I see the first true sign that spring has arrived - dandelions in bloom! Which means the lawn maintenance season has just begun. Maintaining a lawn requires three essential ingredients: proper watering, mowing and fertility. This week: Watering.
To maintain a lush, green appearance, conventional lawns need a minimum of 2.5 cm (1 in.) of water per week in spring and fall and up to 4 cm (1.5 in.) during the heat of summer. Whatever doesn't fall from the sky as rainfall, you need to supply through irrigation. You can measure the amount of water as you irrigate with either a rain gauge set on the ground or a plastic container with depth measurements marked on the side.
Avoid using sprinklers that create a fine mist or throw water high in the air (like the ones children like to run through). Much of the water from both of these will evaporate before it hits the ground. What you want are large water droplets applied close to the ground.
Delay watering your lawn until the top several centimetres (few inches) of soil moisture from spring snow melt has dried out. During the growing season, water only when the soil surface has begun to dry out. After each watering, the soil should be moist to a depth of 20 centimetres (8 in.) or more. Ideally this will be several centimetres (a few inches) below the root zone of the lawn.
Deep root development is one of the major factors that contribute to drought tolerance regardless of grass species. Deep roots are encouraged with deep and thorough soil preparation and deep, infrequent watering. Plants initially absorb water near the soil surface and then at progressively greater depths as water percolates down into the soil. Watering deeply but less frequently also discourages warm-season weeds and annual bluegrass, both of which thrive on frequent shallow irrigation.
If you have a large lawn, separate it into irrigation zones according to water needs. Shaded areas of lawn require less water than ones in full sun or adjacent to large masses of cement or reflective siding. Lawns with heavy use and associated wear or those competing with the root systems of trees also require extra water. As do lawns on slopes or banks, especially those with a south- or west-facing exposure. On slopes, irrigation may have to be interrupted (e.g. repeated cycles of 15 minutes on followed by 30 minutes off until you've applied enough water) to prevent runoff.
Irrigation systems may apply water at a faster rate than can be absorbed into the soil. The result is runoff onto sidewalks and streets is wasted water. Time the irrigation cycle so that what is applied can be absorbed. Heavier clay soils require an interrupted schedule as above for sloped lawns. Water during the coolest time of the day when winds are calm, usually in the early morning before 7 a.m.
Excessive watering after applying fertilizer may cause it to leach below the root zone of the grass where it does little good and may end up contaminating the water table. Depending on soil type, only 10 mm (1/2 in.) or less of water is needed to bring these products into the root zone where they will be used.
Lawn grasses are "colour coded" to indicate drought-stress, turning from a bright or dark green to blue grey in the initial stages. "Foot printing" and colour change indicate a need for water. Water before these signs are evident. Otherwise, your lawn may become stunted, brown and enter a dormant state until fall rains revive it. Allowing your lawn to experience drought conditions can lead to thinning, patchiness and weed infestations.
Next week: Mowing and Fertilizer.
- Sara Williams is the author of the revised and updated Creating the Prairie Xeriscape, Coteau Books, February, 2013. This column is provided courtesy of the Saskatchewan Perennial Society (www.saskperennial.ca; email: [email protected]).
