Customers often ask how long grass seed will keep for. Providing you store seed in cool dry conditions, it's actually longer than you might think. Grass seed, like most natural products does eventually have a best before date. We suggest that you should use your seed within 2 years of purchase. Every bag is sealed closed using a DEFRA label. This label contains all the certification details for the seed mixture, but also a month and year of sealing, this saves a lot of trawling through emails to remember when you purchased your grass seed.