The surrounding environment must be dark, cool and free of excessive humidity, such as an air-conditioned area. Other grasses, depending on the variety, typically last up to three years in storage. Germination chances are still reduced within the storage period.
Most grass seed I'm familiar with has a viability around 85% – meaning that if you. time, but seeds that are stored in a cool, dry place should last a long time.
I've kept some rare prairie grass seed for over 10 years in a ziplock – in a freezer.. is kept in a controlled humidity, cool environment they will be viable a lot long.. of grass you're talking about and the method and the length of storage you put