I would like to ask a follow up question. I have a broody hen (she’s been broody for about 3 weeks) I just bought chicks to try to put underneath her but realize I didn’t think it through all the way. I will wait until night time to put the chicks under her but then what? Do I leave momma and babies in the coop with the rest of the flock? Do I have to separate them? If everyone is all together, what do I feed them that will be nourishing to chicks and layers? I’m kicking myself now for not being more prepared
You can leave momma and babies with the rest of the flock, or you can separate them. The hen will typically protect her babies and make everyone else stay far away. Some hens do this better than others, and the size of their coop & run can be important too (In a small coop there is not enough space for the other chickens to stay away from the hen & chicks.) So leaving the hen with the flock works well for some people, but causes problems for some other people, who have different coops or different hens.
For feeding a mixed flock, just give them all chick starter or flock raiser, and provide a separate dish of oyster shell. The chicks need high protein and small pieces of food, but those are fine to older chickens as well. The laying hens need more calcium than the babies, and chickens are usually pretty good at self-regulating oyster shell according to their own needs: more for the layers, much less or none for non-layers such as males, growing chicks, and broody hens.
If you leave the entire flock together, make sure the young chicks can reach the food and water. Some styles of waterer and feeder are fine for chickens of all sizes, but some are only suitable for adult chickens (like treadle feeders where a chicken must weigh a certain amount to make the lid open.) It is also good to have at least two feeders, and at least two waterers, to reduce competition and conflicts.