We are nearing the end of “No Mow May.” The Department of Natural Resources and many Minnesota communities promote not mowing your lawn in the month of May in order to help pollinators, especially bees, as they come out of hibernation. Not mowing in May allows for a month of steady growth of the grass along with the flowers that we often refer to as “weeds” such as dandelions, violets and white clover. These flowers provide some of the first food (nectar) for pollinators in spring.
If you chose to let your lawn grow longer than usual in May (or any other time) you should mow carefully once you begin. It is recommended that you only mow off 1/3 of the grass blades at a time. So if your grass grew to 6” you want to set your mower to cut off only 2” in the first mowing. Normally, it would be recommended that you leave your grass clippings on the lawn to sift down to the soil and provide fertilizer, but since these longer clippings may just clump on the grass, you want to bag them. A few days after the first mow you can set your mower a little lower to take off another third of the blades. Continue in this manner until your grass height is the recommended 3” tall and you can leave the grass clippings on the lawn. No Mow May can have one detriment for your lawn — by encouraging the vertical growth of the grass you can impeded the horizontal growth. But once you reduce to and maintain the grass height at 3” the vertical growth will speed up.
Growing and maintaining a lawn may be the most labor and resource intensive activities in your yard, and mowing your lawn may be the most time-consuming activities. Mowing properly contributes to a healthy lawn and minimal weeds, and leaving the clippings on the lawn will help the grass nutritionally. Mowing regularly with a sharp blade will help keep grass growing vigorously and densely. (Exceptions to this would be during drought conditions.)
In a typical Minnesota lawn grass should be kept at a height of 3” or longer. Taller grass keeps the soil cooler and shades out weeds. It also means longer roots which can reach nutrients and tolerant drought better. Mowing too short allows weed seeds to get more sun and germinate. Mowing too short or scalping the lawn stresses the plant. Weak grass plants are less drought tolerant and take longer to recover. Remember not to remove more than 1/3 of the leaf tissue at one time, so if you want to maintain a 3” lawn, mow before it gets to 4.5.” You can leave the grass a little longer in mid-summer to reduce the stress of high heat and drying winds.
Leaving your grass clippings on the lawn over the course of the summer is the equivalent of one fertilizer application. The grass clippings improve soil quality, reduce runoff and improve carbon sequestration. If your clippings are too long you can mulch them by running the mower over the lawn a second time, otherwise you should rake them and bag them.
Make sure your mower blades are sharp. Dull blades leave the leaf blades ragged and more susceptible to disease. Clean cut leaf blades are better able to conserve water and reduce the amount of watering needed. If you change the direction of your mowing pattern each time you mow you will promote upward growth and reduce the chances of scalping and soil compaction. Try mowing at 90° angles or even diagonally with every other mowing. Continue mowing until the grass stops growing in the fall, generally in October. Make sure the 3” height is maintained going onto winter. Longer grass under the snow could contribute to disease such as snow mold and vole activity.
Now that the warmer weather seems to have finally arrived, let the mowing begin!