It’s 11 weeks to the last frost in my neighborhood, and I’ve been gripped by seed-starting fever. My family will not thank me if I take up any more room in the refrigerator for my seeds than I already am, so before I can place orders with my favorite seed catalogues, I need to test the seeds’ viability.
Seed viability is another term for the likelihood of a packet of seed to germinate. Viability varies among genera. Many root crops’ seeds, such as onions or carrots, remain viable for one year, while some melons may be viable for longer than 4 years. If kept in proper conditions (low light, low temperature, and low humidity), seed may remain viable for many years past their average.
A simple way to test seed viability
To test whether your leftover seeds are viable, gather together the following supplies:
Germination and potting up
Remove the paper towel from its bag and gently unfold it.
The photo above shows an excellent germination rate, and indicates the seed is still quite viable. But they’re not going to get much further growing on a paper towel, so it’s time to pot them up.
The seedlings at this stage have only their cotyledons, or seed leaves. As fragile as these seed leaves look, they’re more resilient than the stem, which will be easily crushed by handling. Grasp the leaves and gently but firmly pull them up from the paper towel. Some of the roots here have grown through the towel, so we’ll tackle the easy ones first.
If any of the seedlings have grown through the substrate (paper towel), there’s no need to wrestle them. Using a pair of scissors, trim small seed mats and handle the seedlings by them. The mats can be planted along with the seedlings, and will eventually compost.
Check the seedlings daily and do not let them dry out. Watering from the bottom will help to prevent damping-off disease. When the seedlings have developed one or two sets of true leaves, they may be potted up again.
Good luck with the growing season ahead!