If you want to store seeds for an extended period, ie beyond their normal life then you can freeze them in a zip locked bag. However most people won’t need to do that, the normal objective - which I discuss here - is just to save seeds for long enough to use up the seeds they have purchased.
Seeds will last their advertised package life when:
Once you open a seed packet, expect seed life to reduce a little, unless you store your seeds in a sealed container of some sort.
I store my seeds in a wardrobe in a bedroom that we try and keep cool, although in summer cool cab be 20+ degrees and in winter 16-18c. The wardrobe is dark, dry, and fairly temperature stable. We generally find that seeds store well in there. I don’t store my seeds in a sealed box, I store them in wicker baskets.
I have a lot of seeds and I need a way to keep track of them. Since I already have a database to manage all aspects of my gardening and publish data for this book and my newsletter, I’ve extended it to manage my seeds too.
The seed packet database, just allocates a unique number for each packet and allows me to pick the supplier/variety and record the number of seeds and their expiry. It takes a few seconds to log a packet.
You can read and watch videos about this database, in this chapter of my ebook.
Here’s a video of the seed packet database, although I’ve slightly simplified it now.
As previously mentioned, how long seeds will last depends to some extent on the environmental conditions they are exposed to. However they also vary considerably based on the type of seeds. As seeds age they accumulate damage, this reduces their viability, ie whether they will germinate or not, but also their vigour. It’s the vigour that matters most to me. Often older seeds will germinate, but the resulting plants won’t thrive.