Did you buy the wrong seed packet, have an abundance of that plant in your garden, or were you looking at that particular marigold for its pest-warding properties?
My hubbie and I planted them in the enclosure today but then I noticed the container said "African marigold". I put them in there initially because they were pretty and I remembered reading they were edible. My tort has not tried to eat them and actually did not seem interested in them at all. I guess I need to dig them all up now huh? Ugh..
Initially, I didn't realize the difference between the two marigolds, either. I would probably err on the side of caution and dig 'em up. I know torts *should* be smart enough to know what's good and what isn't, but ya never know when they decide to not be smart. Feel free to plant them outside of the enclosure, though.. people use french marigold to repel pests naturally.