Another quick question regarding seeds that require dark to germinate. I have started several seeds in vermiculite and am beginning to see some germination of maybe 3 or 4 seedlings. There are probably at least 50 seeds in each container of vermiculite. At what point do I bring this out of the dark and into the light ? Will these early risers survive in the dark until the others catch up ?

Thank you,

David

Just for my interest, what sort of seeds require dark to germinate David?

Hello Ken,

Statice, Cosmos, and Zinnia Benarys Giant are the ones that I have. I ordered these from Harris Seed and the packets state they need dark to germinate. I've been very successful with my seeds this year but these are the first ones I came across that specify to start in the dark.

David, your early risers will get tall and spindly very quickly if you leave them in the dark. Can you possibly lift them out and pot them up to bring them out to the light? It shouldn't take more than a day or two for the others to pop up, but in the meantime the first ones will get very weak if they're in the dark.

I've always thought that 'seeds need dark to germinate' thing can't be right, because then how do any of those seeds germinate out in nature, where they simply fall on the ground? I've certainly had Cosmos and Zinnia self-sow in the garden without any dark protection other than maybe some soil or leaf coverage.

If you have more than one tray planted, you could simply bring a whole tray out to the light and see what happens. I'd imagine most of the seeds have germinated and are getting ready to push up above the vermiculite.

Elaine, thanks for the advice. I was wondering the same thing about seeds in nature !!

I will probably lift them out as you suggest and see what happens. At this point I would rather sacrifice 3 or 4 than the other 47 so I plan to keep the rest in the dark. I also agree about the other one's probably being ready to germinate. I have sown several 72 flats of seeds over the winter and they all seem to come up within a few hours of each other.

Maybe vermiculite wasn't the best medium for seeds needing dark........a deeper planting in peat would probably keep them in the dark while they wait on their buddies.

True, but vermiculite sure makes it easier to thin/separate your seedlings and pot them up or plant them out.

I think of these as randomly covered and uncovered dependents in nature; they're on the ground and ready to go, but they need just the right amount of matter to fall over them for the required time of darkness, and then might need another random act to reach the light. Leaf cover that moves in by wind and away by bird, seeded ground that is disturbed at an opportune time by squirrels or other foragers, rain to wash away the layer of covering, etc.

I sow mine very sparingly now, and as soon as the first one sprouts I provide light. If I don't get enough from that batch, I'll set it aside for potting up and start another. Vermiculite sowing makes this so very easy to do.

Most people confuse germination with when you see the seed sprouting above the surface.

Germination is the waking of the seed, and confirmed by the emergence of the root from the seed. You will never see this, unless you are able to observe the actual seed. Don't confuse this with the swelling of a seed, which is the prerequisite absorption of water. Germination occurs most often one to seven days before sprouting above the soil. With certain species, germination will happen many months to a year before sprouting.

While some seeds need dark to germinate, no seeds need dark to continue to grow after germination. Thus, when your first seeds that require darkness emerge from the soil, many more have already germinated below, and will continue to emerge above the soil surface.

It sure sounds like you know what you are talking about, Rick. I never even thought to segregate the two, germination and sprouting. But I also have never started the germination process in total dark either. All my vegetable seeds are beneath the surface of the germination media so I am not quite certain what further "darkness" would be necessary. Needless to say, I am not the sharpest tack.

http://www.britannica.com/EBch...


The Encyclopedia Britannica hints that there are many kinds of dormancy and combinations of conditions that break it or enforce it.

Inhibition by light is found in chive, garlic, and several other species of the lily family, jimsonweed, fennel flower (Nigella), Phacelia, Nemophila, and pigweed (Amaranthus).

My guess is that the evolutionary "purpose" of dormancy is to keep most seeds from sprouting unless the conditions are likely to be favorable to the seedling. That, and also to keep SOME seeds dormant for next year no matter HOW favorable conditions seem right now.

One thing that surprises me is how seeds manage to stay intact, viable and undigested during multiple years underground, moist and surrounded by microbes hungry for organic food. Those seed coats do very well to defy mold, fungi, worms, insects and bacteria!

It certainly mocks my attempts to maximize seed viability by worrying about the difference between 50% RH and 15% RH inside cool, dark Ziplocs!!

It's really a small percentage of seeds that require darkness to germinate. Vegetables even less. For most seeds, light as illumination is inconsequential.

Yes, seeds are one of my things. I created a seed germination data base with over 5300 species, based on Dr. Deno's now public books, but have added around 700 additions taken from dependable individual experiences. I've taken 100s of photographs of seed, as well as germination and seedling growth.
These are Astragalus seeds at or past germination:

Thank you guys and gals for the information. Upon closer inspection I can see many other seeds that have begun to swell and crack so I have given them the light and will wait and see.......