KC Gardens

Read the label before purchasing grass seed

Grass seed label

Tip of the Week

Fall planting time for cool season grasses such as bluegrass and tall fescue is close at hand, so it’s time to talk about grass seed. The good news is that fewer people will need to undertake this project as the milder summer has helped keep area lawns alive. There are many steps to success when overseeding, but one of the most important is choosing quality seed.

Many people have the idea that all grass seed is basically the same. Big mistake! If you don’t know what to look for, you may be introducing unwanted intruders into that new stand. In particular, we are concerned with seed contaminated with orchardgrass and/or rough bluegrass (also known by its Latin name, Poa trivialis, or Poa triv for short). These are both perennial grassy weeds that cannot be selectively controlled once they are in a lawn. Orchardgrass is a problem because it is faster growing and lighter green than our turfgrasses. It is a bunch grass so it doesn’t spread, but infested areas are still unsightly due to small tufts of this species in the lawn. Rough bluegrass is fine-textured and forms circular patches in the lawn. It blends in fairly well until summertime heat causes it to turn brown rapidly. If the rough bluegrass would just die in the heat, it would only be a temporary problem. Unfortunately, it usually just goes dormant, turning green again with cooler temperatures and rain.

Buying quality seed starts with knowing how to decipher the seed label. One of the most important things to look for is listed as “% other crop.” “Other crop” refers to any species that is intentionally grown for some purpose. That would include turfgrasses (those species other than the one you are buying) and pasture grasses. Orchardgrass and rough bluegrass both are listed as “other crop” seed.

Seed labels are required by law to show the percentage (by weight) of “other crop” in the bag, but unless a species constitutes 5% or more, the label doesn’t have to list each species by name. How much “other crop” is too much? That’s a difficult question to answer, but the tolerance is very low. It depends on what the “other crop” actually is, and the quality expectations of the buyer. In practice, “other crop” may refer to something relatively harmless, like a small amount of perennial ryegrass in a bag of tall fescue, or it may refer to something bad, like rough bluegrass or orchardgrass. The homeowner really has no easy way of knowing what the “other crop” is, although there are some hints.

If it is something bad, less than one-half of 1% can ruin a bag of seed. For example, if a bag of tall fescue seed contained 0.5% orchardgrass, the buyer would end up “planting” 12 to 16 orchardgrass seeds per square foot! Similarly, planting Kentucky bluegrass seed containing 0.5% rough bluegrass would result in about 25 to 35 rough bluegrass seeds per square foot of lawn. Obviously, if your expectations are high for the area you are planting, you would want the “other crop” to be as close to zero as possible. Good quality seed will often have 0.01% “other crop” or less.

Here is another tip to help ensure you purchase quality grass seed, as oftentimes inexpensive mixes are laced with other turf species. A good example is, many times bluegrass or tall fescue will have perennial rye in the bag. Rye germinates quickly but does not stick around under harsh summers. The take home message is if you are buying bluegrass buy all bluegrass; there is no need for filler seeds. Same is true for tall fescue, buy tall fescue not rye grass, or some other fluff.

When it comes to grass seed you get what you pay for so buyer beware. Read the label and always purchase from a reputable garden center and avoid most bagged seed mixes sold for a regional or national market.


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