Hello and welcome
I usually paddock a portion off and save it up for winter foggage. I restrict ours and they spend time in the arena with hay nets for a part of the day. One of mine is a very good doer so I have to be careful, though our pasture is poor - which is rather handy for us!
Lots of people use grazing muzzles - I'm sure MP on here et al will fill you in.
Ours are out all the time anyway so the grass coming through slowly gets them back slowly onto the richer grazing, then once they are looking a bit more sleek, we fence off the grass and allow them a small amount
I have bought a brand new grazing muzzle for my horse (as he had worn the hole in the last one down so much it wasn't really a hole anymore). He is have it on as soon as they move into the rested paddock which will be around March 1st. I hate the spring grass - for a few weeks my lovely, saintly, quiet boy turns into a spooky monster!
our lammi prone boys are currently stabled overnight and in nothing paddocks on hay , their summer field is resting and is growing the green stuff - in about a month, the girls who are out 24/7 will move over onto a section and mow it ready for the boys to follow on somewhere around April - they will get the grazed grass sectioned off with hay for a week or so - slowly reducing the hay to introduce the grass growth, and then remain on restricted turnout for the summer, opening up fresh areas and rotating as we can - its a nightmare but the only thing that we have found works for us, Tess goes first and everyone else round robins behind her.
We have kept half of my field (nearly 2 acres) foggage all winter while the herd has been in the sacrifice paddock on hay. Come March is we'll let them eat the foggage, then set up a track all around my paddock for the summer. It's hard to keep them slim.
They live out so they start to get used to it coming through on their winter side. Then when the summer side has some decent growth on it the first week I move them on to it for the afternoons only and then let them on it all the time from th we week after. The only reason I do that is because my coloured colics if given the chance to gorge.
Mine lives out all year so it creeps up on us. Usually around the start of March (OMG, that's in a couple of weeks!) I will keep an eye out and if its mild, I'll set up a pen (about 3-4 stable sized - i have a big horse) for my very very good doer in the field and he goes in there overnight. It soon becomes a bare patch and it is basically his makeshift outside stable overnight for the summer months.