The Art of Watering

Help your plants survive and thrive in even the most severe dry spells.
Linda Askey

How dry was it the summer before last? In some parts of the South, the drought of 2000 was so extreme people called to tell us their weeds were dying. Although fall rains brought relief, much damage had already been done. Many homeowners watched helplessly as their precious landscapes withered.

"I like to use the analogy that roots are like sponges," says retired Extension agent George Stritikus. "When an old sponge dries out dramatically, it won't take up water anymore. That's why I always say to keep roots covered with mulch." George preaches the benefits of placing a 4-inch layer of mulch around your trees and shrubs. Without this protective layer, heat and winds steal water from plants. "There is a point called permanent wilt, beyond which there is nothing you can do," he says. "The plant's not dead yet, but it can't absorb water. That's what you want to avoid in the landscape."

For turf, perennials, shrubs, and trees, it's always the new plantings that are most susceptible to droughts. The next hardest hit are understory plantings that have to compete for water with the roots of larger trees. According to George, evergreen understory plants, such as azaleas, had the most difficult time coping with the drought. Because evergreens hold their leaves through the winter, they need periodic deep watering all year long, or they might experience permanent wilt.

Frequent, shallow waterings lead to plants that develop shallow roots in the top 1 or 2 inches of the soil, where they find moisture. When you go away for a week, the surface of the soil dries out quickly and your plants suffer. How much to water depends on the size of the plant. But water deeply, and then wait until plants are thirsty (not parched) before soaking the soil again.

When an evergreen turns brown and drops its leaves or needles, it's time to get a replacement. With deciduous trees and shrubs, however, it can be trickier to predict whether they lost their leaves due to the natural defoliation that comes with fall--or whether it was the throes of a death scene.

"During a bad drought, the leaves on deciduous plants will simply turn brown and fall," George explains. "That's natural, and I tell people to just wait and see if it comes back in spring.

If your plants are in fact ready for the compost heap, the sooner in the spring you can get around to replacing them, the better the chances are that new plants will make it through whatever problems await in the summer."

Lawns are a different story. In times of drought, they're actually more resilient than you might think. Although they look dead, they may just be dormant. Call an Extension agent if you aren't sure you can tell the difference.

Sprinklers, Soakers, and Drips

You need to select the right method of applying water. Because every situation is different, you might need different models to fit various niches.

  • Sprinklers simulate rain, except that sprinkler heads often throw the water horizontally. This means you need to watch out for rain shadows, which are dry areas caused by trees, shrubs, and other obstacles that block the water spray. Sprinklers are the best method for watering turf and large areas of ground covers. Set sprinkler heads at different angles and with generous overlaps to make sure all areas are covered.
  • Soaker hoses 'sweat' water and are generally made of recycled tires. When covered by a layer of mulch, such hoses lose very little water to evaporation. They are ideal for rows of vegetables or long, narrow beds, but they won't work for an expanse of lawn. They are also good on steep slopes, where sprinkler sprays might lead to runoff and erosion.
  • Drip irrigation systems deliver water very economically. As with soaker hoses, they can be covered with mulch to minimize evaporation or runoff. They are perfect for roses and other plants that have problems with black spot, mildew, and other diseases caused by water on the foliage. They can be used anywhere you have individual plants, from cabbages to oak trees. They also work for containers and even hanging baskets.