Saving Seed

There’s nothing like a cold winter day to get you thinking about spring. So last weekend when it was 2 below zero (still zone 6, see previous blog entry) I did a seed inventory. I was about to start filling out an order from my favorite catalog when I realized that I still had a lot of left-over seed. So I sorted and evaluated my stock. Wow! Do I ever have a lot of lettuce seed! Some of it from 2005.

The question is: will that seed still germinate? It depends on the species and the storage conditions. In the case of lettuce, my references say it is one of the best at remaining viable… maybe 5 years under good conditions. My left over onion seed from 2003 on the other hand, is mostly dead.

What are good storage conditions? In a nut shell, cool, dry and dark. About 40 degrees F and very low humidity. Temperatures in your fridge are fine; the enemy is moisture. Sealing dry seed in air tight jars with silica gel packets or another moisture absorbing material is best. Dry powdered milk might be handier for many of us than silca gel. Just put a couple of tablespoons in tissue paper, seal with rubber bands and add to your airtight seed storage jar.

Is that how I store my seeds? Sadly, not. They’ve just been in the garage… dry but subject to a range of temperatures and fluctuating humidity. So I’ll lower my expectations. Experience tells me that for most species, germination percentage may be down but enough of the seed is viable enough to warrant keeping it. Just sow a bit thicker than with fresh seed. If I had the time (or if the stakes were higher)I’d do a germination test by putting seed on moist paper towels at room temperature and recording the percentage that sprout. I probably won’t get around to that either.

Ok, here’s what the books say about seed longevity under good storage conditions. 1 year : onion, parsley, parsnip. 2 years: okra, pepper sweet corn. 3 years: bean, carrot, pea, broccoli, spinach. 4 years: beet, cabbage, cauliflower, eggplant, pumpkin, tomato. 5 years: collards, cukes, melons, lettuce, radish.

Note that what happens is that germination percentage declines over time. They don’t all die at once. And storage conditions have a big effect. One reference I read described seed of many vegetable species with germination rates over 50 % many decades after being put into ideal storage.