Their bags and boxes may look much the same. But, the products sold as lawn seed are not all "created equal."

"Choosing a quality seed is one of the most important steps a homeowner can take in planting or overseeding a fescue or bluegrass lawn this fall," said Ward Upham, Kansas State University Research and Extension horticulturist. "An improved variety or mixture of improved varieties can provide everything from a deeper-green lawn to better drought-resistance."

Quality seed also tends to come with fewer unwanted "extras," such as a percentage (by weight) of weed or pasture grass seeds, Upham said.
So, it costs more.

"The cheapest turf seed available around Kansas is always K-31 tall fescue. It's hardy and drought-resistant and will grow in light shade. It's also the old variety than can give tall fescue a bad name. It's got coarse leaves that grow fast – you may feel as if you've got a hard job of mowing all the time. It also tends to form bunches when stressed, which leaves more room for weeds and makes people think about overseeding again," he said.

Two legally required label entries that lawn seed buyers should always check are the container's percentage of weed seeds and its percentage of "other crop" seeds, Upham said. Unless an unwanted plant's seeds add up to 5 percent or more of total seed weight, the bag will not list the species by name.

"Other crop" can be any grass species that's intentionally grown for some purpose. It can be a turfgrass other than the one the bag is selling. It can be a grass that's grown for animal forage.

If this stray grass is a perennial, homeowners probably will not be able to control it selectively, he warned. They'll have to hand-pull it. Or, they'll have to kill both it and the turfgrass.

"Obviously, if your expectations are high, you don't want any weed seed content," Upham said. "You probably won't be able to find any seed with zero ‘other crop,' however – although seed producers are always striving for that.

"Even so, if you can afford it, you should opt for the seed that has the ‘other crop' listing that's closest to zero."

The horticulturist cited these common examples of "other crop" problems, warning that "even less than 1 percent of some crop grasses can ruin the bag":

Orchardgrass is more typically a problem in tall fescue, where it quickly makes its presence known with a coarse texture and rapid growth rate. A perennial plant, orchardgrass creates a rough, messy surface each time it grows up above the rest of the lawn.

A tall fescue bag that contains 0.5 percent – one-half of 1 percent – of the fast-growing pasture seed will average "planting" 12 to 16 orchardgrass seeds per square foot of lawn.

Rough bluegrass – also known by its Latin name, Poa trivialis, or the nickname Poa triv – is more commonly an "other crop" for Kentucky bluegrass. Despite its name, it is a fine-textured perennial that blends in fairly well as it forms circular patches in the lawn each spring. With summer's heat, however, it rapidly goes dormant, creating brown spots. Yet, it rarely dies, so turns green again with fall's cooler temperature and rain and emerges again the following year.

Kentucky bluegrass seed containing 0.5 percent rough bluegrass, will distribute an average 25 to 35 seeds of this heat-intolerant "crop" per square foot.

Perennial ryegrass looks similar to bluegrass but is a bunchgrass (like tall fescue) that gets established very quickly. It's basically no problem – not only because of its looks but also because it's less heat-, drought- and cold-tolerant than fescue or bluegrass, so rarely remains in the lawn for long.

K-State Research and Extension is a short name for the Kansas State University Agricultural Experiment Station and Cooperative Extension Service, a program designed to generate and distribute useful knowledge for the well-being of Kansans. Supported by county, state, federal and private funds, the program has county Extension offices, experiment fields, area Extension offices and research centers statewide. Its headquarters is on the K-State campus in Manhattan.