FAQ: How long does flaxseed keep?
If you buy whole flaxseed, don't be afraid to keep a jar of it handy on your kitchen counter. Whole flaxseed is naturally wrapped in a perfect package — a hard seed coat that preserves its goodness for up to a year or longer. If you grind flaxseed yourself (for example in a coffee grinder), it is best stored refrigerated in an opaque container and will keep for at least 90 days. Because ground flaxseed flows readily even when frozen, many users choose to store ground flaxseed in the freezer for even longer shelf life.
Also good quality milled flaxseed may be purchased, but attention should be paid to the manufacturers recommendation as to storage conditions. Overall the storage of milled flax is similar to other whole grain flour or raw nuts. Roasted flaxseed should also be refrigerated or frozen. Flaxseed oil should be refrigerated and usually has an expiration date about four months after pressing.