3.5 acres for one big horse and one little pony? I know it depends on soil type quite a bit. I would want them out as much as possible all year round and obviously would be able to feed them hayledge in winter.
sounds plenty, was always taught it one acre per horse plus another half. Nice if theres enough space for them to get up a bit of a gallop if they feel the need imo too.
plenty i use to have 4 1/2 acres with 1 big horse and 2 ponies and always had shed loads of grass. they were out 24/7 and didn't really need feeding in winter. but i did look after in really well.
I have one horse on 2 1/2 acres and find I have too much during the summer when he is on restricted...so leave it to grow for the farmer to take hay from. And in the winter I have no probs with poaching or lack of grass and he is out 24/7 from Oct to April.