Hi Martha,

" Will starting a large tray of seedlings, and plucking them out into
larger pots when they have germinated, work for each of these varieties?
Zinnias have a reputation for not transplanting well, so I wondered if
they need to be planted singly into cells vs scattering a bunch. "

I don't have any experience with cosmos and tithonia, so I will confine my response to zinnias. I think zinnia's reputation for not transplanting well arose from attempts to move established zinnias from one part of the garden or landscape to a different place, by digging them up in a "root ball". Zinnias develop a large root structure and any attempt to dig them up leaves a lot of root structure behind, causing the transplanted zinnia to be severely set back, if not killed outright.

Zinnia seedlings planted in a tray have not had time to develop a large root structure, so it is possible to "prick them out" and place them in individual pots with negligible damage to the seedlings. However, in my case, I find it much easier to place a seed in a small pot than to prick out a zinnia seedling from a tray and place it in a pot. So I don't do the tray thing purely to economize on my time spent.

If I have a large number of questionable zinnia seed, I will pre-germinate them on a moistened folded Bounty paper towel in a Ziploc bag.

I keep the pre-germinating Ziploc bags in a student report folder that has pockets.That way I know where the Ziploc bags are, and they are in the dark when the folder is closed. It is easy to "plant" the sprouted zinnia seeds in small pots.

ZM
(not associated with any brand name product mentioned)

I sow all my seeds into 4" pots and prick out seedlings when they get a bit of size on them. Zinnias are no problem! The "zinnias don't take to transplanting well" is a bunch of baloney for seedlings. Never transplanted them when older, so can't speak to that. Good luck!

Thanks both of you for the input. Do zinnias need dark for germination? I was going to put them under lights on a timer, though I will probably poke the seeds down into the media for moisture's sake, and because of the handy shape.

Martha

Hi Martha,

" Do zinnias need dark for germination? "

No, zinnia seeds do not need dark, or light to germinate. Light has no effect on zinnia germination. So do whatever is convenient for you.

" ...I will probably poke the seeds down into the media for moisture's sake, and because of the handy shape. "

Those arrow-head-shaped seeds do invite poking them into the media point first. And the root emerges from the point, so that may actually be a good idea.

ZM