The label on my bag of grass seed lists inert matter, other crop seed, and weed seed as minor ingredients. What is inert matter and why are other crop and weed seeds included in the mix?
David Balaban, Chardon, OH
John Fech, a horticulturist at the University of Nebraska in Omaha, responds: Reading a grass seed label is much like perusing the dietary label on packaged food items, noting the grams of fat and sodium, the calories, and the amounts of various vitamins. Federal law requires these ingredients to be listed. Similarly, most states have laws that require a detailed listing of the various ingredients in a bag of grass seed.
Of all the ingredients you mentioned, inert matter is the only one that is not necessarily objectionable. It simply means something that will not grow, like the grass stems or seed coverings.
Conversely, crop seed and weed seed are two ingredients to be leery of. Crop seed sounds like a good thing, but this ingredient is seldom turfgrass seed. Just about any plant species can be listed as crop seed, including bromegrass, timothy, and even bentgrass. If the seed mixture has even 1 or 2 percent of “crops” in it, your lawn could be filled with undesirable plants. The percentages of weed and crop seed listed on a label should be as low as possible, preferably well below 1 percent.
Other items to note on a grass seed label are the date the seed was harvested, the date it was tested for germination, and the germination percentage. Unlike some plants, grass will not grow well from seed that is more than a year old. And a germination rate lower than 90 percent is a poor buy.
As with most things in life, you get what you pay for. Think of high-quality seed as an investment rather than an expense. Resist the temptation to buy any old seed. Some hardware stores and garden centers put a very low price on old or low-quality seed and place it close to the cash register for a quick sale to customers who do not know any better.