how long can i make fondant roses in advance? i need to make many. also, do i store them in a plastic container or leave open in the air? thanks for your help. =)

air tight container and dark so color doesn't fade.

I store them in a covered box but not air tight, at least not unless they're dried rock hard already. Most of the time I put a layer of paper towels in a cardboard tray, lay the dried flowers in the tray and tape waxed paper over the top.

Make sure to let them dry in an open space fisrt so the humidity don't kill them. And then store them in a box in a dry place.

how long will they keep?

They can keep for a long time as long as they are stored fully dry. If they have some moisture they can become brittle.
Edna