There have been tremendous advances in lawn seed technology over the past 7 to 10 years, resulting in many improved varieties that are more insect, disease and drought resistant available to the homeowner. Yet over half of the lawns in North America are over 7 years old.
Not all grass seed is the same, particularly when considering buying grass seed for the establishment of a permanent lawn.
The label is the best way to learn about a seed's quality. Every label is required by law to have an analysis panel to tell consumers exactly what's in the bag.
Rather than buying your next seed by the picture on the box, or the general advertising claims of the supplier, turn to the seed label on the back. There are a large number of new grass seed varieties available to the homeowner as single improved varieties, blends, and mixtures that provide a more environmentally sound lawn than just a few years ago. But you must have an understanding of the seed label to help you make a more informed buying decision.
In 1936 the Federal Seed Act mandated certain requirements appear on the seed label which must be followed by all seed packaging companies.
Name of seed variety: each kind (VARIETY) of lawn seed is listed by its percentage (PURITY by weight in the box or bag. Improved varieties have characteristics that are patentable under the Federal Plant Variety Protection (PVP Act. Thus, you should find specific trade names of varieties rather than the generic names: i.e. Kentucky bluegrass, perennial ryegrass, fine fescue. For example, Unique Kentucky bluegrass, Brightstar perennial ryegrass and Shademaster II creeping fescue are trade names.
Germination: the germination figure is an important percentage because it tells you how much of each pure seed variety listed will "sprout" and is capable of growing a grass plant. The higher the percentage, the better.
Inert matter: this is any substance in the container not capable of growth. Inert matter are empty hulls, sterile seeds, insect parts, etc. not discarded while processing. The lower the percentage of inert matter, the better.
Weed seed: any weed seed present is listed by percentage of weight. We really don't want any weed seeds in our seed container, but it is difficult and expensive to catch all weed seeds during the cleaning process. Acceptable limits range from 0.3 to 0.5% The higher the percentage of weed seed shown on the label, the poorer the quality you are buying.
Noxious weed: most states have listed weeds so troublesome and undesirable that their presence must be stated on the seed label. For a quality lawn, you want to avoid boxes or bags with noxious weeds listed. Your label should read: NONE FOUND.
There is other important information on the label that you should read and be aware of:
Name of the producer/distributor
Where each variety was grown
Lot number used for tracing the container through the marketing channels
When the seed lot was tested.
Many state laws require that a bag or box be retested and relabeled after 9 months to 1 year if not sold. You should check and be aware of the month and year the seed was tested.
There are many places where non-perennial annual grasses are beneficial to the environment, however this grass seed should not be purchased to establish or renovate a permanent lawn. Improved perennial varieties are your best buy for a permanent lawn.
Obviously, it is better to use the seeds for the season they were intended. However, if you have grass seed from previous years that you haven't used, it is still good to plant. The exception is that you can expect about 5% reduced germination each year past the packaged year. That of course depends on how the seed has been stored over the years.
With all the effort that goes into preparing a soil for planting, it may be a case of penny wise and pound foolish to use seed more than 2 years old.