Integrating different age chickens

[sesa]

I've got 4 chicks that are 3 weeks old, and 1 year old hen, how should I go about putting them together?

 

[azygous]

That should be easy. But you need to do it gradually. Put up a partition so they can all see each other, but the hen can't peck the chicks. After about two or three weeks, open a small pop hole in the partition so the chicks can go visit the big hen, but the big hen can't fit through. This way if she decides to bully them, they can race back to safety on the other side. Eventually they'll learn to outrun her, and learn the pecking order. By the time they no longer can fit through their little pop hole, they should all be getting on well. Then you can take down the partition and relax.

I made a partition in the run as well as the coop.

I've used this method, that I like to call the "panic room", and it's worked very well for merging two different batches of chicks. however, with the second batch, one of the older hens decided to appoint herself the bully and she was keeping the chicks from going in to roost at night when it was time for them to roost together. I had to construct a "jail" for her to be in every night until the chicks learned to roost and not be scared she was waiting to ambush them.

With one older hen, I don't see that you would run into any problems. She should be very happy to be the alpha hen to her very own flock and not be lonely anymore.