Is there such a thing as the perfect lawn-lush, dark green carpet? You may not ever achieve “the perfect lawn,” but you can come close if you know some basic facts about the three main types of grass.
The three types of turf grass that thrive in the Midwest are cool season grasses and consist of Kentucky bluegrass, perennial rye and fine fescue. Various blends of these grasses have been developed to grow in different environmental conditions.
Kentucky bluegrass, Poa pratensis, is the most widely planted and recognizable of the grasses. This grass has dark green, medium blades. It does best in full sun (six hours or more), requires moderate fertilization and moisture. It thrives in the cool, moist spring and fall and can go dormant during drought conditions in July and August.
If the drought is not severe, the grass will green up in the fall as the weather cools off and the rains return. The plant spreads by runners or rhizomes. Research has found that one healthy plant may spread to cover up to one square foot. In the 1990s, extensive research was done in hybridizing darker green, more vigorous disease resistant varieties that far surpassed the common Kentucky bluegrass from earlier years.
Perennial rye grass, Lolium perenne, is the second most planted grass. It is native to Europe and is also a cool season grass. Unlike bluegrass, which spreads, perennial rye grass has a more upright bunch-type growing habit. It is a tougher grass in that it can withstand more wear and tear from foot traffic, will survive poorer soil conditions and dry spells. Perennial rye which comes back year after year should not be confused with annual rye, which is a one-year grass and will not come back after the winter season.
The third type of grass for this area is creeping red fine fescue, Festaca rubra. It is not creeping and it is not red; however, the blades are very fine almost like hair. This grass is very drought and shade tolerant. Because of the fine blade structure, this grass does not bounce back so it is not recommended for areas where there is a lot of wear and tear.
Blends of these three grasses fit most lawns. Seed germinates at 50 degrees or more with moisture. Germination rates are rye grass five to seven days, fescue is 10 to 14 days and bluegrass is 14 to 20 days. In a good soil and full sun, the blend should have a higher percent of bluegrass. Heavy clay soil with tough growing conditions will do better with more perennial rye.
Grass blends for shady or sandy soils will be called “shady mix” and will have a higher percent of fine fescue. Inexpensive mixes will often have more annual rye which germinates quickly but will not come back next year.
I cannot talk about lawns without addressing the fourth dreaded grass…crabgrass. This grass is an annual weed grass, which comes up new from seed every spring. Studies show that in the summer one plant can produce more than 100,000 seeds. In the winter the wide flat blades of crabgrass turn white and are easily spotted in the lawn.
In the spring, seeds will germinate where there are bare spots. By maintaining a healthy thick lawn with good grasses and proper fertilization, crabgrass has a hard time becoming established. If crabgrass preventer is needed, it needs to be applied when the soil temperature is 50 degrees and the crabgrass seeds are starting to germinate. If weather conditions are ideal for new seed to germinate, crabgrass will sprout throughout the summer.
Do not apply new grass seed and crabgrass preventer at the same time in the spring.
Margo Hansen is the Director of Programs at Bickelhaupt Arboretum.