News Release Distributed 04/15/11

By LSU AgCenter Horticulturists Dan Gill, Kyle Huffstickler and Allen Owings

Who knows how much rain we’ll get during spring and summer? We need to keep in mind that many areas of Louisiana are experiencing below-average rainfall amounts. And it’s common to get significant rain events followed by three to four weeks of dry weather. How do we irrigate our landscapes under these conditions? This is a question that comes up often and is sometimes hard to answer.

“How much water do I need to apply?” and “How often do I need to water this plant?” are common questions from many home gardeners. Water is essential for healthy plant growth, but it can be costly to apply, depending on your water source. Remember, it’s important to get water to plant roots efficiently and effectively and keep the moisture in the root zone.

Too many gardeners have a tendency to water by using the calendar. Once a week or twice a week is a common practice. Some people even water plants daily.

Gardeners need to learn how to recognize drought stress in plants. You do this by monitoring soil conditions in containers and landscape beds. When one plant in a bed needs water, however, all plants in the bed may not need irrigating. Many factors determine how fast a particular soil or potting medium will dry out.

When plants are dry, water them thoroughly.

For lawns, water at a rate so that the moisture penetrates the soil to a depth of several inches. This encourages deeper root growth and also aids the plants in being able to handle droughty conditions that may come later in the year.

Try to eliminate the desire to “sprinkle” a lawn or landscape bed for a few minutes every day. This is not very helpful and actually discourages the plant from being able to withstand dry conditions later.

Gardeners often wonder what kind of sprinklers to use on their lawn or what kind of hose or sprinklers to use in their landscape beds.

For lawns, an efficient type of sprinkler is called an impact sprinkler. These are commonly seen on athletic fields and golf courses.

In landscape beds, use short-length soaker hoses, or use a micro-irrigation drip system that has individual emitters on shrubs and roses. For bedding-plant areas, you may use spray stakes off a micro-irrigation system, but be sure to direct the water underneath the foliage or downward toward the mulch or soil.

Irrigate trees by running a hose very slowly for a couple of hours. The hose should be placed within the tree drip line of mature trees or at the edge of the planting hole for newly planted trees. Do not let excess water run off.

The best time to irrigate plants is during the early morning. Avoid wetting the leaves – this encourages disease. Roses and bedding plants are most susceptible to problems with water accumulation on flowers and foliage.

Organic matter in landscape beds helps to maintain soil moisture. Apply mulch in all landscape beds twice a year. Pine straw and pine bark are excellent mulches. You can use hardwood mulch around many trees. Mulch flowers to a depth of 1-2 inches, shrubs to a depth of 2-3 inches and trees to a depth of 3-4 inches.

Irrigation is an important consideration in home landscapes. By following these hints, you can help your plants through droughty periods so they’ll be more productive for you.

Visit LaHouse in Baton Rouge to see sustainable landscape practices in action. The home and landscape resource center is near the intersection of Burbank Drive and Nicholson Drive (Louisiana Highway 30) in Baton Rouge, across the street from the LSU baseball stadium. For more information, go to www.lsuagcenter.com/lahouse and www.lsuagcenter.com/lyn.