The short version: How long seeds last depends on the type and on how they are stored. Most home garden seed stays usable for about one to five years when kept cool, dark, dry and airtight, ideally in a sealed jar in the fridge with a desiccant and a dated label. Short-lived seed such as onion, leek and parsnip often fades within one to two years, while lettuce and cucumber can keep for five years or more. If an older packet has you guessing, a quick damp paper towel test gives a rough germination rate before you sow.
A packet of seed is a living thing, just resting. Given the right conditions it waits patiently, and given the wrong ones it slowly loses the spark that lets it sprout. Knowing roughly how long different seeds keep takes the guesswork out of that tin of half-used packets, where storage often matters as much as age.
How long do seeds last by type
Most vegetable seed lasts somewhere between one and five years when stored well, and the type is often as big a factor as the conditions. Some families are naturally short-lived while others keep for years, so it helps to know which is which.
- Short-lived (about one to two years): onion, leek, spring onion, parsnip, sweet corn and parsley.
- Medium-lived (about three to four years): carrot, bean, pea, beetroot, celery, capsicum, chilli, pumpkin, tomato and the brassicas such as broccoli and cabbage.
- Longer-lived (about five years or more): lettuce, cucumber, kale, radish and rocket.
Short-lived types are worth buying fresh and using within a season or two, since they lose vigour quickly even in good storage. Onion seed is the classic culprit, full of promise one year and stubbornly patchy the next. The longer-lived ones, kept cool and dry, can surprise you long after you expected them to give up.
These are general guides, not guarantees, since actual life depends on how the seed was dried and stored. Treat the ranges as a starting point, and test anything you are unsure about.
Why warmth and moisture shorten seed life
Heat and moisture are the two main things that age seed quickly, because both nudge a resting seed towards using up its stored energy. Kept warm and damp, a seed respires faster and breaks down rather than waiting quietly to be sown.
Lower the temperature and the moisture, and you slow that clock right down. As a rough guide, every few degrees cooler and every drop in humidity helps seed hold its vigour for longer. That is why a sunny windowsill, a hot tin shed or a steamy kitchen cupboard are among the worst places to keep a packet, however handy they feel.
How to store seeds so they last
The best way to store seed is cool, dark, dry and airtight, which keeps the metabolism low and the moisture out. Those four conditions do most of the work.
Make sure the seed is fully dry before it goes away, since trapped moisture invites mould. Then seal it in an airtight container, such as a screw-top jar or a zip-lock bag. A small silica gel sachet, or even a spoon of dried rice, tucked inside keeps the air dry, and spent sachets can be dried in a low oven and reused.
The fridge suits a sealed seed container in most Australian climates, since it is cool and steady. This matters more in the humid summers of Brisbane, Cairns and Darwin than in a dry Perth or Adelaide cupboard, but an airtight container is wise everywhere. Let a jar come back to room temperature before you open it, or moisture will bead on the cold seed the moment the lid lifts.
Wherever you keep them, label each jar with the variety and the date, which tells you at a glance how old the seed is. When it is time to top up the short-lived lines, you can browse our vegetable seeds for a fresh start.
How to test if seeds are still viable
The simplest way to check old seed is a damp paper towel germination test, which gives a rough viability rate before you commit a whole bed. It takes a few days and a handful of seeds, and it spares you a patchy row weeks down the track.
Lay ten seeds on a piece of moist, not soaking, paper towel. Fold it over them, slide it into a sealed bag to hold the humidity, and keep it somewhere warm and out of direct sun. The top of the fridge is a fair spot.
Check it after the number of days that crop usually takes to germinate, keeping the towel damp throughout. Count how many seeds have sprouted, then multiply by ten for a rough germination rate. Six of ten means about 60 per cent.
Use that figure to decide what to do next. A high rate, above about 75 per cent, means sow as normal. A low rate is not always a write-off, since you can sow more thickly to make up for the gaps. Very low or no germination is your cue to start fresh rather than waste a bed.
Reading the date on a seed packet
Most seed packets carry a date, usually a packed-on or test date showing when the seed was packaged or last checked for germination. That is more useful than a best-before alone, because it tells you where the seed started.
Seed does not expire sharply on a given day, so treat the printed date as a guide to likely vigour, not a hard switch. A packet just past its date is often still worth a quick test rather than the bin. If you are raising those tested seeds undercover, our guide to starting seeds indoors takes it from there.
Frequently asked questions
How long do seeds last if stored properly?
Stored cool, dark, dry and airtight, most vegetable seed lasts about one to five years depending on the type. Onion and parsnip often manage only one to two years, while lettuce and cucumber can keep for five years or more.
Can you use seeds that are out of date?
Often yes. Seed does not expire sharply on the printed date, and many packets stay usable well beyond it if kept cool and dry. Run a quick damp paper towel test on older seed before sowing a whole bed.
What is the best way to store seeds at home?
Keep them cool, dark, dry and airtight. A sealed jar or zip-lock bag with a silica gel sachet, stored in the fridge, suits most Australian climates. Make sure the seed is dry first, and label each one with the variety and the date.
How do you test if seeds are still good?
Use the damp paper towel test. Place ten seeds on moist paper towel, seal it in a bag somewhere warm, and check after the days that crop usually needs to germinate. Count how many sprout and multiply by ten.
Do seeds need to be kept in the fridge?
The fridge is not essential, but it helps, since it is cool and stable. The real key is an airtight container so moisture cannot get in. A cool, dark cupboard away from heat works too, as long as the seed stays dry.
Storing seed well is a small habit that pays off every time you reach for a packet and sow it with confidence. Keep it cool, dark, dry and airtight, label it with the date, and let a quick test settle any doubts.
Related growing guides
- How deep to sow seeds
- A step by step guide to starting seeds indoors
- 21 reasons your seeds did not germinate
Ready to plant? Browse our Vegetable Seeds.