Did you hear about the guy who got rid of his old lawnmower? It just didn’t cut it.

In addition to a good lawnmower, a healthy lawn depends on the right timing of tasks such as fertilizing, watering, and weed control. When is just as important as how.

Our lawns in the upper Midwest are made up of species known as cool season grasses because they grow fastest in spring and fall, when temperatures are cool and moisture is usually plentiful. These grasses, including Kentucky bluegrass and fescue, become less active during the heat and drought of midsummer, and even turn brown and dormant if the hot, dry conditions persist.

Although our grasses slow down a bit in midsummer, the Upper Midwest is still one of the best lawn growing areas in the country. To the south of us, the broad central part of the country is known as the “Crabgrass Belt” because the conditions for the northern cool season grasses or the southern warm season species are not quite right.

In our region, lawns are healthiest if we follow and support the natural growth cycle of our cold year grasses. In the spring, the roots are long and full of nutrients from last fall. The grass uses this stored energy for spring growth. When the warmer temperatures hit in summer, leaf and root growth slow down and the plants rest in the heat and drought. When the temperatures cool down again in early autumn, the grass becomes highly active, grows stronger and stores nutrients in the long roots.

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Lawn care should follow these seasonal cycles to be in harmony with the natural rhythm of the grass. For example, fertilizer is best applied during the grass’s most active growth cycles in May and September.

Below is a monthly lawn calendar based on recommendations from North Dakota State University and the University of Minnesota.

  • When the lawn is dry enough to kneel down without getting wet, rake the lawn.
  • Start mowing as needed in late April. The grass can be cut shorter for the first spring mowing.
  • Apply crabgrass pre-emerging protectants just before the soil temperature reaches 50 degrees, which is a trigger for crabgrass seeds to germinate.
  • Sow lawns or repair bald spots after the soil temperature reaches 50 degrees.
  • Scarifying, also known as power raking, can be carried out at the beginning of May, when the lawn is stable enough to prevent grass damage.
  • Core aeration, which lifts small plugs of soil and turf out of the lawn, is useful when the lawn is severely clogged by heavy soil, traffic, or thatch.
  • Fertilize the lawn when it is green, is actively growing and can best utilize the supplied nutrients. Memorial Day is an easy target date to remember.
  • Spray weeds selectively when they appear. Liquid herbicides are more effective than weed and feedstuffs.
  • After emergence, apply a crabgrass killer to any visible crabgrass seedlings while they are still small.
  • Increase the mowing height to 3 inches for the healthiest lawn.

    Maintaining a mowing height of 3 inches will keep the lawn healthy.  Michael Vosburg / Forum picture editor

    Maintaining a mowing height of 3 inches will keep the lawn healthy. Michael Vosburg / Forum picture editor

  • The optimal amount of water for optimal lawn growth is 2.5 cm per week, either by rain or sprinkling, applied in one application. In the case of light and sandy soils, the amount can be divided into two sprays.
  • Maintain a 3-inch mowing height that will shade grass roots, keep the soil cooler, conserve moisture, and be more likely to stay green in the summer heat. Low-cut lawns will get hot and dry and will turn brown more easily.
  • Avoid spraying weeds during the summer heat, which can adversely affect grass plants.
  • Do not fertilize in the summer heat, especially if the lawn has turned brown from heat or drought.
  • When watering the lawn, water deeply and less frequently by applying 1 inch of water in one application once a week to encourage deep rooting. Frequent shallow spraying causes shallow roots and wastes water.

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  • Keep pouring deeply as you spray rather than often and shallowly.
  • From the end of August to September lawns can be de-stalked or aerated.
  • Sow lawn or fix bald spots before mid-month. The first half of September is the most successful time of the year for lawn sowing.

    When choosing lawn seeds, check the label to make sure it contains at least 50% Kentucky bluegrass.  Michael Vosburg / Forum picture editor

    When choosing lawn seeds, check the label to make sure it contains at least 50% Kentucky bluegrass. Michael Vosburg / Forum picture editor

  • Fertilize around Labor Day, the main fertilizer of the season, and feed grass plants to develop a deep healthy root system and thick lawn.
  • September is the most effective month for weed control. For hard-to-control weeds, reapply a herbicide in the fall and spring or early summer.
  • Gradually decrease the final mowing height from three inches to 1 1/2 or 2 inches.
  • Protect the lawn from damage by voles by placing rodent bait or traps in PVC pipes located in areas where voles have been seen. Granular fertilizers applied in October can also repel voles.

Don Kinzler, a Lifelong Gardener, is the North Dakota State University Extension gardener for Cass County. Readers can reach him at [email protected]