Grass seed selection can be a daunting decision without knowing the different grasses’ attributes or how they will perform. Most home lawn seed mixtures are only divided by sun or shade needs, but other characteristics of different grass species can better match your particular needs and the amount of maintenance you are willing to provide.
In Connecticut, the most limiting factor to consider is the low temperature tolerance. The grasses that will live through our winters are called cool season grasses. These are Kentucky Bluegrass, Rough Bluegrass, the Bentgrasses, the Fine Fescues, Tall Turf Fescue, and Perennial Rye. Zoysiagrass is a warm season grass that will survive our winters, but will only look good and green during the hottest three months of the year. More about Zoysiagrass later.
Two annual grasses are sometimes seen in grass seed mixes. Annual Rye grass and Annual Bluegrass should not be planted as they will only live for one summer, then die with the cold weather. Annual Rye germinates very quickly making it good for erosion control or a quick, temporary lawn. It is often sold as ‘Contractor’s Mix’ to provide a good looking lawn to aid in selling a newly constructed house, but the lawn will be dead after the winter. Annual Bluegrass is a weed grass capable of producing very high numbers of seed and very commonly present as a lawn weed invader. It has a lighter green color most find undesirable.
Cool season grasses can go dormant during drought and heat of summer. When lawns look brown in August, they are not usually dead, only dormant. They will revive and turn green when irrigated and/or cooler temperatures arrive. Heat tolerance varies among species with Tall Turf Fescue being the most heat tolerant.
It is best to plant a mixture of grasses for a lawn, to provide diversity against an insect or disease that attacks one species of grass. If a pest kills off all one type of grass, there will still be other varieties left unaffected in the lawn, rather than taking down the entire lawn. Sun mixtures often include Kentucky Bluegrass, Perennial Ryegrass and Tall Turf Fescue. Shade mixes are designed for areas receiving at least four hours of sun per day, not complete shade. Fine fescues, Tall Fescue and Rough Bluegrass and some varieties of Kentucky Bluegrass are commonly included in shade mixtures.
Attributes of grass types:
Kentucky Bluegrass, (Poa pratensis) - Has dark green color, vigorous rhizomes(underground stems) for good spreading and repair after injury, full sun tolerant, medium texture with high density, good wear tolerance, excellent low temperature tolerance but will go dormant in drought and heat, needs well-drained, moist soil.
Problems are poor shade tolerance, poor salt tolerance, tends to build up thatch and susceptible to insect and disease attacks, especially when mowed low.
Rough Bluegrass, (Poa trivialis) - has sod-forming stolons,(above ground stems), not as vigorous as KBG, shade loving, color is yellow-green, fine to medium texture, loves wet and shady site, rapid establishment rate. Low fertilizer inputs needed. Good for side of road, conservation areas or areas not needing mowing.
Problems are poor drought tolerance, very poor wear tolerance, undesirable color, poor salt tolerance. Not recommended for home lawn mixes.
Bentgrasses: Creeping Bentgrass, Colonial Bentgrass and Velvet Bentgrass – Bentgrasses are used on golf courses and athletic fields. They produce a uniform turf when mowed at very low heights, as low as .25 of an inch. When cut high as in a home lawn, they produce tufts of grass higher up on the stem, then flop over. They also require a very high level of maintenance, fertilizer and water. For these reasons, Bentgrasses are not recommended for home lawns.
Fine Fescues: all have very narrow, bristle-like blades, very fine texture.
Creeping Red Fescue, (Festuca rubra) – Sod forming rhizomes mix will with KBG and perennial ryegrass. High density,excellent drought tolerance, excellent shade tolerance, tolerates dry, sandy, low pH, low fertility soils.
Problems are fair wear tolerance and poor recuperative ability after injury. Does not tolerate wet soils. Can build- thatch, off color in summer heat, over water and over nitrogen fertilization reduces quality and persistence.
Chewings Fescue, (Festuca rubra var. commutata) - A bunch type grass extremely similar to Creeping Red Fescue except is does not spread due to having no rhizomes.
Sheep Fescue, (Festuca ovina) A bunch type grass with bluish-gray color with low-tufted growth. Extremely drought tolerant, excellent shade tolerance, requires low nitrogen inputs.
Problems are poor wear tolerance and recuperative ability, only fair high temperature tolerance, declines under higher nitrogen rates and irrigation.
Hard Fescue, (Festuca trachyphylla) - A bunch type, low maintenance grass extremely similar to Sheep Fescue except it tolerates a higher moisture soil.
Tall Turf Fescue, (Festuca arundinacea) - Bunch type grass with short rhizomes, medium to dark green color, drought tolerant, better varieties have finer texture and thinner blades, good wear tolerance and recuperative potential, deep rooted, good heat tolerance, retains green color during heat stress, shade tolerant. Excellent salt tolerance, low to moderate fertility needs.
Problems are only fair cold temperature tolerance, susceptible to grey leaf spot disease and can become tufted when mowed infrequently. Older varieties and utility grade have much coarser texture.
Perennial Rye, (Lolium perenne) - A bunch grass with profuse tillering, seed germinates quickly for fast establishment, medium to dark green color, medium to fine-leaf textured cultivars available, good wear tolerance and good recuperative ability. Does best with cool summers and mild winters.
Problems are poor shade tolerance. Tough stems make it difficult to mow cleanly leaving ragged-edged blades. Can out compete other grasses leading to only one type of grass in the lawn. Susceptible to grey leaf spot disease.
Zoysiagrass, (Zoysia japonica) – A warm season grass the lives through Connecticut winters. Zoysia is very late to green up in the spring and goes dormant early at the end of the summer. Great drought and heat tolerance, tough leaves provide excellent wear and recuperative ability. Low fertility and low pH tolerant, salt tolerant too. Spreads by rhizomes and stolons.
Problems are it tends to build up thatch, will not grow in very moist soil, is very aggressive to the point of crowding out all other grasses. And it will only be green during the hottest three months of the year.
Inclusion, all of the above grass species have many different cultivars with varying attributes as plant breeder are constantly developing newer and better seeds for the American lawn.