Most will not germinate inside of their coats of fruit. Wouldn't want to start growing while still hanging from mama's branch.
Most will not germinate without passing through the killing time: winter. This is more true for seeds that mature late in the year than those that mature in the spring.
Some will not germinate without light or a certain level of heat. This strikes me as "seed common sense."
Which poses the question:
Why on earth do so many of my seeds insist in germinating in complete darkness and genuine cold -- in my refrigerator, early February?
The worst offender this year was Monarda fistulosa - Wild Bergamot. Now I've got two 72-cell trays of it and a chia-pet like leftovers container full of stragglers. They began germinating in mid-January.
Flowering Dogwood continues its abysmal record (third year in a row) of early germination. Of all the natives, the adorable baby dogwoods seem most sensitive to damping off and other seedling blights. Might behoove them to wait for sunnier, warmer days, no? Since I collected and cleaned about 300 drupes, I'm going to have to find some serious space before doing anything about them.
Mayapple seems to be an early riser too. I took about 70 seeds out of the refrigerator today, 3/4 of which had swollen and parted their seedcoats, sending an exploratory rootlet out into the moistened peat moss in the film canister which was intended to be their home until at least mid-March.
Maybe they germinate early in the wild too, underneath a protective layer of snow and rich organic duff?
Other seeds caught germinating in today's refrigerator census included blue houndstongue, eastern hemlock, and the cache of seeds a mouse left in a pile of old lumber in the Catskills that I was so curious to identify...
Curiousity is great in the waning heat of August, potentially deadly a week before valentine's day.
All of this refrigerator germination makes me wonder: how is it that certain seeds are reputed to lie dormant in the "seedbank" for years, even decades? If a cold dark plastic vial inside of a cold dark mechanical vault won't stop the "tasty Chokecherries - Alder Lake 9/5/08" from germinating, does burial under a fallen log, or several inches down in the soil, have a different effect? Are those seeds which lie dormant in the seedbank the same ones which "never germinate" in a seedling tray - ones which carry some sort of mutation or even defect which insures extra-long dormancy?
Some native plants (viburnums, for example) routinely take two years or more to germinate. Perhaps other plant species selectively manifest this "patient" quality.
Viburnums may seem patient relative to some other seeds, but - that didn't stop four maple-leaf viburnum seeds I collected two years ago from germinating sometime in the last month or so...
...in the refrigerator!