Leave then be. IF they want to roost they will jump up there. Some chickens just prefer to be on the ground. About half my flock hangs out on the ground the other half roosts and there is more than enough space for them all on the roosts.
And you said a pole, is that a metal pole? A roost needs to be wood, and flat. Wood, so that it won't be so cold, and flat, so that when the temps do drop, they can keep their feet flat, and sit on their feet, keep the feet warm, too! We used a 2x4 rafter that they roosted in. That is, the ones that roosted. The others would just get on a milk crate off the ground. They just wouldn't roost. Some will, and some won't.
I just got back from the coop and my 2 yr olds are on the roost. All of my 18 week olds are on the floor.
I used to leave the light on until 9 pm but I read " living with chickens" and I learned that by shutting the light off suddenly that they cannot find there roost.
I lost a pullet Saturday night due to a raccoon or opossum so that's is the reasoning behind my building of roost poles.
I used round wooden fence post approx. 2 1/2" in diameter. I can square off top if necessary.
I also use 2x4's. I have the 4" side on the top. I think it's really important in places where it gets really cold. They need room to cover their feet with their feathers to keep them warm and free of frostbite.