“Can I use last year’s seeds this year?”
and
“how long will my seeds last?”
Both frequently asked questions in almost all workshops but as with many areas of gardening, they’re queries that can’t be replied to with straightforward answers. Moisture content and storage conditions are the two main factors that govern seed viability and as everybody keeps their seeds in different containers and conditions, this will differ from house to shed.
Seed Storage
Seed experts recommend that seeds are stored in sealed containers in cool but not frozen environments (so not in a freezer). My wholesale seed suppliers have advised me that the best storage conditions are in a fridge (I have a shelf totally devoted to the Greenside Up seed collections). It’s also recommended that they’re stored in their original sealed packets (they can be folded once opened) or if not available, seeds should be stored in brown envelopes (which draws moisture away from them).
Advice also given is that seeds generally remain viable for two years from packing, apart from parsnips which should be used within one year. However, it is possible your seeds will last longer (and from my own experience I know most do).
The following is a list that was published in Amateur Gardening that offered for popular vegetable and flower seeds:
Veg and flower seeds and how long they are at their best:
| Veg seed | No of years | Flower seed | No of years |
| Asparagus | 3 | Ageratum | 4 |
| Aubergine | 5 | Amaranthus | 4-5 |
| Beans | 3 | Anthemis | 2 |
| Beetroot | 4 | Anthirrhium | 3-4 |
| Broccoli | 5 | Calendula | 5-6 |
| Brussels sprouts | 5 | Celosia | 4 |
| Cabbage | 4-5 | Cineraria | 3-4 |
| Carrot | 3-4 | Clarkia | 2-3 |
| Cauliflower | 4-5 | Cosmos | 3-4 |
| Celeriac | 5 | Digitalis | 2 |
| Celery | 5-6 | Eschscholzia | 3 |
| Chicory | 5 | Gaillardia | 2-3 |
| Chinese cabbage | 5 | Godetia | 3 |
| Cucumber | 5-6 | Helianthus | 2-3 |
| Endive | 3-4 | Heliotrope | 1-2 |
| Fennel | 4 | Hollyhock | 2-3 |
| Kale | 5 | Impatiens | 2 |
| Kohl rabi | 5 | Larkspur | 1-2 |
| Leek | 3 | Linaria | 3 |
| Lettuce | 4-5 | Linum | 1-2 |
| Marrow | 5-6 | Lobelia | 4 |
| Melon | 5 | Marigold | 2-3 |
| Onion | 1-2 | Mesembryanthemum | 3-4 |
| Parsley | 2-3 | Myosotis | 2 |
| Parsnip | 1-2 | Nasturtium | 5-7 |
| Pea | 3 | Nicotiana | 4-5 |
| Pepper | 4 | Nigella | 2 |
| Pumpkin | 4 | Pansy | 2 |
| Radish | 5 | Petunia | 2-3 |
| Salsify | 2 | Phlox | 2 |
| Scorzonera | 2 | Salvia | 1 |
| Seakale | 1-2 | Schizanthus | 4-5 |
| Spinach | 5 | Sweet peas | 2-3 |
| Sweetcorn | 1-2 | Sweet William | 2 |
| Tomato | 4 | Viola | 1 |
| Turnip | 5 | Wallflower | 4-5 |
| Watercress | 5 | Zinnia | 5-6 |
Germination Test
If you’re unsure whether your seeds are viable it’s quite easy to check by doing a germination test (and now would be a great time to do it before you go ahead and order more seeds).
Just place ten seeds in a row onto a sheet of damp kitchen paper. Carefully roll up and place them inside a clear plastic bag. Label and keep in a warm place. Check after a few days, then after a week to see if any of the seeds have germinated, ensuring the kitchen paper remains moist. Keep checking. If 8 out of 10 seeds have germinated then you’ll know you have an 80% chance of a decent packet of seeds. If only three germinate, order some new ones.
If you have the space, and aren’t overly worried about what will grow, just empty what you have into the soil and see what happens, you never know you could be in with a few surprises!
Ellis & Roberts 1980 via Kew Gardens
If you’re mathematically minded, it might surprise you (as it did me) that there’s an equation for predicting seed viability. This equation is from the Kew Royal Botanical Gardens website which explains in detail how to use it and others, and how they were configured.
Lastly if you’re looking for advice on how to choose vegetable seeds, here’s a blog post I wrote in 2010 giving some tips and advice.
11 Comments
Thanks Dee, that’s really useful. Timely too, as I’ve been going through my old seeds and there a lot of old ones in there. Definitely going to try the germination test before ordering more.
Great, hope it helps. Let me know how you get on! Think I’ll be ditching lots of mine this year as my own tin of precious seeds certainly wasn’t kept in the best of conditions, being used for demo purposes for much of the year.
[…] wrote a post a few weeks ago answering the often asked question “how long will my seeds last?” One of the prime considerations for seed longevity is how they’re stored. Seeds are living […]
Thanks Dee, this post was just in time:)
Laura, great to hear that and you’re welcome 🙂
[…] are great months for sorting through your seed tins, checking what seeds you have and what to buy. Here’s a post that will help you figure out what seeds are viable – and how long you can expect them to […]
Wow! I’m surprised at the length of time some seeds last! I need to start sorting through mine…. one of the many jobs on an every lengthening list of jobs!
Me too Margaret and suspect I might have to replace a few too 😮 Seed suppliers will fairly much always say two years to cover themselves but in reality, if they’ve been looked after well, seeds will last much longer.
[…] some are out of date. Don’t throw them away, they might still be viable. Click this link for details on how long some of the more popular flower and vegetable seeds last as well as how to do a simple germination test to check their […]
[…] in case you missed it, my post this week was about seeds and in particular, how long you can expect them to last in storage. You might find it helpful if […]
[…] this idea leaves you dubious, you could always try a quick germination test. Dee, from Greenside Up wrote a good post this week that includes instructions on testing germination. If you get a good result from her quick test, then stick with the seeds you’ve got and save […]