We have two sets of chicks that are 6 weeks apart (the first set is 7 weeks and the new ones are a week old). When would be a good time to start integrating them? Not sure if it matters, but the older ones are ISA Brown, and the new ones are Barred Rock.
The older ones are close to going outside, I would move them out. When the younger ones are ready at about eight weeks I would divide the coop and house them side by side for a week or two before doing some supervised mingling. Keep at it until you feel comfortable leaving them together.
What I suggest for two groups of chicks several weeks apart in age is to set up the new chicks in a safe pen in the coop and brood them right alongside the older chicks. That way the two groups become used to being part of the same flock as the younger chicks grow up, making integrating a snap later. By brooding the younger ones alongside the older chicks, it's possible to integrate them much earlier since they all know one another from the time the smaller ones were tiny and non-threatening. You might approach the integration much as you would if the older chicks were adults, by using a panic room. This is any kind of safe haven with entrances where the larger chicks won't fit. It's possible to begin integration as early as three weeks with this method. I wrote about it in my article about brooding outdoors, linked below this post under "Articles".
