In winter, grass and plants are not actively growing. But winter weeds like dandelions and henbit are multiplying with every drop of water they get.
A quick show of hands please: who has been running the irrigation system at least once a week during winter? Now ask yourself why — because dormant grass doesn’t grow.
As long as soil temperatures are below 70 degrees, turf grasses will not produce green shoots. Only the roots of grasses, trees and shrubs are active in the winter. What will turn green are the germinating winter weeds like dandelions and henbit, along with cool-season weedy grasses such as rye, fescue, Poa annua and rescue grass.
Normally, a good winter recommendation is to apply ½ inch of water to the landscape every four weeks since the grass and plants are not actively growing. However, a rainfall of ½ inch or more is enough to delay irrigation for at least four weeks in winter.
Soil depth is very important in the water needs of plants and grass for winter. Soil at least six inches deep or more will hold moisture longer, requiring less frequent irrigation or rainfall. Landscapes with soil less than six inches deep may require some kind of irrigation or rainfall at least once every two weeks.
Shrubs and trees require less water than grasses in winter and usually do well on rainfall alone. If water is needed, use a hand-held hose to apply water to individual shrubs and trees once or twice during the winter and use irrigation sparingly on grasses.
While most winters in San Antonio are mild, they are still cool enough to keep warm season grasses (St. Augustine, Bermuda, zoysia, buffalo) from growing and remaining emerald green.
These grasses do not need lots of water to survive the winter. Using extra water outdoors in the winter does nothing but make your sewer bill grow for the following year. Next time you’re in the garage, stop by the irrigation controller and switch it to off or manual until after March 15.