The new generation in landscape watering is here. Drip irrigation is the highly efficient delivery of water to plants near their base through flexible polyethylene (poly) tubing fitted with water-dripping devices (emitters) and low-volume micro-sprays. By slowly delivering water exactly where water is needed, drip irrigation minimizes overspray, nearly eliminates evaporation and reduces runoff. All this adds up to dramatically reduced landscape water use.
In addition to water savings, incorporating a drip irrigation system into landscaping has many other benefits, such as encouraging healthier plants. Drip irrigation maintains near-perfect moisture levels in the root zone of plants, enabling them to develop deep roots that are more resistant to dry spells. Eliminating overwatering also helps prevent plant disease and minimizes weed growth.
Drip systems are also flexible and scalable. They’re controlled by hand or by an automatic timer and can effectively irrigate all types of landscape: shrubs, trees, perennial beds, ground covers, annuals and lawns. A drip system can be used to irrigate new landscaping as well as to retrofit an existing traditional sprinkler system. And once a drip system is installed, poly tubing, emitters and micro-sprays can easily be added or removed to accommodate a change in the landscaping layout.
Most drip systems can be installed without special knowledge or tools and require no trenching. The poly tubing is laid out on the ground and covered with mulch or gravel to water trees, shrubs, annual and perennial beds, and ground covers. For drip systems used for lawn irrigation, however, 4- to 6-inch trenches are required for placement of emitter lines. Trenches can be dug by hand, with a mechanical trencher or by other means. If practical, the poly tubing for the lawn can be laid before the final four inches of soil is spread in the lawn area.
Planning and Installation Tips
- Don't skimp on the number of emitters. The goal when using emitters is to water the plant's entire root system. Large trees can require 12 to 36 emitters or more, while small shrubs may need only two or three emitters. Use a minimum of two emitters per plant in case one emitter clogs.
- Space emitters evenly around plants, staying at least six inches from the base of the plant to prevent fungal infections on the main stem. For plants located on a hillside, place the majority of the emitters on the upper side of the plant, allowing water to drip to the lower side.
- Use zoning. During the landscape design, plan to group similar plants together—i.e., separate dry-climate plants from humid-climate plants, separate trees from shrubs, etc. This will enable you to set up watering zones with watering frequencies best-suited for each type of plant. Large landscapes that contain various soil types can be separated by zones too.
- To prevent the small orifices of the drippers and micro-sprinklers from clogging, install a filter at the beginning of the system. Typically, a screen mesh of 150 is recommended, although the water quality and the type of emitters used could dictate that a different mesh be used.
- Install a pressure regulator. A regulator will maintain a constant pressure throughout the system, ideally between 10 and 30 pounds per square inch. Systems with too high, too low or inconsistent pressure won't operate correctly and can leak.
- To develop correct watering schedules, pay attention to your plants and adjust the watering to meet their needs. For example, run the system a little longer in hot weather and shorten the run times during cooler weather.