By Lou Bull
(companion notes from our session demonstrating these methods in June 2016)
Why test seeds?
- Helps determine quality of seed
- Helps determine quantities of seed to sow to get the numbers of plants you desire
- Advisable for seed older than two years
- Seed lots with low viability may have other less desirable traits if grown for future plant growing
What is viable seed with good germinability*?
- Viable seeds have a healthy embryo under the seed coat waiting to be “woken up” and ready to grow
- Seed with good germinability are easily woken up and prepared for germinating easily under its preferred germination conditions
- *You may think we made that word up, but it’s the proper term!
Methods for testing
Consider these before starting:
- Inspect the seed lot and compare collection date with potential expiry date (the Seed Savers Handbook has a list at the back of it)
- Keep actively growing seed to ensure it remains viable
- Good storage and cleaning in the first place really helps ie: store in vermin proof box in a dark space and, as much as possible, where there are only small temperature fluctuations
- Squeeze test – squeeze the seed to see if it appears full and firm
- Cut test – cut open seed and look for a lovely filled seed with a white embryo that doesn’t appear shrivelled or damaged
- Use paper towel (or fabric) and a soft plastic bag
- Select seed to test (select a number that can be sacrificed which will depend on how much seed there is) and work with numbers that can be easily converted to a percentage
- Place seed onto paper towel and moisten slightly
- Roll up the towel and place into a plastic bag – keep this open to air
- Place in a location that has the temperature similar to what is required to start germination (try the top of the fridge or a living area for constant warmth in cooler weather)
- Inspect after a week to count what has germinated then complete the test after about two weeks
- If the test failed (no germination), check if you have closely replicated preferred conditions
- Record your results (e.g. if 8 out of 10 seeds germinated = 80% viability)
- As above however you can do this in real conditions in the soil or potting medium
- Amount of seed to test would ideally be a minimum of 25 seeds but will depend on seeds available
- Seeds should be selected randomly
- Keep good records
- Testing becomes important if seed is older than two years; is to be shared; and/or if you are not sure of viability
Germination test progress pictures
We’ve also added this information as a PDF fact sheet in our resources section.