Seed Storage – How Long Do Seeds Last?

The importance of seed storage quickly becomes clear to anyone who gardens for more than a year or two. A single seed packet often contains more seeds than anyone needs in a single year, and if you harvest seeds at the end of the growing season, you’ll usually be left with even more that need to be stored for future use.

Unfortunately, seeds don’t last forever, and seeds that aren’t kept in the right storage conditions will often disappoint by failing to germinate reliably once they’re sown. Here’s what you need to know about keeping your seeds healthy and viable for as long as possible.

All seeds will slowly deteriorate in quality as the years pass, and their germination rates will fall until the seeds are essentially lifeless. The length of time this takes varies according to the plant’s species. Virtually all seeds are good for the first year, and most for the second, but then the viability can drop off dramatically.

For example, peppers are rarely successful past their second year of storage. Tomatoes and peas can often last for four or five years without problems, while lettuces and most brassicas can last even longer.

If you’ve bought your seeds, the packet will usually have a sow-by date to give you an idea of how long you can store them. If you’ve harvested your own, then a search online should give you a rough idea of how long they’ll last.

But in any case, there’s no harm in sowing old seeds. The germination rates will be lower – or even zero – but any resulting plants will still be perfectly healthy and productive. All it’ll cost is a little time for sowing and the potential disappointment of germination failure.

But whichever species of seed you’re dealing with, providing the right storage conditions is vital for keeping them healthy and viable. Badly stored seeds might not even be successful in their first year, and will certainly struggle to germinate in later years. Here are the key points to bear in mind when storing seeds.

Seeds should be stored in cool, dark, and dry conditions. The salad drawer of a refrigerator is ideal, although a cupboard in a basement will also work well so long as the temperature is reliably below 50°F (10°C).

Your seed collection should ideally be stored in an airtight container, such as a preserving jar with a rubber seal or a zip lock freezer bag. This is especially important if the air may be humid.

For organization, keep each seed type in a separate, clearly labeled envelope. Relying on memory or visual identification of seeds will only invite confusion later on. Use our handy instructions to make your own seed envelopes, and mark them with the variety, date of storage, seed origin, and any other helpful notes.

And lastly, if you’re dealing with amounts of seed you know you won’t realistically sow within their viability period, giving them away to like-minded gardeners is a good way to use them up without waste.

If you’re unsure whether a certain batch of seeds is still viable, you can test the seeds before the start of the growing season, giving you a chance to buy replacements if necessary. Count out five to ten seeds and spread them apart on a moistened piece of tissue paper. Roll up the tissue, place it in a plastic bag, a or container, and keep it in a warm place.

Ensure the paper stays moist, and keep checking the seeds every two or three days. You should see the seeds start to sprout at around their typical germination time, and can measure the ratio of success to failure for the batch.

The beauty of this test is that you can spot germination quickly without waiting for seedlings to break through the soil. You can also do it long before the weather is suitable for outdoor growing, giving you plenty of time to work with if you need to find new seeds.

But no matter how old or young your seeds are, there are several easy ways to improve the speed and rate of germination. Read our Tips for Seed Germination article and you’ll find out how to put your growing season on a solid footing from the start.