Looking after valuable seeds

Once seed has been collected, we need to think of storage and viability. Humidity and temperature are the key factors in keeping them sound for next year’s crops. They’re best preserved in a cool, dry environment where temperature does not fluctuate.

I have some round film capsules from SLR camera days that provide a dry, sealed home until spring. In the absence of those, brown envelopes will do.

Assuming the seeds collected are viable, they should remain so until the following year. Beyond that, the percentage germination from each batch will decrease exponentially.

Rather like the food contents of our shopping bags, that have a “best before” date, there is a “sow by” date printed on seed packets.

As a general guide, given a suitable storage environment, most of the popular flower and vegetable seeds can remain viable for two to five years depending on the type.

This said, the seed firms are rightly, more cautious in stating the anticipated “shelf life” with an acceptable germination percentage in mind.

If you discover an unopened packet of seed several years out of date, run a simple germination test rather than waste time and effort in sowing.

Prepare a soaked paper towel on a saucer, place ten seeds on it and leave for two weeks in a warm, dark place. Be guided by the result.

Stored in ideal conditions, onion, leek, carrot, sweet corn, pea and bean seed should remain viable for three years.

Most brassicas, beet, celery, lettuce, turnip, cucumber and pumpkin remain sound for at least five years, occasionally ten or more.

And amongst the common or garden flowering plants it’s poppy, nasturtium, calendula, hollyhock and antirrhinum seeds that lead the field in longevity.