Q. With watering restrictions almost a certainty, is there a proper way to prepare your lawn to go dormant or for a reduced watering schedule so the lawn will come back next year healthy. Steve Ostrander -Graham, WA
A. As far as restrictions being a “certainty” please reference the article this past Tuesday in the News Tribune “Water supply should last through summer” by Susan Gordon. Whether or not we have water restrictions many people still wish to conserve water. The summer lawn is often a large percentage of most homeowners’ water bill. Summer dormancy is a condition cool season lawn grasses are genetically programmed for. The simple answer is: if you have a healthy lawn it will be prepared for summer dormancy. So for example if you have weed problems they will be exacerbated by the dormancy period. This is because the advantage most weeds have is that they do not go dormant in heat and drought the way lawn grasses do. Weeds usually have deeper roots like tap roots and other water gathering strategies. In addition many weeds use a different biochemical pathway to absorb carbon dioxide from the atmosphere. Carbon dioxide is a necessary component of the production of sugar in photosynthesis. The weed’s pathway is a much more efficient pathway than the one the cool weather grasses’ at absorbing carbon dioxide. This means the pores of the plants (called stomates) do not need to stay open as long to gather carbon dioxide. When the pores are open the plant loses water through evapotranspiration. So weeds loose less moisture in hot/dry weather and thus their advantage. Thatch is another important element in summer lawn water conservation. A ½ inch thatch layer is healthy and normal and will serve to keep the soil below the lawn from allowing moisture to evaporate. Using a mulching mower to send the grass clippings back into the lawn is also helpful in reducing water usage since it serves as a mulch. Also keep your lawn length high as we approach the summer – around 2-½ inches. Fertilize the lawn in the spring with a slow release fertilizer but do not fertilize in the summer. This is especially important if you use inorganic fertilizers. These fertilizers are salt based and can draw moisture away from the roots if they remain in the soil unused.