Lawn Irrigation – Watering Basics

Lawn irrigation is probably the trickiest of lawn maintenance tasks. “How much water is enough?” is a persistent and nagging question. There is, unfortunately, no simple answer. Grass variety, soil, weather, and cultural practices all play a role in determining what part a lawn irrigation schedule plays in a lawn maintenance program.

A lawn irrigation plan that works for cool-season grass lawns in northeast America will not work well for west coast lawns. Tropical and subtropical lawns such as those in Florida and Louisiana need strategies different from those demanded for arid and desert conditions.

This article describes simple requirements necessary to include lawn irrigation and watering basics in a lawn maintenance program.

July is Smart Irrigation Month

The Irrigation Association (Falls Church, VA) designated July as Smart Irrigation Month because this is a peak time for lawn irrigation. The Irrigation Association is a professional group that raises awareness of:

• Ecologically sensitive lawn and garden irrigation
• Innovative irrigation products and practices, and
• Water conservation.

Beth Casteel, communications manager for the Irrigation Association, says “The key to efficient outdoor irrigation is applying just enough water and only when necessary. Water-wise habits will result in a healthier lawn and landscape, in addition to conserving water. Plus, reducing your consumption will help reduce your water bill.”

Basic Lawn Irrigation Strategy

On average, most grasses need about one to two inches of water per week to maintain

• Green color
• Active growth, and
• Healthy vigor.

Home landscape gardeners can begin to work out a lawn irrigation schedule by starting with that recommendation. They can then go on to develop a system adapted for their own needs.

Here is a simple way to measure the total time necessary to put down one to two inches of water on a lawn. It does not matter whether lawn irrigation takes place with above ground hoses and mechanical sprinklers, or automated irrigation systems regulated by timers.

• Set out equally sized containers (coffee cans or something similar) evenly around the lawn. This is also a fine way to check an irrigation system’s pattern and rate of distribution.
• Adjust the water flow through the sprinkler(s) at a normal pressure and flow rate.
• Measure the amount of time it takes to accumulate the desired amount of water in each can.

The amount of time it takes to accumulate one to two inches of water per container should be about the same. However, just about all sprinklers and sprinkler heads need some adjustment. Watering patterns should overlap so that no one spot receives too little or too much water.

Lawn Irrigation Requirements for Specific Lawn Types

Grass varieties vary from those with high water requirements to those which perform well with little water. Homeowners with springs or wells, or those whose communities consistently enforce sprinkling bans, should choose grasses with low water requirements. Here are some examples:

• Cool-season grasses (grow well in northern regions of North America): Bluegrass has the highest water requirements; Perennial ryegrass, medium requirements; Fairway wheat and Fescue grasses, the lowest.
• Warm-season grasses (grow in southern regions): Grass varieties suitable for lawns in the south have low to medium water requirements. Bahia, Centipede, Seashore paspalum, and Zoysia grasses have the lowest water requirements; Bermuda, St. Augustine, and Carpet grass, medium requirements.
• Transition-area grasses (North American natives that grow well in either northern or southern regions): Bluestem and Buffalo grasses both have medium water requirements.

The turf grass industry introduces almost annually new “improved cultivars” for each kind or variety of grass. Homeowners preparing to install a new lawn should investigate recently introduced cultivars and choose the best for each unique situation.