Solving Lawn Problems: Part 2, Cool Season Grasses
By: Dale Mermoud, Master Gardener

This article is the second in a series of three articles and covers some of the problems and/or solutions for cool season lawns. Cool season grasses include fescue, blue grass, and rye grass.

The advantages of cool season grasses are: a green color year round (severe winters may cause browning), performs well in shaded areas. Disadvantages are they do not stand up well in high traffic areas or compacted soils, will become dormant and not grow during hot months of July to September unless watered well, long growing season may require mowing from March to November.

Now is the time to start caring for your cool season lawn. Some activities to perform are:

March: mow at 1-1/2 or 2 inch level, or rake to remove excess growth, remove leaves, this allows the soil to warm and promotes faster green-up; over seed bare or thin spots; apply broad leaf weed killers for winter weeds; apply crab grass killer.

April: mow at 2-inch height; aerate heavy soils or compacted areas.

May: fertilize only if growth is slow; apply herbicides for summer broadleaf weeds, mow at 3-inch level.

June to August: may need to begin watering (apply 1 inch per week); mow at 3-1/2 to 4 inch level, mow frequently to keep clippings small; let clipping remain unless excessive.

September: fertilize with a balanced lawn fertilizer; seed bare spots; aerate compacted areas; mow at 3 inches.

October-November: apply broad leaf herbicides; apply lime according to soil test; remove falling leaves so they don’t smother grass; mow at 2 inch level; may apply a second fertilizer application if all was not applied in September.

To seed a new lawn or renovate an existing lawn is a problem only the homeowner can decide. The decision to renovate is when an existing lawn contains less than 50 percent of the desired turf grass. For smaller areas, spot renovation may be practical.

In either case kill existing vegetation with a roundup herbicide (or a glyphosate herbicide) beginning the first of August. Apply a second herbicide application in 14 days to kill escaping or newly germinated weeds. It may be necessary to water the existing weeds/problem areas to establish good growth for the herbicide to be effective. Set the mower as low as possible and cut remaining vegetation and rake clean. Prepare the ground by tilling or power rake. Remove this debris, add fertilizer, lime, and/or amendments (from previous article) according to soil test and till. Rake the area smooth and apply seed in 2 directions. Lightly rake or roll the surface to create good soil to seed contact. Water until established. Accomplish this by Sept. 15 to enable plants to establish themselves before winter.

Seed versus Sod. Both methods can produce a beautiful lawn. Sod is more expensive, but it produces a quick, pleasing lawn. Sod may be the only solution to steep banks or areas where erosion is a problem. Sod can be applied any time from April to September. Remember the seedbed must be prepared the same as for seed. Do not place sod on existing vegetation! Sod will need watering to get it established the same as seed.

A problem area of cool season grasses is under large trees. For grasses to grow here may require aeration to relieve compaction, adding soil amendments, and selective removing of interior limbs and low branches to allow more sunlight. Shade tolerant varieties offer another option.

For more information contact the University of Missouri Extension Center to request publications MU Guides G6700, Cool-Season Grasses: Lawn Establishment & Renovation; & G6705, Cool-Season Grasses: Lawn Maintenance Calendar;  and G6725, Grasses in Shade.