In Colorado, most lawns are cool-season grasses. Kentucky Bluegrass is the most popular grass accounting for 95% of all turf areas. Tall Fescue is second and becoming more popular. The growing season for these grasses is April to October. A well designed and maintained automatic sprinkler system is recommended for Colorado lawns and to use water wisely. The following information applies to Kentucky Bluegrass, Tall Fescue, Fine Fescue, and Perennial Ryegrass.
Sun, shade, slope, wind, temperature, and season are all factors that determine how much to water your lawn and when. Watering uniformly, deeply and infrequently will keep your root system and yard healthy. Judgment and common sense are essential in determining when your grass needs water. It is vital to water your lawn if it dries out and becomes stressed. A deep-rooted healthy turf will withstand minor drought better than an over-watered yard. The following are signs your grass needs watering:
If any of these stages start to appear in your yard, it needs water. You can use a screwdriver to determine how much moisture is in your soil profile. If you can easily push a screwdriver into the lawn, you should have good soil moisture. If it is hard to push a screwdriver into the ground, your grass probably needs watering. Established yards need to be watered 3 to 4 times a week during times of extreme summer heat. A lawn growing in sandy soil will need to be watered more frequently with smaller amounts of water because sandy soils hold little plant-available moisture. Clay soils hold more water and require less frequent irrigation.
To determine how much water a sprinkler zone applies in one hour, place four identical rain gauges at various distances from a sprinkler head within its spray pattern. Run the sprinkler zone for 15 minutes. Pour all the water collected from the four gauges into one and measure with a ruler in inches. Let’s say the water collected from the four gages equals 1″. That means your sprinkler zone is putting on one 1″ of water per hour. Once you know how much water your sprinkler system applies in one hour, you can adjust sprinkler times based on how much water is needed each week for a given month. Please see the table on this page of water required per week for a given month. More about how to cup test your sprinkler system.
The most efficient time to water is late evening, after 9 p.m. and early morning before 5 a.m. It is less windy, cooler and more humid at this time of day, resulting in less evaporation and more efficient use of irrigation water. Water pressure is also better, and this results in optimal sprinkler distribution. Watering at night does not encourage disease development in Colorado due to the arid climate.
With most soils, do not apply all the water in one irrigation cycle. If water is applied too quickly, it will often run off turf areas due to slopes, compaction, heavy clay soils, and thatch. In these cases, it is more effective to apply half the water in two back to back irrigation cycles. Cycle and soak lawn watering allows the water to soak into the soil rather than runoff. Core cultivation, aeration can resolve some infiltration problems by reducing thatch and reducing compaction. More on cycle and soak lawn watering.
Mow cool-season grasses 1.5″ to 3″ tall when the turf is dry to the touch with a sharp blade. A dull mower blade will shred and fray grass blades instead of cutting them cleanly. The result is a brown, unattractive lawn and can promote disease. Mow no more than 1/3 of the grass height off during any mowing. If your mowing height is 2 inches, mow the grass when it is 3 inches tall. You may have to mow a good bluegrass or fescue lawn every three to four days during ideal growing conditions. If weather or other factors keep you from mowing your lawn, raise the height of cut to avoid cutting too much, or scalping your lawn. Mow the grass again two days later at the standard mowing height. Pick up the clippings if they form clumps and are matting down and smothering your lawn.
During routine mowing, let the grass clippings fall back onto the lawn. Grass clippings decompose quickly and provide a source of recycled nutrients and organic matter. Mulching mowers chop grass clipping into small pieces that fall into the lawn and get recycled. If you mow frequently, side-discharge rotary mowers also distribute clippings effectively. Grass clippings do not contribute to thatch accumulation.
To supply proper nutrition for your lawn, we suggest applying four applications of fertilizer per year. Fertilize in early spring, late spring, summer, and fall. How often and what type of fertilizer you use will determine the health of your lawn. If you are watering correctly, but your grass is thin, lighter green, or is not growing, you need to fertilize. We suggest applying a quick-release fertilizer when your lawn needs a boost. If your grass is thick and healthy, use a slow-release or organic fertilizer. Our Lawn Fertilizer Program.
Quick-release fertilizers green up your lawn quickly, promote top growth and root development. Slow-release fertilizers work slower and release nutrients over a more extended period. Organic fertilizers work even slower because the natural components must break down before the plant can utilize them. Use a fertilizer formulated for Colorado soils and our dry climate and stay away from national brands that are better suited for wetter climates. We have been selling fertilizers blended for Colorado for over 50 years. With a minimal amount of work, your lawn will look great and stay healthy. Our lawn fertilizers.