Seed Viability: Will It Grow?
Starting plants from seeds is fun and rewarding. There are many benefits of growing plants from seed including access to varieties that aren’t available as transplants, growing plants from seed is less expensive than purchasing transplants, and it’s a joy to be part of the miracle of watching a tiny sprout grow, flower and fruit. There are many reputable seed companies that produce quality seed, but even so, some varieties aren’t available commercially and the only way to obtain them is as a gift from a friend (or a seed exchange).
Most seed packets contain more seeds than are needed for a season. Seed can be stored for use the following season, and with proper handling most seed can be kept in good condition for a year or more. Leave seeds in the original packet (or transfer to paper envelopes), fold over the open end and seal with tape. Several sealed packets can be stored in a jar with an airtight lid (include a packet of desiccant). The jar can then be stored in a cool, dry place, away from drafts and sunlight, preferably at temperatures between 40-50 degrees (the refrigerator is fine but avoid freezer storage).
Even if stored under proper conditions, seeds vary in how long they remain viable (able to germinate and develop into a plant given the appropriate growing conditions). For instance, the general viability of lettuce seeds is one year, while the general viability of bluebonnet seeds is 20 years. Of course, when dealing with living things (which seeds are), there are always exceptions.
There’s a lot of information on a seed packet, but when it comes to viability, an important piece of information is the “packed for” date. There’s a good chance that the seeds in the packet will germinate if they are planted within this date. But what about that favorite that you’ve been saving that falls outside the recommended date? Or what about the seed your friend or relative gave you that doesn’t have a date on the packet? Even if outside the “recommended” date, it doesn’t necessarily mean that the seed won’t germinate. But there is one way to know for sure: perform a seed germination test.
The Germination Test:
The concept of a germination test is to take a random sample of seeds from a package and put them in the conditions that make them most likely to germinate. The number of seeds that sprout give you a percentage of the number you can expect to germinate (3 out of 10 will be 30%, 10 out of 10 will be 100%). Based on this information, you can plant the number of seeds that will give you the number of plants you need. If more seeds sprout than are needed, thin seedlings to the number you want.
The most basic test is the very unofficial-sounding “paper towel test”. Soak a piece of paper towel (or a coffee filter) in warm water and wring it out until it’s damp. Count out ten seeds and spread them on half of the paper towel and then fold the other half over the seeds. Roll up the paper towel and place it in a clear plastic bag to keep it from drying out. After a few days, open the paper towel and see if any seeds have germinated. Count the sprouts, record the number (and the date) and remove them from the test; the sprouts can be discarded or planted. Leave the un-sprouted seeds on the paper towel, spray them with water to dampen the paper towel and place the seeds back in the plastic bag. Continue this process until you think all the viable seeds have germinated (if you haven’t seen a new sprout in a while, the test is probably done). The total number of seeds that sprouted will give you an indication of the number of seeds that will sprout when planted in the garden. If no seeds have germinated within a reasonable time (at least 14 days), discard the test and the seed packet.
Most commercial seed is bred to germinate within a specified time frame. An exception is wildflower seeds; they sprout at different times to allow for
weather variations (some may take years).
Some seeds need light in order to germinate (lettuce and some peppers). To test the viability of these seeds, place damp paper towel in the bottom of a clear plastic container, count out ten seeds and space them out on top of the paper towel. Follow the same process of counting those that sprout and removing them from the test until you think all the viable seeds have germinated.
Some seeds germinate very quickly, and some seeds have a naturally low germination rate. For instance lettuce seed generally germinates in 3-5 days and the percentage of seed that germinates is generally 80%, while artichoke seed generally germinates in 14-21 days and the percentage of seed that germinates is generally 60%.
There are other reasons why seeds won’t germinate such as needing a period of moist, cold temperature (stratification); needing to have the outside seed coat weakened (scarification) by soaking in water, manual removal or passing through the digestive tract of a bird/animal; the seed may have an immature embryo; or the seed may need to uptake potassium nitrate found in soil to germinate. Information on these factors is best researched through online forums or reference books.
The good news is that even if you find an old packet of seed, it doesn’t necessarily mean it won’t germinate and grow into a plant. But knowing that you can perform a germination test will give you the confidence to either plant those seeds or toss them away.
And don’t forget to follow the lead of Master Gardeners who find it helpful to keep a garden journal to record what they’ve learned from their gardens every season. Jotting your experiences in a journal will help you learn from your mistakes and celebrate your successes!