Just saw that you're in Vermont. Year round grass is almost out of the question in that climate, especially if you're having to clear to establish pasture. Horse quality round bales are also much less commonly produced and fed in New England. Maybe you'll find a source near you, but where I grew up in MA (very near the VT border) almost all round bales made by local farmers were cow hay. There's a difference and trying to get by with poor quality hay means a malnourished horse at best and a dead horse at worst. Horses can't eat what cows can.
To back up what K Putnam is saying - right now in my backyard I have three horses that have come to me from novice or hands-off owners. I've taken these horses on to help out their owners who were otherwise out of options. One was crippled and in extreme pain from having been kept out in the pasture with the owner's cows. This was not especially rich grass, but it was still too much for this pony - he became extremely obese and his feet were overgrown. When I saw him on the farm, I cut off 4" of excess hoof and still had more to go, but was reluctant to proceed without veterinary intervention. This type of laminitis can be deadly. The owner was not able to commit to keeping the pony in a dry lot on a diet or able to afford x-rays of the feet. So, the pony came home with me. 6 months later he's ditched the excess weight, but his feet will take at least a year to rehab and will never be normal. In speaking with the old owner, I am going to try to rehome him, but have learned that the pony won't tolerate a grazing muzzle and won't stay in electric fencing, and has also dumped all the kids in previous re-homing attempts. So it's going to be a long road for me to get rid of this thing! The owner didn't have the knowledge to realize how dangerous this pony's "limp" was, and how close it was to being an irreparable condition.
The next two came to me by way of inexperienced owners causing training problems. One is a young and gorgeous horse purchased because the owner "always wanted a horse and he had a beautiful spirit." They were not prepared for the costs of horse ownership, and it's an absolute miracle she was not injured by this increasingly headstrong, large young horse that never had boundaries set or rules about personal space enforced. I took a chance on him and because of the lack of proper handling, he had developed an attitude problem. Luckily I have not gotten hurt being dumped multiple times (ha!) but even with 20+ years of riding and training under my belt, I had to send him off to another professional for boot camp. He's finally coming around to be a solid citizen. The third horse is a combination of bad training and medical problems - an inexperienced owner started following a popular "natural horsemanship" trainer who is known for their dvd's and bad ideas. The way the theories were implemented by someone who couldn't read horse body language created a horse that now bolts backwards in a panic at the drop of a hat in response to any situation. SO incredibly dangerous to humans and the horse. The horse is now blind in one eye from being tied by someone who said "Oh, she's been doing so much better!" and after the horse panicked and bolted backwards, the snap shot straight into her eye and detached the retina.
Like I said, not trying to be discouraging, but a mentor or lessons or training is incredibly important because horses can kill themselves in creative ways and because of their size and flight instincts, can take you with them pretty easily. I've seen a lot of injuries and dead horses from the "it'll be fine" attitude, which is why I come across a little strong on this topic. I love educating people about horses and always invite anyone to come out and see them and learn a bit about handling and care. Horses are great! You just have to know what you're getting into.