If it says august plant them i thought they might be tender why not? in a lot of gardens these will seed themselves and come up when they feel like it

I think the autumn sowing would usually be done where they are to flower. When they have self seeded for me they have not normally apeared until the spring. I think now you've got this far I'd leave them in the greenhouse but they do need potting on. I would also cut down the watering as they look rather lush and need to harden off a bit. However as you have a lot why not put half a dozen outside on the off chance and see what happens?

Yes I do have quiet a lot so no harm in trying out a few. Many thanks for your advise.