Growing Green: Summer Lawn Care
With this odd start to the summer season, many seem confused about this season’s lawn care. What is an appropriate mower height? How often and how much should I water? When is the best time to fertilize, dethatch and renovate existing lawns? For the answers to these questions, you first need to understand the growth cycle of turf grass.
Most lawns in our area are cool season grasses, which include Kentucky Blue Grass, Perennial Rye Grass and Fine Fescues. These grasses naturally slow their growth and may go dormant in the hottest of summer months. With this in mind, you need to decide whether to water religiously throughout the summer, or allow your grass to go dormant. If allowed to go dormant, lawns only need about ¼ to ½ inch of water every 2 t o 3 weeks to keep their root and crown tissue alive. If you want a green lawn all summer long, water deeply and infrequently; applying about 1 to 1 ½ inches of water once a week. Do not allow lawns to turn brown and then water them back to a green condition, as this depletes energy reserves and stresses the plant.
The rate at which you water will affect the rate at which you mow. The general rules for mowing are:
1. Mow High: The higher the cut, the less maintenance required. Higher heights promote deep root growth. Deep roots have greater access to water and nutrients in the soil, which increases their ability to tolerate environmental stresses. For most lawns, mowing at a height of two to three inches is best.
2. Mow Frequently: Mow often enough so that no more than 1/3 of the grass is removed at one time. If you remove more than 1/3 of the grass blade, your lawn will likely look brown after mowing. The grass will use energy and nutrients to produce new leaves, resulting in a weaker root system.
3. Keep Your Mower Blades Sharp: If you don’t keep your mower blades sharp, you will be tearing the grass, rather than cutting it. This will result in a browning after you mow, and leaves the grass open to fungus and other diseases as well as insect invasion and water loss. Grass cut with a sharp blade will recover faster; have better water retention, and increased photosynthesis. Mower blades should be sharpened at least twice each season.
It's best to hold off until later in the season for most other lawn care practices, including fertilizing, seeding, thatch control, and applying weed killers. The period from late August through early September is ideal for many of these practices. For now, help your lawn by proper mowing, watering, and keeping foot and vehicle traffic off the grass as much as possible during the heat of the summer months.
Robin Trott is a Horticulture Educator with University of Minnesota Extension.