Zeedman
Garden Master
(added emphasis mine)
A good observation, @digitS' . Because I grow seed crops in a multi-year rotation, I am nearly always using seed several years old. That was seldom an issue, because I used the "hot" germ method (at 80-85 degrees F.) and (usually) had an adequate population emerge. This year, though, I germinated seed at room temperature (about 70 degrees F.)... don't know if that qualifies as "cold" germ, but it is 15 degrees cooler than I have used in the past. Germination was a couple days longer overall, and the difference between seeds of different ages was more pronounced. I track seed germination every year, these were the results:
OK, made a table with seed ages & germination rates, and the entire thing was deleted when I saved the post.
So this is the data, for seed stored in freezer bags, in a metal cabinet, at room temperature:
Bacskia / 2012 / 18 days / 6%
Bea / 2014 / 13 days / 100%
Beaver Dam / 2012 / 18 days / 2%
Elephant's Ear / 2014 / 13 days / 75%
Greygo / 2012 / 15-19 days / 90%
Italian Cheese / 2015 / 13 days / 87%
Korean Dark Green / 2015 / 13 days / 100%
PI 315008 / 2016 / 14 days / 100%
Parker Heirloom / 2015 / 14 days / 100%
Pizza / 2012 / 15-18 days / 65%
Pizza sport / 2018 / 7 days / 100%
Suptol / 2009 / dead / 0%
Taltos / 2013 / 17 days / 16%
Vinedale / 2019 / 7 days / 87%
To summarize, the days to germination ranged from 7 days for new seed, to staggered germination (up to 19 days) for older seed, to completely dead for the oldest. There were a couple statistical anomalies (such as Bea high, and Vinedale a little low) but germination rates were unreliable after 5 years, and total seed death for peppers appears likely after 7-8 years. Interestingly, hot peppers tended to have much better germination than sweet peppers of the same age (4 of the 5 @ 100%).
I could list the results for tomatoes as well, but all germinated in 7-8 days regardless of age, differing only in their percentages. One of the oldest seeds (Elfin / 2014) had the lowest germination rate, at 45%; but most of the 2014-2016 seed was 90-100%. It appears that tomatoes are less sensitive to seed age than peppers. Tomatoes also seemed indifferent to the lower temperatures, maybe only a day or two slower to germinate, with virtually no differences between varieties.
Diamond eggplant (2016) had very consistent germination in 10 days, at 85%.
One observation of "hot" vs. "cold" germination. When I use "hot" temperatures, germination is faster & at a higher percentage... but I get a lot of "helmets", where the seed coat fails to detach. Those clinging seed coats can be detached by moistening them several times, but this demands more observation & effort on my part. When germinated at room temperature, there were very few "helmets", maybe 5%.... but those transplants need to be started earlier. For peppers (and possibly eggplant) that may be an extra 7-10 days early.
For peppers, the major difference in days to germination for "cold" temperatures caught me by surprise. I'm leaving the lights on for 24 hours for at least the next couple weeks, in hope of making up some time. That strategy was successful one year, when I was about a week late planting.
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