Gardeners tend to have foibles. You know the definition of a foible? According to Webster’s Dictionary it’s “a minor flaw, weakness or failing.” One of those foibles is our inability to throw things out. From used pots and trays to broken tools, malfunctioning sprinklers and bent tomato towers that could be modern art…someday, many of us are “frugal.”
Seeds are another item we like to save. Seeds can stay viable for only a certain number of years, depending on the variety. Some are quite short-lived. Parsnip seed never lasts for more than one growing season, and spinach and allium (onions, leeks etc.) seeds rarely germinate the second year.
The amount of oil in a seed determines how long it will remain viable. Higher oil content seeds deteriorate more rapidly.
Humidity also plays a large role in seed storage. We are fortunate in the Okanagan because drier environments favour longer seed life. Seed is best stored at about 5-7 deg. C and at 50% humidity. Store packets in a sealed jar with a dessicant (to absorb moisture) like powdered milk or rice at the bottom. Put the jar in your fridge or in a cool basement area.
You can easily test seed which has been leftover by taking ten seeds from the package and laying them out on a damp towel at an equal distance apart. Roll up the towel and place it in a plastic bag. Leave the bag in a warm (room temperature) location for a few days. Light levels don’t matter.
After a few days unroll the paper towel and see how many seeds have germinated. The percentage of germination will most likely be echoed in the garden when you plant.
Below are the average life spans of common vegetable and flower seeds with no special care given. Storing them cool and dry will increase these times, perhaps by a year or two. Before you become curator of a seed museum, however, you might want to consider buying less or sharing seeds with a friend or neighbour.
Bush and pole beans-3 years
Broccoli, Brussel sprouts, cabbage, cauliflower and kohlrabi-3 to 5 years
Collard, Kale-3 to 5 years
Sweet Corn-2 years
Leeks, onions-2 years
Oriental greens-3 years
Swiss Chard-2 years
Flower Seed-annuals-1 to 3 years perennials-2 to 4 years