Do Seeds Expire? How Long Do Seeds Last | Shido

The answer is: it depends on whether oxygen got there first.

A seed is a living organism in a state of suspended ambition. It has everything it needs to become a plant — genetic instructions, stored energy, the biological equivalent of a very detailed to-do list — and it is simply waiting for the right conditions to begin. Oxygen is what ends that wait prematurely. It degrades cell membranes, depletes stored energy reserves, and reduces germination rates long before the packet shows any outward sign of failure. The packet looks fine. The seed inside has made its peace with the situation.

Standard paper-packed seeds begin losing germination viability after approximately one year. Not because they are poorly made. Not because the company that sold them does not care. Because paper breathes, and oxygen is patient, and a seed stored in a paper packet is essentially doing a slow negotiation with entropy that entropy always wins.

What actually happens to a seed that has been sitting in your drawer

Here is the thing nobody puts on the packet: a seed that has degraded does not simply fail to sprout. It may still sprout. That is the problem.

A degraded seed can produce a seedling — it just produces a weaker one. Compromised root development. Reduced disease resistance. Lower tolerance for transplant stress. A plant that germinates from a seed stored at full vigor is measurably more robust than one that germinates from a seed that spent eighteen months slowly oxidizing next to a dried basil packet you got free with a magazine subscription.

This is the two-part claim that matters and that nobody in the seed industry talks about because it requires admitting that most of what they sell is already past its best before it reaches you.

Part one: vacuum sealing produces a better germination rate. More seeds actually sprout.

Part two: vacuum sealing produces stronger plants. The seeds that do sprout have not already spent their energy reserves surviving the packaging process.

Shido seeds are hermetically vacuum-sealed before the Japanese woodblock artwork goes on. Oxygen removed entirely. State law requires a 3-year viability date on sealed packaging, which is the legal minimum and not a suggestion to throw them away at the three-year mark. NASA research on hermetic seed storage suggests viability up to ten years in cool, dry conditions. The packet you buy today is, in the most literal sense, still viable when your eldest child starts secondary school.

How long do seeds last: a variety-by-variety reality check

Not all seeds age at the same rate, which is either reassuring or distressing depending on which ones you have in the drawer.

Short-lived seeds — one to two years in standard storage, sometimes less

Onion and leek seeds are notoriously impatient. They lose viability faster than almost anything else in the vegetable garden, which is unfortunate because onions take forever to grow and you really want the seeds to be working at full capacity when you finally commit. Parsnip is similarly unreliable past year one. Among flowers: delphinium, larkspur, and salvia. These are the varieties where the difference between paper and vacuum sealing is most pronounced, and where most gardeners discover the problem at the germination stage when it is too late to do anything about it except swear quietly and order more seeds.

Medium-lived seeds — three to five years under good conditions

Most vegetables fall here. Carrot, beet, broccoli, kale, spinach, and the majority of the brassica family hold reasonably well. Most common herb seeds — basil, dill, cilantro — sit in this range. Among flowers, cosmos, marigold, zinnia, and sunflower are the reliable middle ground. These are the seeds most people think are fine when they find them three years later. Sometimes they are. Often the germination rate has dropped from ninety percent to fifty, which means instead of a garden you get a suggestion of one.

Long-lived seeds — five to ten years in proper storage

Tomato seeds are remarkable. Stored correctly, they regularly germinate at high rates past five years, and there are documented cases of viable tomato seeds at ten years and beyond. Cucumber and squash family seeds hold similarly well. Among flowers, hollyhock seeds have impressive longevity. These are the varieties where vacuum sealing is perhaps less immediately critical — but still meaningfully extends what is already a good baseline.

The practical implication is that the variety matters, and so does the storage method, and the combination of a short-lived variety in a paper packet stored in a warm kitchen drawer is essentially a compost subscription that costs the same as a functional seed packet.

How to store seeds long term if you have already opened the packet

A vacuum-sealed Shido packet that has been opened is no longer vacuum-sealed, which is both obvious and worth stating because people occasionally ask. Once oxygen re-enters, the degradation timeline resets to roughly the same as a standard paper packet — viability begins declining within the first year.

The practical approach for opened packets:

• An airtight glass jar works significantly better than the original paper packet for ongoing storage.
• Add a small silica gel packet to manage humidity — seeds need to stay dry, and the enemy after oxygen is moisture.
• Store the jar somewhere cool and dark. A consistent temperature below 50°F slows metabolic activity in the seed substantially.
• A cool pantry shelf is better than a warm kitchen drawer. A dedicated corner of the refrigerator is better than the pantry shelf, provided the seeds are completely dry before they go in — moisture and cold together rupture cell walls, which is a specific kind of horticultural disappointment that feels personal.
• Label everything with the date opened. Not the original viability date on the packet. The date you opened it. The original viability date is now irrelevant. You are running a new clock.

Shido packets are sized to encourage planting the full contents in one season. This is both the correct horticultural practice and a reasonable way to avoid the entire jar-and-silica-gel situation, which, while effective, is the kind of system that begins with good intentions and ends with fourteen labeled jars in the back of the refrigerator that your partner asks about every six months.

What the germination test actually tells you

If you find a packet and cannot determine how old it is — because the drawer has eaten the label, or you acquired it from someone whose relationship with record-keeping was optimistic — the damp paper towel test is the most direct answer available.

Place ten seeds on a moist paper towel. Fold the towel over the seeds. Put it somewhere warm — a spot that stays around 65 to 70°F. Check it after the number of days listed for that variety's germination window. Count what sprouted.

Shido seeds are germination-tested at independent third-party labs before the Japanese woodblock artwork goes on the packet. The rate is confirmed before you receive it. You are not running the paper towel test to find out if the seeds are good. You are running it to find out what percentage of the garden is going to happen as planned versus as a surprise.

The honest summary

Seeds do not expire the way milk expires — dramatically, with evidence, and in a way that makes the decision obvious. They expire the way enthusiasm expires: gradually, partially, and with enough residual activity to make you think everything is probably fine until the moment it clearly isn't.

Paper packets are not storing seeds. They are composting them at a pace that feels respectful but is not.

Vacuum sealing removes the oxygen. That is the intervention. Everything else — the NASA research, the state law viability date, the third-party lab testing — is the evidence that the intervention works. Chive has sold Shido seeds at the RHS Chelsea Flower Show for fourteen consecutive years. The people who buy seeds at Chelsea are not casual gardeners making optimistic purchases. They know what germination rate means. They come back because the seeds work.

Your Shido packet is sealed. It is waiting. It has no particular opinion about when you get around to planting it.

That is the correct attitude for a seed to have.