Ken Brennen, Extension Master Gardener in Anoka County, April, 2014
Thinking spring often means thinking about a lush spring lawn. Here are some tips for getting the typical Anoka County lawn off to a good start. But temper your enthusiasm. Don't work on your lawn while it is wet or you'll do more damage than good.
Most of our lawns are cool season Kentucky Bluegrass mixes that grow with spring and fall moisture and are dormant in warm dry summer weather. The best times to fertilize are during these growth periods. In the spring it is from mid-May to mid-June. Either a drop or rotary spreader will do. The most essential nutrient for grass is nitrogen, but look for a fertilizer labeled "slow release" nitrogen. Other types will give a quickly fading burst of green while adding to the earth's nitrogen pollution and may leave ugly burn spots in your grass.
Nitrogen is only a fraction of the weight of any fertilizer. Lawn spreaders are calibrated to give 2 pounds of nitrogen per 1000 square feet. Check the back of the fertilizer bag for the recommended setting for your brand of spreader. Less is better than more because excess nitrogen can cause your grass plants to grow so fast they become scrawny and susceptible to a variety of lawn diseases.
Your lawn mower is your most important lawn maintenance tool. It can help you reduce water usage, fertilize the lawn, and prevent the growth of annual weeds. Keep it sharp so it cuts, rather than tears the grass. Set your mower height to two inches, then let your grass grow to about three inches before mowing. Longer grass shades the roots reducing the need for additional water. A secondary benefit of shading the roots is it prevents the growth of annual weed seeds which require sunlight to sprout, so your lawnmower can act like a pre-emergent weed killer.
Your mower will also help you fertilize your lawn by recycling that nitrogen you worked so hard to apply. Just let the clippings fall back on the lawn. They will quickly decompose, releasing their nitrogen back to the soil. Some folks worry about forming lawn-choking "thatch" from clippings, but lawn experts tell us thatch forms from the tough stems lower on the plant, not the leaf clippings.
As dry summer weather comes on you will have to water your lawn. The recommended rate is one inch per week preferably applied in two equal applications. Water in the morning so that the grass has a chance to dry quickly and lessen the chance of disease. To determine how much water you've applied place a flat container like a tuna fish cane on the lawn and check the depth. Much more lawn information is available at: http://www.extension.umn.edu/garden/yard-garden/lawns/ .