Horse Answers

I wouldn't bother with bushes as they'll only get eaten. Any tree that you plant will need a good sturdy fence round it to protect it from the horses trying to eat it and scratch themselves on it. There are lots of poisonous trees like yew trees, and acorns are poisonous to horses, so don't plant an oak. I would look into it a bit more as so many trees have berries or nuts that horses mustn't eat. If you really want shelter, a field shelter might be a better bet.