Old Seed: To Sow or Not to Sow
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
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.
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
If in Doubt, Test!
A simple germination test will help you determine whether your
seed is worth planting.