Do seeds go off?

[vegswap]

Hi, I've been given some out of date seeds -some as long ago as 2002. I've been told that seeds last 20 years or more. Is this true? Is there any point planting my out of date seeds?

[pongeroon]

I think it depends on the type of seed. Carrots don't last very long before they become unviable, other things (er....can't think of an example) will last years.

[oldherbaceous]

Dear Vegswap, our dear Pongeroon is quite correct, some seeds last a lot longer than others, peas for example will last for years if stored correctly.
I have got a chart with the lenght of seed viability somewhere, but do you think i can find it, how come the one thing you want is, the one thing you can't find.

[AdeTheSpade]

Hi Vegswap
I've managed to find my info - it's in the form of a very old poem, but I'll spare you having to interpret the funny language and attempt to summarise it:
Parsnips probably only last one season;
Brassicas, eg broccoli, cauli, sprouts, cabbage and kale, last at least 3 years or more, and kohl rabi the same;
Turnips and swedes don't last too well, but may last a second year;
mustard and cress (!) lasts for 3 seasons, radish lasts 4;
Lettuce lasts for at least 3 or 4 years, same with beetroot and spinach;
Leeks last 3 years, and apparently carrots the same (although I haven't found that's the case, like pongeroon)
Marrows and cucumbers (so presumably other squashes as well) last 7 years, celery and celeriac 6;
All beans (runner, french, broad) not sure how to interpret this one! It says "broad beans, french ones, runnners, sown in May, each hath a sowing left before you throw away" so presumably that means 2 years rather than 2 sowings in one season;
Peas, parsley and salsify will last 2 years.

Don't know if that helps at all,

AdeTheSpade

[Urban Fox]

I'm pretty sure I read that they had managed to grow 2000 year old seeds found in the pyramids.

So, as long as your seed has been stored in a cool dry place - then it might be worth giving them a go.

you could try doing a germination test. Place some on kitchen towel and keep it damp and warm. Check regularly to see if any germinate - then you'll have your answer.

UrbanFox

[FelixLeiter]

What you've got to watch with seeds is how old they are to start with. That is, it's quite possible to buy seeds which are already several years old. Before they are packeted, by law seeds are germination tested and if they are within their defined viability (which differs according to crop) they can be packeted, given a date stamp which you see printed on all packets, again by law: "Packeted year ending blah de blah etc.", and sold. So, your bought seeds are good for the year they are date stamped for, because they've been tested and found to be fine, but they may already be quite old and by the second year, viability can plummet. So it's always a risk, but do your own germination testing, on a bit of damp towel, and see what happens. It's quite fun, and you can always prick out the resulting seedlings if you don't want to waste them.

[Johnboy]

Hi Felix,
Old seed may well germinate and are worth at least a trial but sometimes they will germinate but lack the capacity to grow properly. They do not have the vibrancy of new seeds.
The whole idea of growing is to get the best out of what ever you are trying to grow so if the old seed are slow to go beyond simply germinating then it is best to cast them aside and quickly resow with fresh seed.
JB.

[FelixLeiter]

That's a very good point, JohnBoy. The way I see it, though, old seed is self-selecting, with the most vital and vigorous emerging. For sure, though, you've got to do a bit of screening of the resulting seedlings, which is always good practice — anything that's a bit wan or off-colour should go straight on the compost.

[Johnboy]

Hi Felix,
To a degree you are right about self selection because they either germinate or they do not. Because they germinate doesn't mean that they have sufficient vigour so as you say if they do not seem to be performing properly then it is best to cull them.
Many people struggle will the culling of plants but surely you should only want to grow the best that you can provide for the normal restricted space that people have.
You should sow with the expectation of an 80% germination rate.
To me if you want 100 of something you should sow 136 and this will account for any slow or poor plants. If you are lucky and you germination rate is high then you have plants to swap or sell. You should always hold back taking any untoward action until you are sure that your plantings have got away to a good start. Then do what you will but not before.
JB.