June 23rd, 2009
Gardening Tip: Storing Seeds
As a home gardener, your best tool for a strong, healthy garden is to start with high quality, vigorous seeds. New garden seeds from a reputable seed company usually have between an 80 and 100 percent successful germination rate. As your garden seeds age, particularly while sitting on the shelf in your hot garage, the seeds becomes weak and the germination rate starts to drop. Seeds that do germinate from weak seeds often create slow growing seedlings and less healthy plants.
Making Seeds Last
Fluctuating temperatures and humidity shorten a seed’s potential shelf-life. To ensure that seeds remain viable for as long as possible, keep them in a consistently cool, dry place.
Some gardeners go to the effort of drying their seeds to less than 8% moisture to ensure long-term storage (near ten years in cases). I take a more laid back approach and keep mine in an cracker jar in the fridge with a bit of silica gel to absorb moisture.
I purchased the silica gel from a local craft store (look in the floral aisle) for about $6. This type of silica gel has blue indicator crystals that turn pink when it’s time to change them out. You can reuse the crystals by baking them in the oven to release the moisture – the procedure is on the packaging.
Even under good conditions, seeds don’t maintain a high germination rate indefinitely. Here’s a rough guide on how long your seeds will last before losing vigor:
- Short Lived (one to two years):
Corn, Lettuce, Onions
- Medium Lived (three to four years):
Beans, Broccoli, Carrots, Peas, Spinach
- Long Lived (four to five years):
Cucumber, Radish, Pumpkin, Squash, Tomato, Watermelon
In a small garden, it’s not worth the risk of weak plants from planting seeds that have lost vigor. Unless it’s from a hard to find variety, I would discard seed that might be too old.
If you have more seeds than you expect to use before they die on the shelf, consider sharing them. I purchased far too many sweet corn seeds this season and will be sending them to The Dinner Garden, a San Antonio based non-profit group that distributes free seeds to gardeners, church groups, and food pantries who need them.
- Colorado State University Extension: Storing Vegetable and Flower Seeds
- Victory Horticultural Library – The Vegetable Garden, by MM. Vilmorin-Andrieux, 1885 – An extensive chart of expected seed shelf-life.