Depending on what your coop looks like you might be able to just put the heat plate out there. But there can be other issues, the brooder may be a good idea.
Since people often like photos I'll show my 3' x 6' brooder permanently built into the coop. That red shows where the heat lamp is. In winter I wrap the whole thing but this set-up is for spring. It doesn't get that cold but can still get nippy.
Since people often like photos I'll show my 3' x 6' brooder permanently built into the coop. That red shows where the heat lamp is. In winter I wrap the whole thing but this set-up is for spring. It doesn't get that cold but can still get nippy.