Hi
The area must be closed with high walls. At flag is Up farm walls are 8 feet high in Monty's round pens. Myself I work with a roundpend with a fence which is approx 5 feet high. It does not need to be a wall with solid planks. If your manege is not fully closed or the walls are not high enough, you can use ropes or lines to close the entrance, or tied at the pillars to "elevate" the walls.
You can achieve join up in a square or a rectangle area, but if you can manage to have panels you put at the corners, making an hexagon, it's better. This way the horse will not be stuck in a corner.
Usually, a round pen has a diameter of 50 feet, more or less.
If your manege is bigger, prepare to run! Our you can also try to restrict the area with panels, old tires, etc You don't need a super solid structure, the horse will not run into it, but you need something stable enough so it will not fall on the horse.
Hope it helps.
Have fun & keep safe

Also : it's better if she can't see her friends during the join up. She will not be distracted and it will be easier for her to get her attention.
Also, you can let her in the manege half an hour so she can settle down if she is stressed after leaving her friends.
If the walls are not high enough, yes, she may jump, but unless you have a road or other dangerous thing, it will not be catastrophic anyway.

Thanks so much, think I'll try to curve off the corners as you suggest and try to raise the fence line. Great idea about letting her in early to settle down! Going to try it this evening, big lesson for me as well as her!

Tried join up this evening; we managed to get all four signs and her turning in but no follow-up. I've gone back and looked at the videos again and don't think I had the right body language and I also forgot to try arcing in front of her. I don't want to over do it with her so how long should I wait before I try it again?

First, congratulations for getting the four signs on your first attempt.
I understand you had not the follow up, but probably not a good join up too.
first, choose the place to make the join up. near the gate and near a place where the mare can be distracted, that's no good.
The most common mistake is to look at the mare (because you want her so much to do the join up / follow up!). Don't look at her, and at least not in the eyes but keep her in your peripheral vision. look down
Your fingers must be closed. The line properly coiled and don't move it, arm low. Bring the other arm across midline of body.
Don't advance toward the horse, and even move slightly away, then stand with your shoulders at a 45 degrees angle. stand means wait, and look down. your shoulders must be rounded. Your energy is down, low pulse rate.
if it does not not work, you can try arcing, and then stand again. and again. each time, let the horse the time to decide to join you.
If it still doesn't work, you can try to touch her slightly and the move away a little bit and stand.
If you think your tried to invite to early you can send her away again and reinvite later, but don't do that to much.
When join up is done, give her a good rub and tell her how a good girl she is and walk away. walk away confidently, don't wait for the horse. act as a leader. and don't look back to check if she's following or not. when you walk, change directions and she will follow you.
In your body langage, the most important are your eyes. If you need to concentrate on one thing, concentrate on your eyes. be calm and confident.
I think you can retry tomorrow.
You are doing good, you just need to practice. If you can you can practise with other horses. It's like learning a foreign langage. the better way for learning is practising.
If you have a friend who can take a video, you'll be able to analyze what you are doing. You'll also be able to share the video on youtube if you want help from the other students here.
Keep on the good work
- Cyril

Well done it does feel like an amazing experience i have made the mistake of allowing others to have ago at traing and i have to say it has now resulted in some negative behaviours from my horse oscar i have returned back to basics and tryed join up today to say it was a struggle is an understatement the other trainers used whips thats why they no longer train with me but because im using less violent means oscar is pushing the boundries i can push him one way useing montys method but not with even 80 0/0 sucsess and geting him to turn onto the other way he stands and stares at me and i have to become very animated swing the rope and flick it at him feel like i have lost a battle i should be winning in the end i just let him join up with me then stroked and we did a few backing up lessons that he is not so stubborn with !! oh well slowly but surely we will come back together wish me luck !!

hi he's standing and staring at you as he's not understood what you expected him to do, I have this sometimes when asking our 2 yr old r to do something different.
when getting him to change direction, did you cross over to step infront of him showing you want him to go the other way, then when he turns you go into the position to make him go on again and eye contact when you tried to tuen him, did you loose eye contact?
I'm still a novice at that this, so someone correct me if I've got it wrong :D
Always learning!
Mel
x

Hi unicorn - I am pleased to note here that you have tried join-up even if it was not all that successful at least you had a go. You do have to be fairly strong when you wish them to turn away from you and you do need to really flick the rope - maybe be hit it against you to get a noise effect too - and really square up on him with your eyes on him. Good luck with it I am sure you will get him back once you have done a couple of successful join ups.