>> You keep them so carefully I bet they will retain viability for quite a while, Rick.
Thank you very much! If fussing and fiddling are good for seeds, these should last for 100 years. If I had kept up with new-silica-gel-pkts, they might be in really great shape.
>> There are a lot of packets! and some are from 1999, the rest from 2006.
Well, if it was harvested in 2006, that's only 8 years. I see "4-6 years" listed as sunflower seed viability under ideal storage conditions.
If they were very dry before going into plastic, at least they were protected from swings in humidity, and probably did have ideal conditions for at least the first several years.
I expect commercial seeds to be dried very thoroughly, but I've also learned to look at commercial pkts to see if they say "packaged FOR 2006". That only means that they met national standards for commercial seed viability in 2006 - they might already have been 2, 3 or 4 years old.
I bet you would get 10-50% viable seeds. The number of authorities solemnly announcing how long seeds last is greatly exceeded by the number of people who left an open paper bag in a shed for much longer than that, sowed thickly, and got a good stand of whatever it was.
Because I like to fiddle, I would be tempted to put more effort into old second-hand seeds than new, carefully selected ones (I'm not sayin' that makes any sense whatsoever ...)
You COULD give them an overnight soak in 0.1% hydrogen peroxide (1.5 tsp of drugstore peroxide per cup of water). Then test their germination rate on paper towels in a Ziploc baggie (sunflowers at 70F). And label everything like a science experiment. Maybe plant out each sprout into a 4" pot.
If the seeds have lost vigor and used up most of their stored food through long storage, I would expect lots more of them to sprout than have enough strength to fight off mold and push through an inch of soil to find the Sun. If you coax them with dilute peroxide and sterile potting soil, their apparent "viability" will be much greater.
Or just mix all the sunflower seeds together and sow them 4 times thicker than you would otherwise. Maybe 100 times less effort for slightly less return.
I swear: the BEST way to increase the germination rate of seeds is to assume they are all too old, then sow them too thickly. Those little rascals ALL seem to sprout if I do that!
