Excessive watering could 'kill your plants with kindness'

By G. Owen Yost

By far the most frequent question aimed at me is, "how much should I water my lawn?" Sorry, but there is no one-size-fits-all answer. I can only answer with the onslaught of words and observations that follow.

In kindergarten we were taught that every living thing needs water. So it's only human nature that we water plants a lot on these superheated days. But did you also know that far more plants are killed by overwatering than from not getting enough water? Basically, we DROWN plants quite often (even during droughts), due in part to our very human tendency to do what we were taught and also due to Denton's slow-draining soil.

If you're looking for strict rules about when and how much to water, remember that rules are made to be broken. In other words, all the rules about watering your yard take a back seat to this one; "water a plant when it needs it". Accompanying this simplistic and somewhat arrogant guideline is the guideline to water only the plant that needs water, not everything around it as well. For this reason I follow the central xeriscape guideline to group together plants with similar water requirements. Also, I prefer to use native Texas plants, instead of plants that are accustomed to other climates and soil. Natives love our environment just like it is!

Very generally (take this with a huge grain of salt) established plants in the summer can be watered once or twice a week ... any more and you risk harming them. (During the growing season I rarely water the established plants in my own landscape. A friend of mine, also a landscape architect, waters only about every two weeks). In the winter, believe it or not, all plants need monthly watering to keep the roots strong. Newly planted plants, however, need a lot of extra water, whatever the season, since they haven't grown roots yet, to get water from the soil.

When you water, especially on hot or windy days, it's far more effective to water in the early morning. A typical sprinkler used after about 10 a.m. loses much of its water output to evaporation, but you pay for it on your water bill anyway. In fact, watering in the afternoon and evening could result in leaf-scorch and fungus diseases. Lawns are particularly susceptible to fungus diseases if they're watered in the evening.

Since Denton's soil doesn't absorb water rapidly, it's best to slowly soak an area infrequently rather than spraying it heavily. The water should never run off - down the drain. Letting a hose barely dribble overnight on a plant every few weeks is far better than running a sprinkler for a long time. This kind of watering also encourages roots to grow deep down into the soil, so the plant resists drought more easily in the future.

As astounding as it sounds, plants can drown. They need to dry out between waterings and the roots need to make contact with the small air spaces within the soil (roots need contact with air to be able to grow). If water is always filling the air spaces, the plants simply die. So it's a smart idea to let the soil dry out completely before giving a plant more water..

While it may seem smart-alecky to say "water a plant only when it needs it," that's good advice. Learn to recognize the difference between how a landscape looks on a hot day and one that actually needs watering. For example, drooping leaves may not mean that a plant needs water. Also, learn the other signals of a truly thirsty plant. Then you won't run the risk of unknowingly killing your plants with kindness.

Owen Yost is an area landscape architect specializing in designing low-maintenance landscapes while incorporating native plants with hardscape. He is a member of the American Society of Landscape Architects, Keep Denton Beautiful and the Native Plant Society of Texas. His Denton office is at 4516 Coyote Point; call 940-382-2099 or 940-383-9655 or e-mail him at Yost87@charter.net