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Old Seed: To Sow or Not to Sow
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Can I get away with using last year’s seed in this year’s garden? This is the question gardeners everywhere ask themselves as they peruse catalogs and websites, shopping for varieties that will make their gardens shine.

 

Before risking the success of your garden on seed that may of may not be viable, ask yourself these questions:

How old is your seed?

Check the seed packet for the “packed for” year. Certain crops, including onions, leeks, and parsnips, retain good germination rates for just one to two years, so it’s wise to buy new seed every year. Others, such as cucumbers and cantaloupes, can be successfully saved for five years or more, assuming you store them properly. Consult the chart below, reprinted from Colorado State University Extension, for relative longevity of common vegetable seeds under good storage conditions. If in doubt, test for germination (see below).

Did the storage temperature exceed 80°F? Was the humidity of the storage area high?

Studies show that the optimum seed storage temperature is 40-50°F. Storing seed at normal house temperatures, however, is not necessarily calamitous. In fact, just the opposite: Your home, assuming it’s not overly humid, is probably your best option for short-term storage. Keeping seeds in a space where both temps and humidity are high, or where there are wild fluctuations of temperature and/or humidity, will likely lead to disappointment when you plant them in your garden.

The Organic Seed Alliance (link to http://www.seedalliance.org/) offers this formula to help determine the range of good seed storage conditions:

The Sum of Temperature (°F) + Relative Humidity (%) should = less than 100

To put this in the context of our own comfort zone, 30-50% relative humidity is a comfortable level for indoor living. Therefore, storing seed in a cool spot (60°F or cooler) in your house is a better choice than storing it in the chilly temps (40-45°F) but high humidity of the average refrigerator. If you choose to store seeds in the refrigerator or freezer, package them in a moisture-proof container.

Whatever the temperature, relative humidity levels of greater than 75% will affect both the percentage of seeds that will germinate and the time it takes them to sprout.

Were the seeds protected from pests?

Store seeds in pest-proof tubs, jars, or tins to prevent insects and rodents from consuming them.

Were the seeds stored in the freezer?

Seed banks store their seed supplies at zero or sub-zero temps with the intention of preserving varieties for the future. You can do likewise, but remember to package seeds in moisture-proof wrapping, such as a ziplock-type freezer bag. Though freezing can increase longevity, long-term storage is generally not a gardener’s priority.

If in Doubt, Test!

A simple germination test will help you determine whether your seed is worth planting.