As the growing season winds down, you may find you have more seeds than you quite know what to do with. Between exchanging seeds with friends and neighbors and taking advantage of end-of-season sales, it’s easy to amass a collection. Additionally, you may discover you haven’t even used all of the seeds in your own collection this year. How can you preserve them so they’ll grow well next spring? Here are a few tips.
Before You Store
In a perfect world, all seeds would sprout no matter what. However, some seeds have a better chance than others. Assess your seeds, one packet at a time, and toss any seeds that appear different from the others or otherwise damaged. There's no point in going through all the trouble to prep and store a seed that isn't capable of producing. Since most seeds often remain viable for up to three years, toss any that may be past their grow-by date. This includes seeds you may have purchased on a whim a decade ago and seeds you have the intention of growing each year, but can never find the space for them.
While it may seem obvious, you'd be surprised how many gardeners overlook these very basic questions. Before you begin the storage process, ask yourself do you, in fact, wish to grow those particular seeds the following year? Did the plant grow well or did it struggle? Did caring for the plant take up too much time and take more work than you'd originally expected? Did you eat or otherwise enjoy it? As gardeners, it’s easy to create a vast collection of seeds. Plants are precious and every seed is full of potential, so it's easy to get attached even when you have no realistic intention of growing them again. Set those seeds aside. If you’re active in a gardening community or have friends or neighbors who garden, consider trading with other gardeners for seeds you may enjoy growing more.
Proper storage begins with dry seeds
Make sure the seeds you plan to store are dry. Moisture can ruin your seeds and make them a gross, moldy mess! Remember, the longer you plan to store them, the drier they need to be. If you’re short on time, you can dry the seeds in a dehydrator or even oven as long as you keep the heat to 100 degrees Fahrenheit or less. To ensure your seeds are dry, try snapping some. If they bend rather than snap, they may need to be dried for longer.
As an added precaution to keep them absolutely moisture free in storage, add a packet of silica gel to your storage jar. If you don't have any saved silica packets around from spare shoe boxes and handbags, an easy alternative is a small cheesecloth bag filled with a tablespoon or two of powdered milk.
Choose the right storage container
It’s tempting to keep seeds in the packets they came in but this makes it easier for moisture to seep in, especially if you live in a wet or humid climate. They also make it easier for critters to nosh on your precious seeds for a mid-winter snack. Instead, screw-top Mason jars or glass containers with hinged lids will do the trick both reduce moisture and keep hungry rodents and pests away. Label the jar with a sticker or use a Sharpie to write the name of the seed and the date you’re storing it. That way, you’ll know exactly what’s in it.
You may also opt to store seeds in paper or mesh containers. Doing so is ideal if you’re unsure how dry your seeds are. If you think there may be some moisture remaining in the seed, these permeable containers help ensure any moisture can escape. However, you’ll still need to keep little pests from filching your seeds. Wrap the packets in wire to prevent them from causing too much damage.
Place them in the right spot
Store seeds in a cool, dark, and dry place. While a refrigerator provides the ideal environment, if you don’t have space, there are other great spots to store them, too. Try storing them in a root cellar, pantry, or even a simple closet in a cool part of your home, so long as the space remains dry and consistently cool. Aim to store them somewhere on the north side of your home to take advantage of the coolest temperatures.
How long will your seeds last?
What you're really trying to answer is here is how long will they last, assuming they're stored properly. Some seeds like beans, beets, celery, chard, cucumbers, lettuce, radishes, spinach, tomatoes, and peas can last for long periods on the scale of several years. Other seeds, like onions, corn, parsley, and pepper often don’t last as long as you’d like, even when the proper storage techniques are used. It's nothing you're doing wrong, but rather just a characteristic of the species. For instance, these shorter shelf life seeds can be stored reliably for a year or two, and while you won't suddenly see them turn to mold or dust beyond that window, what can happen is their germination rates dropping significantly.
What about freezing the seeds?
Freezing is indeed an option, and in the case of a few plants it may actually be the best option. For seeds such as carrots, onions, and leek freezing actually ensures they remain viable for longer than they would at room temperature or typically 'cool' space.