Testing seed viability

test viability

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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

 

Germination test

  • 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)
Germination test images

Setting up a seed germination test

Using soil

  • As above however you can do this in real conditions in the soil or potting medium

Important considerations

  • 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.

Seed viability document image

Click to view as a PDF (336kb)

 

 

 

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