Best Management Practices Important In Landscape Irrigation Says LSU AgCenter Horticulturist

Allen D. Owings  |  5/27/2005 1:46:07 AM

Marigolds fit into a Best Management Practices landscape plan, because they don’t require much water during a normal hot, dry summer. With a drought threatening, the flowers are especially worth serious consideration.

News You Can Use For June 2005

If our dry spring months extend into the summer, we will need to remember some important considerations when watering home landscapes, according to LSU AgCenter horticulturist Dr. Allen Owings.

The proper irrigation techniques for improved application and efficiency are known as best management practices.

"Quite possibly the most critical BMP in any landscape planting is water, yet it is often one of the most difficult to determine," Owings remarks. Newly set shrubs should be watered at least once per week during dry weather.

Water thoroughly and deeply to promote deep root penetration. Shallow watering keeps root systems near the surface. Shallow root systems subject the plant to damage from heat and drought. Once plants have become established, they can go for longer periods without water. It is good practice to water beds thoroughly once a week during hot, dry weather.

For annual and perennial flowers, irrigation requirements vary. Avoid overwatering. When normal rainfall does not provide adequate moisture (about 1/2 inch to 1 inch per week), supplemental water will be needed. A thorough soaking is preferred instead of frequent sprinklings.

Home landscapes account for a small but significant amount of water usage in Louisiana landscapes. Careful management can improve the performance of plants and still conserve water.

Owings makes the following recommendations to help reduce water usage.

• Keep the size manageable. A small, flower garden provides more enjoyment than a large, weedy, poorly maintained planting. Don't feel guilty for not providing everyone in the neighborhood vegetables all summer long.

• Add organic matter to the soil. Organic matter such as compost, cow manure, rotted sawdust or hay or peat moss improves soil when it does rain. Once in the soil, organic matter acts like a sponge, holding water in the root zone where the plants can use it.

• Use a mulch. Mulching reduces water demand by as much as 40 percent. Mulches keep the soil cooler, eliminate weed competition and reduce evaporation from the soil surface. Eye appeal is an important consideration for flower garden mulches, whereas efficiency and ready availability are more important in the vegetable garden.

Good mulches for flower gardens include pine bark, shredded hardwood bard, pine needles and cottonseed hulls. These should be applied at least 2 inches deep for maximum benefit. Black plastic has become popular as a vegetable garden mulch. It is especially beneficial when used with drip irrigation.

Good organic mulches for the vegetable garden include old hay, rotted straw or leaves. Dry lawn clippings also make a good mulch, but they usually are best left on the lawn where they fall.

• Space plants farther apart. Crowding plants close together results in intense competition for water. In the flower garden, space annual plants at least 12 inches apart, and space perennials at least 18 to 24 inches apart. In the vegetable garden, use wide row spacing and give the plants more room in the row. Plants should be thinned to have only one plant per hill.

• Control the weeds. Weeds, especially grasses such as crabgrass, are extremely aggressive competitors for water. Keep them under control by mulching or by hand cultivation. Use drip irrigation or soaker hoses to water. These apply water slowly, directly to the soil. This helps ensure that the plants get all of the water. Also, because the foliage stays dry, the incidence of leaf disease is reduced.

Grow plants that avoid the drought. Many flower garden plants have a sufficiently fast growth cycle so that they "do their thing" before the heat of summer arrives. Flowers such as tulips, daffodils, pansies, irises, poppies and columbines complete their life cycle before the heat of summer arrives.

In the summer, grow drought-tolerant plants. Many plants have excellent drought tolerance. Flowers such as lantana, purslane, portulaca, periwinkle and marigolds have excellent drought tolerance. A host of native wildflowers such as purple coneflower, black-eyed Susan, butterfly weed and verbena provide color in the driest years.

For related topics, look for Gardening and Get It Growing links at the LSU AgCenter Web site, Additional yard and garden topics are available from an extension agent in your parish LSU AgCenter office.


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