Since I haven't been able to sow seeds for a few years, I have a glut of older seeds (of many types) and have been reading up on older seed germination. Here's a synopsis of what I've read:
With really old seeds you want to introduce water very slowly for two reasons. One, they can get so dry that they'll imbibe water so quickly and forcefully that they can leach solutes and may even burst their cell walls, leading to the death of the seed. Two, aging creates DNA damage. When seeds begin to imbibe water they start making repairs to their DNA. Old seeds have more damage so need more time to make repairs. If conditions are right and they are suddenly fully imbibed, they'll try to germinate before those repairs are fully made. These seedlings will often stall out at the cotyledon stage and eventually die.
Old seeds also tend much more sensitive to hypoxic conditions during germination so using a 1:19 ratio of 3% Hydrogen Peroxide to Water can help. I've used Hydrogen Peroxide this way for seed germination for at least 15 years and found it helpful. It's nice to see scientific studies now that confirm it.
Other possible additives to boost old seed germination include sugar, nitrates, Gibberellic acid, seaweed, & more.
I plan on experimenting with different methods & additives. Perhaps try some priming...
Since old seeds need clean conditions, very gradual imbibition, and earlier exposure to light, I'll probably do the baggie/Deno method (using coffee filters since they hold less water & roots don't get entangled in them as much).
I also have some coarse vermiculite to try Jonna's method on the old seed. Her site no longer exists but here is the archived page:
http://web.archive.org/web/201...
Fingers-crossed for everyone's geriatric seed!
