Can I put 8 week old chicks in coop with 3 month olds ?

I don't know what everyone else will say but I don't think you should. When I put my younger BR with my few weeks older RI/LH they were picked on mercifully so I separated them again. But that's only my advice!

 

When I add new chickens to the flock I section off part of the coop with chicken wire. That way they can see and get use to one another. I also have two runs that are divided by wire, one is 12x20 and the other is 20x20. Each run has its own pop door, they can see each other when they are in the coop or in the run. After about a month I take down the divider in the coop and the all use the same run. I have never had any problems, the old girls still need to let the new ones know who is boss.

 

I agree with Captainmoose, that's what I do as well. By the time I take the divider down the older chickens are already use to the littles and no one gets picked on.

 

I put 3 month old chicks in with my Rooster and 3 hens and they got along fine, but I think Silkies are just naturally sweeter than other breeds.

I wouldn't do that with my Australorps.

 

agree with keeping them separated with some visibility when confined. it also helps if you can let them out to free range with lots of space together before you confine them together.