As virtually all Minnesota lawns use cool season turf grasses, proper maintenance is required to ensure long-term health. Proper maintenance typically includes watering, mowing, and fertilization.
A variety of cool season grasses are used in Minnesota, with common types of Kentucky bluegrasses and fine-leaved fescues leading the way. Less used varieties include perennial ryegrass and the newer types of Kentucky bluegrass. Maintenance requirements can vary somewhat depending on what type of grass you have in your lawn. For example, ryegrasses tend to have somewhat greater water requirements than the relatively drought-tolerant common bluegrasses. However, no matter what type of grass you are using in your Minnesota lawn, the essential requirements remain the same.
In average-weather years, the Minnesota climate provides sufficient water to maintain a healthy lawn through most months. According to the University of Minnesota, the Minneapolis/St. Paul area receives more than enough rainfall, on average, during the spring and fall growing season. During the summer months from June to September, however, some supplemental watering is required.
Minnesota lawns use an average of four to six inches of water each month during the summer. To determine supplemental watering requirements, you need only subtract the actual rainfall from the monthly total and make up the rest through irrigation. This, of course, need not be an exact science. It is an excellent rule of thumb, however. For example, if your city receives 2 inches of rain during an average July, you should plan to water your lawn about an inch every week, subject to adjustment as the weather changes.
There are several important mowing tips that improve the health and vigor of any lawn, whether in Minnesota or elsewhere. First, periodically sharpen your lawn mower’s blade. A dull blade shreds the grass leaves, requiring your lawn to expend important energy in repairing that damage and increasing its water usage. Additionally, damaged grass leaves are more susceptible to diseases.
Next, mow your grass high and mow it frequently. Taller lawns have deeper roots. And deeply rooted lawns are healthier lawns. Additionally, taller lawns allow less sunlight through to the underlying soil, reducing water evaporation and prohibiting the growth of light-hungry weeds. Lastly, frequent mowing allows you to leave grass clippings on the lawn, rather than bagging them for disposal. Clippings less than an inch long quickly fall to the soil level where they decompose.
To maintain your lawn’s vigor and its resistance to diseases, pests, and weeds, it requires a yearly application of N-P-K fertilizer. The amount of fertilizer your lawn requires depends on the current fertility of the soil underlying your lawn. The University of Minnesota operates a soil testing laboratory that accepts soil submissions from any homeowner. The tests are inexpensive and the laboratory will provide you with detailed fertilization recommendations.
A healthy, well-maintained lawn is the single best defense against weeds. In many cases, weed management in a healthy lawn is simply a matter of pulling a weed here and there every once in a while. However, in cases where weeds are growing fast and thick, an herbicide may be necessary. Herbicides are available that target most common lawn weeds.