Q: What is the best type of grass to plant for a low-maintenance lawn here in Western Pennsylvania? We are looking for something beautiful and durable, something that would not require a lot of chemical inputs such as insecticides, fungicides and synthetic fertilizer. Is there such a beast?

A: Unfortunately, there is no one-size-fits-all answer to your question. As is true for any plant, it is important to choose the right type of grass for the conditions in your yard. How much sun does it receive? Is the soil well drained, or does rain collect in certain areas? Do you have a sufficient base of topsoil, or do you have mostly heavy subsoil?

Four to 6 inches of topsoil is important for a healthy, lower-maintenance lawn because decent topsoil drains well while retaining sufficient moisture. Good soil structure is important for grass to produce an extensive healthy root system.

Are you willing to water when we get into hot, dry weather in summer months? Some grasses are more drought-tolerant than others, but all lawns will brown out when we go for weeks without rain. A soil test will reveal your soil's chemical characteristics -- the level of specific nutrients and soil pH (acidity or alkalinity). These can be adjusted by tilling in the required amendments prior to planting. Grasses with lower fertility requirements can get by with a single application of fertilizer, especially if you use a mulching mower and leave the clippings on the lawn. Grasses also vary in their tolerance to hot, humid weather, as well as to their winter hardiness.

It is also important to consider how your lawn is used. Do all the neighborhood kids play in your yard? Do you have large dogs? Or is weekly mowing the most foot traffic your lawn sees? Some varieties of grass stand up to heavy use better than others. Lawns that see a lot of use generally require a higher level of maintenance -- particularly fertilization and irrigation -- than those that do not to help them recover and stay healthy.

In the Pittsburgh area, we generally grow cool-season grasses such as Kentucky bluegrass, perennial ryegrass, fine fescues and turf-type tall fescue. These grasses are adapted to our winter weather and typically put on the most growth in the cooler weather of spring and fall. Unless they receive supplemental water during hot, dry, summer weather, they go semi-dormant.

Warm-season grasses are grown in the southern United States. Zoysia is the only warm-season grass we can grow in our area. Most lawn experts do not recommend it here because it turns brown at the first frost and stays brown until late spring or early summer. That said, I know people who love their zoysia lawns.

Here is a brief rundown of each grass's strengths and weaknesses:

Kentucky bluegrass (Poa pratensis) is considered by many to be the Cadillac of lawns while others say it requires too much maintenance. It has a medium to fine texture, good color and tolerates wear and winter temperatures well. It also tolerates our clay soil better than most other grasses.

It spreads by rhizomes (underground stems) that create a dense sod and allow it to recover from wear, drought or insect and disease damage better than other cool-season grasses. On the downside, Kentucky bluegrass requires a higher level of fertility than the others for optimum performance. That means 3 to 4 pounds of nitrogen per thousand square feet in three or four applications through the growing season. Although its rhizomatous growth habit allows it to recover from damage better than other grasses, it also allows faster thatch build-up.

Thatch is a tangled mat of sloughed-off stems, roots and rhizomes produced as grass grows. A thick layer of thatch interferes with the movement of water though the soil and can act a breeding ground for insect and disease problems. Kentucky bluegrass seed can be slow to germinate, taking two weeks or more. It grows best in full sun and well-drained soil, and prefers a mowing height between 1 1/2 and 2 1/2 inches.

Perennial ryegrass (Lolium perenne) has a fine to medium texture and dark green color. It tolerates wear and hot weather well. Perennial rye seed can germinate in five to seven days under optimum growing conditions and establishes quickly. It grows aggressively and is often used to repair damaged lawn areas. It tolerates cold weather but can be severely damaged by ice as well as extended drought.

This is a bunch-type grass that does not spread by rhizomes, which means it does not recover from damage as well as Kentucky bluegrass. It also means it does not build up thatch as quickly. It requires 3 pounds of nitrogen per thousand square feet in three applications through the growing season. Perennial rye is best in full sun and well-drained soil and prefers a mowing height between 11/2 and 21/2 inches.

Fine fescues (Festuca spp.) include creeping red fescue (F. rubra), Chewings fescue (F. rubra var. commutata), hard fescue (F. longifolia) and sheep fescue (F. ovina). These are the finest textured grasses and have a medium to dark green color. They tolerate shade, low fertility and low pH (acidic) soil. They do not tolerate hot, humid conditions, poor drainage or heavy wear. Some can build up thatch quickly.

Creeping red fescue spreads by rhizomes and can fill in damaged spots like Kentucky bluegrass. The others are bunch-type grasses. Hard fescue is slow to germinate while the others are moderately fast. Sheep fescue is primarily used in low-maintenance situations such as golf course roughs and is not often used for home lawns.

Fine fescues require 1 to 2 pounds of nitrogen per thousand square feet in two or three applications through the growing season. They are best in some shade (not dense, all day shade) and well-drained soil and prefer a mowing height between 2 and 3 inches.

Turf-type tall fescue (Festuca arundinacea) is a relatively recent development. Plain tall fescue has long been used as a pasture grass. A cultivar called 'Kentucky 31' has been grown successfully on extremely difficult sites such as highway median strips. It is too coarse to be considered a good lawn grass, but turf hybridizers have worked to refine the appearance.

The result, turf-type tall fescue, is less coarse and has a darker green color. It is slow to establish its deep and extensive root system and should be watered during hot dry weather for at least its first growing season. It still has a coarser appearance than the above-mentioned grasses and should be used alone to avoid a clash in textures.

This is probably the least thatch-producing grass used for home lawns. It requires 2 1/2 to 3 pounds of nitrogen per thousand square feet in two or three applications. It prefers full sun to part shade and well-drained soil, and a cutting height between 2 and 3 inches.

Zoysiagrass (Zoysia japonica), the only warm-season grass seen here, puts on the most growth during the heat of summer. It can form a dense, weed-resistant turf and is drought tolerant once established.

Zoysia spreads aggressively and can make a pest of itself in flower beds and shrub borders. It is a prolific thatch producer and should be dethatched yearly. It requires only 1 to 2 pounds of nitrogen per 1,000 square feet in two applications.

Meyer zoysia is the only variety of zoysia recommended for Pennsylvania. It is best in full sun to partial shade and well-drained soil, and prefers a mowing height of 1 inch -- much lower than any of the cool-season grasses will tolerate.

With the exception of turf-type tall fescue and zoysia, it is rare to grow a single species of grass in a lawn. By planting different species of grasses together, you ensure that some portion of your lawn will survive drought, insects or disease. A good shade mix will contain a high percentage of fine fescues with a shade-tolerant Kentucky bluegrass cultivar such as A-34 ('Bensun'), 'Bristol,' 'Eclipse,' 'Glade,' 'Nugget,' 'Touchdown' and 'Victa.' If an area is only moderately shady, turf-type tall fescue can also be used.

For full sun, a mixture of Kentucky bluegrass and perennial ryegrass is best. You may encounter something called "Penn State Mix." This is simply a mixture of grasses long recommended by Penn State's agronomy department for home lawns; Penn State does not sell grass seed.

The basic mixture is one-third Kentucky bluegrass, one-third perennial ryegrass and one-third fine fescue. Different suppliers use slightly different percentages of each grass species. It is best in full sun but can also be used in light shade.