How do I read a grass seed label?

Tuesday, April 5, 2011

There is a lot of valuable information on a Jonathan Green grass seed analysis label.  It is important to understand the label so you can make an educated decision on which Jonathan Green grass seed to buy.

By law, there are requirements for any grass seed or mixture of seed offered for sale to have a host of information on the seed label.  The first listing is the name of the seed if is a single variety, or a mixture name if more than one variety of grass seed is involved, like “Full Sun Grass Seed Mixture”.  There are headings for Pure Seed, Description, and Germination and perhaps a listing of where the seed originated listed as, Grown In.   

Seed is mixed as percentage by weight, which means that all of the ingredients have to add up to 100%.  If the first line reads 19.65% Perennial Ryegrass, that would mean that seed was 98.25% pure (20% x 98.25% = 19.65%).  The next line could be 19.60% Creeping Red Fescue and so on. 

Each component lists a germination percentage and good quality grass seed will have germination rates of 80% and higher.  Frequently Ryegrasses and Fescues have germination rates of 90% or higher.  Kentucky Bluegrasses are usually listed in the 80 to 90% germination range.  A germination percentage of 90% means that in a testing laboratory, under ideal conditions, 90 out of 100 seeds germinated after a 2-3 week period.  Each seed label also lists a “Tested” date indicating when the seed was tested in the laboratory for germination. 

Inert matter consists of anything that will not grow, soil particles, chaff or straw.  Inert mater will not be detrimental to your lawn; however, you want it to be as low as possible.  Quality seed will have inert matter listed at no more than 2.00%.

Crop seed is defined as anything that is grown by farmers for profit.  This could be oats, timothy, orchard grass, corn, radish, etc.  Crop seed should be as low as possible on the label, hopefully no more than 1.00%.  Usually crop seed can be controlled with normal maintenance and mowing and will go away if they are introduced into your lawn from a mixture.

Weed seed is just that, anything defined as a weed seed.  Again, you want to buy seed with as low weed seed content as possible, hopefully less than .10%.  Most weed seeds can be controlled by available lawn maintenance products and mowing. Undesirable grass seeds will be listed on the seed tag if they are present.  These include Johnson grass, annual bluegrass (poa annua), hairy chess and more.  These weeds are listed this way because they are hard to control and kill with traditional treatments.  They may require you to kill them in your lawn with a non-selective herbicide and re-seed your lawn if they become established.  It is best to avoid mixtures listing “undesirable grass seeds or prohibited noxious weeds”. 

When grasses have a variety name before the species it implies an improved variety.  An example would be, “Dakota” Tall Fescue.  Look for grass seed with variety names instead of common-type grasses for a better-looking lawn in the long run.

Finally, a lot number is assigned to each mixture for tracking purposes and the name and address of the company that mixed and bagged the seed is listed.  In the next few months I will discuss in detail the cool-season grass species, Kentucky Bluegrass, Ryegrass and Fescues.

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