col Keeping lawn healthy starts with understanding

By Holly Laures

Olmsted County Extension Service

Have you ever wondered what your lawn actually is?

It is actually made up of millions of individual turfgrass plants. These plants grow very close to one another and make up what you call your lawn.

Have you ever wondered what the ultimate secret is to having the best looking lawn on the block? It is not necessarily lots of fertilizer and lots of water. The best thing you can do for your lawn is to understand how your turfgrass lives and grows. Armed with that knowledge and a soil test, you will have everything you need to know to have a healthy, vigorous lawn.


The grasses that are used in lawns in our state are known as cool season grasses. This simply means that they actively grow during the cool seasons and reduce growth or go dormant in hot conditions. Following are the typical growth habits of lawn grasses based on season.

Spring: Lawns go through a period of rapid vegetative growth. The plants use energy they have stored in them from the previous fall to accomplish this. Quick release nitrogen fertilizers, in spring, can actually stress your lawn. Because they force the grass to grow more rapidly than their food reserves can be replaced. When the hot dry weather comes, these lawns are more apt to be stressed. The period of rapid vegetative growth is usually necessary to get the plants ready to flower. Yes, grass plants do flower, but because of common mowing practices most people never notice.

Summer: Lawns tend to thin out as old mature grass plants die. After grass flowers, the stems and roots that were grown to support that flower die back. Even though shoots are constantly being replaced, some thinning may be noticed around mid-summer. Just after that time period, lawns in Minnesota usually go into summer dormancy. It is a common misconception that when the weather gets hot and dry our lawns die. Actually, they do not. They go dormant until a specific environmental condition is met, which in our case is the cool moist weather that fall brings. To keep your lawn as healthy as possible during this season, you should raise your mowing height to reduce stress on your lawn and to shade out warm season weeds such as crabgrass.

Fall: With cooler temperatures and more frequent rainfall, grass plants begin to grow again. During the fall season your lawn goes into a compact vegetative growth habit and begins producing daughter plants. When fall comes, you should shorten your mowing height to help promote a dense lawn.

Fall is when seeding, sodding, fertilizing, aeration, dethatching and broadleaf weed control should be done. Fertilizing needs and timing are best determined by a soil test. Grass will utilize fall fertilizer applications for growth and production of new plants to replace those that die during the summer. Carbohydrates will also be stored for winter survival and early spring green-up.

Keeping your lawn healthy can do more than just make it look good. A healthy lawn is better equipped to fight off an attack by insects, diseases and weeds. A healthy dense lawn is also good for our environment because it will filter pollutants and protect topsoil from erosion.

For more detailed information on this topic, you can visit, and the maintenance and lawns category at You can also call the University of Minnesota Extension Service, Olmsted County at 285-8253.

Holly Laures is an intern at the University of Minnesota Extension Service, Olmsted County.

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