Keeping commercial seed packets for an extended period of time can be done for many reasons. Maybe you bought them and it wasn’t planting season, maybe you were waiting for some space to open up, or maybe you just remembered they exist!
Will 20 year old seeds grow? Yes! However, not every seed will be as viable as fresh seeds once were. There are many factors for seed storage, and you may only have a few leftover seeds with the potential to germinate and sprout into full seeds.
Long forgotten, rare seeds that have never been planted can still thrive. Yet the percentage of seeds that will take and germinate can vary greatly. Even sealed seeds, well cared for and stored, may not be as viable as fresh packets of seeds you could buy in the store.
So how do you tell? How do you store seeds if you want them to remain viable? Seed vitality is important, as seeds are living things. A viable seed may only need some care and the passage of time to sprout anew, but viability over time does tend to diminish.
How to Store Seeds Correctly
Different techniques for seed storage are available, but the most important are cool and dry conditions. Seeds kept in warm and damp conditions may germinate and die before being planted, or even begin to show signs of fungal infection and mold.
Don’t waste a quality seed with improper storage, make sure you follow the storage guidelines on the back of the packet that most seed companies will give you. Seed manufacturers have to store these when they are transported to stores, so they know what they’re talking about!
Premature germination can be an issue, as when a seed germinates and sprouts it will need different conditions. Moisture, temperature, oxygen, and light are all vital to a healthy seedling growth. Unless planted in soil, the seedling will die and kill the seed with it.
Testing Seed Viability
A simple seed viability test can be done to see how many of your seeds may germinate. This test can be done on any types of plant seed. Flower seeds, fruit seed (like tomato seeds), and vegetable seeds (like green onions seeds).
Simple get a damp paper towel and lay some – but not all – of your seeds onto it. If your seeds prefer the dark, then consider laying a second damp towel on top of them afterwards. You can even consider then putting these in the fridge to keep things cool if needed.
Obvious tomato seeds, bean seeds, and flowers seeds all have different germination requirements. So make sure to check so external factors don’t ruin your viability test. A high temperature greenhouse or a cool temperature fridge can both germinate plants.
This test will show you which seeds sprout, and which don’t. While not a perfect test, it will give you a rough idea of what percentage of seeds are still able to sprout into seedlings, and which are dead or dormant after such a long time.
How Long do Most Seeds Last?
Seed catalogs will have varying ‘expiration’ dates for their seeds, but really seeds never go out of date. Instead, these dates are more of a suggestion, a best before if you will. So long as you check the seed surface and seed coats for signs of mold or fungi, you should be safe to plant those seeds in seed trays.
It’s not reccomended to keep seeds for more than a few years, as this will dramatically decrease the lifespan of your plants, and the vitality of your seeds. After about three years, you may struggle to get a quality yield out of your seeds when you plant them.