I think they would be fine, of course with proper supervision especially if there is no mother hen to keep them in line. This spring I purchased more chicks and put them under 5 different broody hens. Within days, they had the chicks exploring outside and it was much cooler than 85 degrees. Every so often the hens would find a safe spot and cover the chicks then after a bit of time, they would all be off exploring again. Momma knows best. They won't need grit if they are outside pecking at the dirt, they'll find plenty on their own. My hens have been keeping their "flocks" away from the others so this past week I have been feeding them outside the coop so all the chicks or I should say pullets (they're 5 and 6 weeks old now) can get used to each other and start their pecking order rituals. After all, come winter, they will all be sharing roosts in the coops.
