David Robson: Beware before buying grass seed

David Robson

"Let the buyer beware.” That’s a perfect motto for buying grass seed.

Maybe it would be even better to say, “Let the buyer read the label carefully.” If not, you have only yourself to blame.

Bluegrass, fescue and ryegrass can make an attractive lawn.

Perennial ryegrass, the most common ryegrass, is rather innocuous. It sprouts quicker than you can sing “The Star-Spangled Banner.” (OK, it may take three to five days, but other grasses may take weeks.)

Perennial ryegrass is a weak grass. It grows well only in full sun, and it does not appreciate much foot traffic. Combine ryegrass with another type of grass, and the other grasses eventually will choke it out. Until then, it’s about the same size and color as bluegrass, making it hard to tell the two apart, which is OK for a lawn.

As far as grass seed, you really can’t go wrong with perennial ryegrass in a mixture. Just realize that it has limited longevity, and you’ll be OK.

That leaves us with bluegrasses and fescues.

Fescues are split into two types for lawns: fine fescues, which love the dry shade conditions but don’t like any traffic, and tall fescues, which are among the toughest grasses on the market.

Tall fescues have the most drought and flood tolerance of lawn turfgrasses. Tall fescues also have few insect or disease problems and can withstand foot traffic with ease. In fact, one of the most common pasture grasses is Kentucky-31 or K-31, suited for just about any four-legged livestock.

You can also get by with less fertilizing. Because it’s a bunch grass, once established, it chokes out most weeds.

Of course, there are some downsides.

First, tall fescue is a bunch grass, which makes it harder to get established. Bluegrass spreads by rhizomes, which means it can fill in quickly.

Tall fescue, for the most part, has wider grass blades, which can be another big problem. Crabgrass is a problem because the leaf width is about 10 times the size of bluegrass. Tall fescue, especially common types such as Kentucky-31, have leaf blades just a little smaller than crabgrass.

Some turf-type tall fescues have narrower blades, approaching maybe a third larger than bluegrass. However, over time, if they aren’t kept in a juvenile stage, they will start developing wider stems, much like humans do as they age.

If you have an all-tall fescue yard, you may notice the coarse-texture of the leaf blade, though that depends on the size of your yard. It’s sort of like an elephant in a school gymnasium compared to the same elephant in your bathroom.

In other words, having tall fescue in a bluegrass lawn and vice versa isn’t something you want.

Essentially, tall fescue looks clumpy in a typical bluegrass lawn. And because tall fescue and bluegrass are both perennial grasses, we have no easy control of one without affecting the other. You can spot treat with some herbicides such as glyphosate (Roundup and Kleenup), but you have to be more careful than the typical homeowner.

This is where “buyer beware” comes in.

Many packaged seed mixes contain bluegrass and ryegrass. That’s OK. Others contain ryegrass and tall fescue. That’s OK. Sometimes the fine fescues are thrown in both mixes, which is also OK.

The problem comes when people have one type of grass, usually bluegrass, in their lawns and don’t read the packages.

First, some packages say Kentucky-31. Most people associate Kentucky with bluegrass. We’ve gone out of our way to avoid putting the two together here. But reality is reality. If you see

Kentucky-31 on a shelf, and you have a thinning bluegrass lawn, you’ll mistakenly consider it the same type of grass. The next thing you know, you have large clumps of tall fescue.

Other packages may espouse “Low Maintenance” or “Easy Care,” with a lush lawn on the package. Again, you’re fooled into thinking all grass is the same. By state law, packages must specify the type of grass seed on the label.

If you have a bluegrass lawn, avoid tall fescue grass mixes. You’ll hate yourself during the summer when you see bunches of tough-looking grasses staring back at you.

If you have a tall fescue lawn, or want to start a pure tall fescue lawn, go with the tall fescue. Bluegrass might look good for a bit, but ultimately, it will look awful.

Above all, read the labels carefully for the type of grasses, and avoid mixing bluegrass and tall fescue.

David Robson is a horticulture educator for the University of Illinois Extension. For more gardening information, go