lawns so that the soil will be wet several inches down, to encourage deep rooting and drought tolerance. One of the worst mistakes people make in their gardens is trying to 'sprinkle' them each day by using their thumb and the end of a running hose. Most gardeners just don’t have the patience to stand in one spot long enough for deep water penetration.

   Water trees by taking the sprinkler off the end of the hose and letting water run slowly for several hours out under the drip line (not near the trunk). Be sure that runoff does not occur.

3. Most plants should be watered in the morning. Evening watering increases the likelihood of disease invasion, as the majority of diseases develop most rapidly in cool, moist conditions.

4. While watering your lawn, try to keep water off the leaves of trees and shrubs as much as possible. This is especially important for such plants as crape myrtle and roses, which are troubled by leaf diseases which spread rapidly on wet surfaces.

5. Symptoms for plants which have been kept too wet are about the same as for those kept too dry. Roots in waterlogged soils die and do not take up water, so plants wilt and turn yellow. Try not to water a drowning plant!

6. Organic matter, such as shredded pine bark and composted manure can increase water absorption when they are worked into our native soil.

   To keep moisture in the soil, use a thick mulch, such as shredded pine bark, grass clippings or tree leaves. In addition to reducing evaporation, mulches also keep the soil cooler and make weed pulling much easier.

7. Be especially careful to keep newly planted trees and shrubs well watered. Their developing root systems are sensitive to under- and over-watering. But again, don’t drown them.

8. Always soak chemical fertilizers into the soil immediately after application. These materials are excellent sources of plant foods, but they are also salts, and can pull water out of plant tissues, resulting in burn, unless they are watered into the soil.

9. Gardeners often wonder what type of sprinkler is best. Generally speaking, most do a satisfactory job of making an even application. However the most efficient and effective type is the impact sprinkler (the kind used on golf courses and athletic fields).

For plants to thrive during the upcoming summer months, they will need plenty of water, but equally important is properly applying the much needed water.