[MissMoustache]

I'm no expert.

But from what I've seen you can grow marigolds in the small cells until plant out. After all they're sold like that at the box stores and greenhouses. However I've read that they do better with something a bit bigger because they get root bound otherwise. In short I would pot up.

I have grown marigolds the last few years. I usually space lights 2-3 inches away. I'm paranoid about scalding or setting fire to the plants. It ain't going to happen...but it keeps my anxiety happy with a little more room. Long story short on that...yes. One inch to about three is good for French marigolds.

I've never tried taking marigolds out before Memorial Day weekend here. I don't know how cold hardy they are but I think experimentalism is the stuff that makes life fun. Go for it! At a low of 60 they should be fine.