When to put chicks together

[crawfordcoop]

I have 2 sets of chicks. Older chicks that r 9 to 10 weeks old and chicks that r about 3 weeks old. The older chicks are in our outside coop and the younger ones r in a brooding box in the house. When can I put the two groups together? I have a heat lamp in the coop and the younger chicks r getting their feathers.

 

[curious chickee]

I have the same age gap. My 8 week olds are in the main coop and run. The three week olds are in the small coop inside the run so they can see each other. I don't plan on fully integrating them until the younger ones are similar sized to the older.