Why Are There So Many Grass Seeds?

What we call “lawn grass” covers a variety of plants from several genera. We typically divide lawn grasses into two broad categories: cool-season and warm-season. In our area, cool-season grasses are grown almost exclusively, since our winters are at the limit of tolerance for warm-season grasses. Four species account for almost all of the seed planted in our area: Kentucky bluegrass, perennial ryegrass, tall fescue and fine fescue. The roots of these grasses start growing when temperatures reach about 50 degrees; the shoots start growing quickly when the temperature is in the 60s. As the thermometer reaches 80 degrees, growth slows and the grass becomes dormant in high summer heat.

As you can see from the accompanying table, each variety of grass has different characteristics. The

Source: Cornell University Extension

first important distinction is between sun and shade. Unfortunately, there are few plants that will grow in both full sun and deep shade—including grasses. So if you have a typical lawn (a grassy patch surrounded by trees), you probably have full sun at the center and shade at the edges. This is why sun/shade mixes were developed.

Grass requires sun. When we refer to “shade,” we really mean at least four hours of dappled sun daily. If you get less sun than that, you can sometimes prune your trees to allow more light to reach the grass. If you have deep shade, a groundcover such as pachysandra or mulch is a better choice.

While a sun/shade mix is generally the best choice for the varied conditions of a lawn, you may want to choose a single grass to meet the conditions of a specific area. When you’re filling in patches in the shade, you could use fine fescue alone or a shade mix. Similarly, a sunny spot will do well with Kentucky bluegrass or almost any mix.

Sometimes sun vs. shade is not the only consideration. If you have kids frequently playing on the lawn, rugged quick-growing tall fescue may be a better choice. This is also a good choice for a slope, and has the benefit of better drought tolerance. However, because tall fescue is a coarser grass, it doesn’t have the silky appearance that a fine grass has. If you want a strong, low-maintenance lawn, a blend of 65 percent tall fescue (combined with 15 percent perennial ryegrass and 20 percent Kentucky bluegrasses or something similar) is a good choice.

The grass that we grow for our lawns was originally brought from Europe along with the animals that like to eat it; these grasses quickly replaced our native grasses. As many of us have become more interested in native plants, there has been renewed interest in buffalo grass, which originally covered the Great Plains. Buffalo grass is a warm-season grass, but can be grown in our area. Except for seedheads, it stops growing at 4 to 6 inches, so it requires little mowing. There are some problems in planting buffalo grass, however: it requires full sun. It is also killed by traditional lawn weed controls; hand weeding is usually necessary.

Planning for a Beautiful Lawn (Part 4)

Pest and disease control

Over the last few weeks, my blogs have covered several aspects of caring for your lawn. I’ve discussed the importance of core aeration, compost and mowing; fertilization and weed control.

The healthier your lawn is, the more likely it is to resist pests and diseases. Some pests, however, can be hard to avoid—particularly white grubs. Grubs are the larvae of beetles (primarily Japanese beetles and masked chafers) that develop in the ground. When the population of grubs is significant, you will start seeing brown patches in your lawn, particularly toward late summer. To make matters worse, grubs are a delicacy for some animals, such as skunks and raccoons. Sometimes the problem goes unnoticed until you see holes dug in your turf one morning. Grubs like sunny areas with moisture, and are not often found in shade or in dry lawns.

If you see brown patches in your turf, you can lift up a piece of turf where the brown patch meets green lawn and look at the roots to check. The grubs are white and C-shaped. It only takes about 10 grubs per square foot of lawn to cause visible damage.

If you catch the problem early, or if you see a large adult population of beetles,  Almstead lawn technicians usually perform a summer lawn treatment.  Although mid-summer and fall treatments are sometimes effective, June is the best time to prevent grubs from damaging your lawn.

There is also an effective organic treatment for grubs which we use, which utilizes milky spore, a grub-killing bacterial powder. However, this only works on Japanese Beetle grubs and must build up in your soil over time to work. We can test your lawn to identify what type of grub is living there.

Other insects, such as chinchbugs, can be damaging to lawns. When you see yellowing patches, or grass blades that have been notched and nibbled, we try to identify the insect responsible and narrowly target it with the appropriate control.

Lawn diseases are usually fungal. Fortunately, they are not common. Unfortunately, they can be difficult to diagnose and can spread quickly. If you suspect your lawn is suffering from disease rather than insect damage, it's wise to have a sample taken and analyzed in order to determine the right treatment.

The best prevention for lawn disease and pests is maintaining the health of the lawn. A well-nourished, watered, well-mown lawn becomes a self-sustaining system that is hostile to predators.

- Ken Almstead, arborist and CEO

Planning for a Beautiful Lawn (Part 3)

Weed control

Over the last two weeks, my blog has covered the basics of preparing your lawn in spring and how and when and how to fertilize it. This week, I’ll talk about weed control. The next blog will cover pest and disease control.

There is no universal definition of a weed. You may be content to see clover among the grass stalks in your lawn, while someone else reaches for the Roundup. Some people carefully scrutinize their lawns and remove any undesirables with tweezers while others are content as long as the weeds are green. Is it enough to eliminate the crabgrass and broadleaf weeds and leave some clover mixed in your lawn? Or do you want a lawn as luxuriant as a golf course green?

Frankly, having a completely weed-free lawn is setting the bar rather high, and will require frequent application of weed control products. Since most herbicides are synthetic, a totally weed-free lawn is not compatible with an organic-only care philosophy. 

There are two major categories of weed control: pre-emergent and post-emergent. The pre-emergent treatments prevent seeds from germinating. This helps control weeds like crabgrass, which begin from seed each year. There are several kinds of synthetic pre-emergent products available. Pre-emergent herbicides won’t do much to get rid of plants like dandelions that overwinter in your lawn and spread through roots.

Post-emergent herbicides target broadleaf weeds, such as dandelions, plantain and ground-ivy.  Some can be applied to the entire lawn; others are made to squirt directly onto the offending weed.  The herbicide will be absorbed into the weed and kill it off, roots and all. Be careful – it will kill anything it touches with leaves, including your annuals and perennials.  

There are no comparable herbicides in organic care. Ideally, as you create a healthier environment for grass, it will become harder for weeds to compete. Weeds tend to thrive and out-compete grass in compacted soil—which is why annual core aeration is a good technique. There are organic vinegar-based  spot-herbicides that can be sprayed on weeds—but they can kill grass as well, if you’re not careful. Perhaps the best organic practice is to pull weeds by hand. There are several hand tools designed to remove weeds; just make sure you extract the entire root or the weed will grow back.

How often you apply weed controls depends upon your philosophy and your budget. Although pre-emergent controls are usually applied in early spring, the post-emergent controls can be applied as you notice the weeds appearing. You can just use them in the areas where weeds are apparent. They are usually applied when the lawn is dry; they need a few hours free of rain or watering. When Almstead provides lawn care to our clients, we typically offer two applications of pre-emergent herbicide in spring, and then follow up with monthly inspections, applying post-emergent controls as necessary.

Hand-pulling weeds is usually easiest when the ground is moist. If you intend to compost the weeds, make sure you turn your compost pile often and that it gets warm enough to kill the seeds (over 131 degrees). Otherwise, you’ll wind up cultivating them rather than killing them.