Why I love out-of-date seeds

The gardening question which never seems to have an answer is "how long do seeds keep?" The reason it has no answer is that there are so many variables ... how the seeds were harvested, processed and stored, what type of plant it is and probably also an element of luck. Tomato seeds keep longer than carrot seeds, for example, but there are no hard and fast rules. You just have to try them.

Take the little beauty in the picture above, photographed last month ... a very rare dark pink Estonian potato-leaf tomato called Siniy. This one came as a freebie from Association Kokopelli as part of their giveaway of out-of-date seeds. I've photographed the seed packet beside it so you can see the date on it: 1998. That's right, this healthy little tomato plant grew from seed which had been sitting in an envelope for 10 years.

Admittedly germination is no longer 100%. I sowed three seeds and only one germinated. But that's enough to give me a whole new generation of seeds if this plant survives to maturity. Tomatoes are naturally inbreeding, so saving seed from a single plant (although not ideal) is not a problem.

I'm not necessarily recommending out-of-date seeds as being better than, or even as good as, fresh seed. Old seed often has sporadic or very slow germination, and sometimes the plants which do grow are a bit weak and wobbly. But there are many good reasons to keep hold of those old packets.

There's not always much point going to the trouble of rescuing old seeds when you can just go out and buy new ones, but I often find myself needing to make the effort. Sometimes I get hold of old seeds of rare varieties which can't easily be replaced. Very often I get seeds in small quantities so I can't afford to waste any.

This is one of the very few areas where I disagree with Monty Don, who advocates throwing away any seed packets more than a year old and buying fresh ones. His reasoning is that fresh seed germinates quickly and grows rapidly ... which is true enough. Except that the whole idea of "new" seed being "fresh" is a bit of a myth.

Association Kokopelli have a policy of labelling their seeds with the year they were grown, but that's unusual. "Sow by" dates on commercial seed packets are sometimes arbitrary and meaningless. Patrick at Bifurcated Carrots wrote a very informative post about this a little while ago. When it says "packeted in year ended ..." that's exactly what it means – packeted. What year it was actually grown is another matter. As Patrick explains, the seed is likely to have been produced in a single batch in one year and sold as required. A germination test is done and if the seed passes the test then it gets packeted up and sold. The "sow by" date is based on the validity of the germination test and is not necessarily an accurate indication of the freshness or shelf-life of the seed.

And naturally seed companies are in no hurry to correct the common misconception that out-of-date seed is unviable, and that you need to go out and buy another lot.

In the UK and Europe, where dunderheaded legal restrictions govern the availability of vegetable seeds, readily available varieties often get dropped from the Common Catalogue and when that happens they can become very rare very quickly. The Heritage Seed Library keeps an eye on "deletions" and steps in to rescue them as necessary, but things can slip through the net. In other words, it's possible that the crumpled seed packet you've had languishing at the bottom of your seed tin for years may now be an endangered variety.

Another good point is raised by Soren of In The Toad's Garden. If you save your own seed, there is often a risk that a crop might accidentally cross-pollinate with another variety. Not that that's always a bad thing ... it's potentially the start of an exciting new variety. But if you're growing heritage varieties and need to keep the variety pure it can be a disaster. Soren keeps a few generations of seed for each variety, so when an accidental cross happens he can just go back to his seedbox and start again with seed from a couple of generations earlier, before the cross happened.

Tomato seeds are especially good to save long term, as they really do last for years. I'm still getting 100% germination from some seeds I scraped out of a Marks & Spencer's tomato onto a piece of kitchen roll in 2002. Back then I didn't know how to save tomato seeds properly so I didn't follow the usual recommended method and ferment them. But what the hell ... they still germinate.

Beyond the realm of vegetables, some seeds stay viable for very long periods. Last year, with a little expert care, some seeds from botanical specimens found tucked inside a book for 200 years were successfully germinated. And seeds of the common wild poppy are thought to remain viable for up to 100 years. The incredible display of poppies which bloomed on the First World War battlefields in the years immediately following the armistice was a mass germination of dormant seeds in the soil. Poppies are adapted as a cornfield weed and are sensitive to soil disturbance, so four years of pelting with mortar shells was just what they needed to trigger them off - generations of accumulated seed suddenly brought to life.

There have long been claims about peas found in Egyptian tombs still germinating after thousands of years - though personally I'm sceptical about that. It was a well publicised scam in Victorian times which seems to have kept resurfacing over the years.

Association Kokopelli sometimes give away packets of old seeds, and I have a lot of fun coaxing them into life. With such a large catalogue of varieties, they inevitably have a stock of unsold seeds which have passed their expected germination time. Rather than throw them away, they give them to gardeners to take pot luck with them. At the moment, for every five packets of seed you buy from their UK website you get a free packet of "old" seeds of the vegetable of your choice. Some don't germinate. But a lot of them do. The Siniy seeds shown above (and incidentally that seedling is now a fine healthy plant) was one of the packets I got free with Dominique Guillet's book a couple of years back. Other 8, 9 and 10-year-old tomato seeds I've had from Kokopelli are also germinating fine.

I also have a selection of old seeds from Association Kokopelli's pepper collection. Pepper seeds, in my experience, are not as long-lived as tomato seeds. Some of mine are five years old and not germinating. But the trouble with peppers is that they are very very slow to germinate, and need good warmth and moisture. It's not easy to keep them constantly warm and moist for a month or more, especially when moulds are likely to thrive in similar conditions. So here's what I've been doing to "resurrect" the slow-germinators.

An attempt to salvage some old seeds of Georgia Flame, a mildy hot pepper. The brown tint in the kitchen roll is tea! Using tea to assist pepper germination is a tip I picked up on the excellent Chileman website. (Sadly I haven't been able to germinate these.)

I cut a thin strip of kitchen roll (that's paper towels to American friends), fold it into a small square and wet it with warm water from a recently boiled kettle. A drop of tea is even better. Then I place the seeds within the folded square and put the whole thing inside a small sealable polythene seed bag. Making sure the seal is tight, I put it somewhere near a radiator and leave it for ages.

As you can see in the picture, the advantage of this method is that you don't have to keep opening the bag to see how the seeds are getting on. If you keep opening and resealing the bag, the contents will go mouldy in no time at all. But left sealed it should stay fresh for weeks. You check the seeds by holding the bag up to the light. Any sprouts emerging will be clearly visible. Once the sprouts emerge you will have to unseal the bag and plant them within a few days.

A Hungarian Semi-Hot pepper seed brought back from the dead after spending over a month on a bit of moist kitchen roll in a sealed bag. Nothing happened for a month, and then four germinated over the following couple of weeks. Not bad from what had appeared to be a packet of dead seeds.