Lawn and Garden Irrigation
What is the best way to irrigate my lawn and garden? I see my neighbor’s sprinklers go on at 6 am every morning for 10 minute intervals when I take my walk. Is that the best method for irrigation?
Night time or early morning is the best time to irrigate because water evaporation is lowest and less water is wasted. Water pressure is also usually higher that time of day. However, I do not recommend daily irrigation.
The best method is to apply enough water to wet the soil to the depth of the root system and then let the soil dry out on top between irrigations. 10 minutes is seldom long enough to wet the soil to the 4 to 6 inch depth of lawns, flowers and vegetables. It normally takes about ½ inch of water to reach that depth. You can check how long it takes for your system to apply that much water by placing shallow cans like tuna fish cans at various locations. Check each of the different kinds of sprinkler heads in your system. Spray heads put out water much faster than rotating heads. When you have determined how long it takes to accumulate a half inch of water in a can, you know how long to let each set of sprinklers run.
A three or four day interval may be adequate in early June. It may require a 2 day interval in July and August.
This can approach is a good way to check for dry or wet spots. Sprinkler heads may need to be adjusted or an additional head added.
Another reason to avoid daily irrigation is because it encourages weed seed germination. There are always weed seeds in the top of the soil. Constant moisture encourages them to sprout.
Sunny, south or west facing areas dry out faster than shady, north or east facing areas. If your irrigation system is set up so you can give extra time to south and west facing areas, the plants will benefit from the extra water.
The ideal irrigation system has different zones for lawn and shrubs. Trees and shrubs have deeper roots than lawns. They benefit from deeper irrigation at less frequent intervals.
Newly planted plants require more frequent irrigation until their roots are established. Daily irrigation may be needed for the first week or two.
Allen Wilson
Allen has been writing about gardening for over 30 years. He is a retired professor of Horticulture.