Have you stopped feeding?
When (Date) do you usually stop?
When (Date) do you begin spring feeding?
I usually stop feeding when it looks as though the bees have enough for the winter. I winter some in single med. depth supers, single deeps, double deeps and variations of the above. I usually can tell by the weight of the hive. I've been experimenting for the past two years, and have been feeding during the winter (mostly patty form). The last thing you want to do is to stimulate brood rearing in the middle of January (in Michigan, that is!)
I begin Spring feeding as soon as they begin flying on a daily basis. Some of my hives this year were honeybound and I had to remove quite a few frames of honey to allow for brood nest expansion.
My advise: Evaluate each colony individually and feed accordingly. Don't forget to reduce the entrance on weak hives to prevent robbing.
I don't feed in the fall except in special circumstances. This year I shook them down to regress to 4.9mm so I'm feeding honey. Most years I don't feed. If I robbed their honey and then the hive felt lighter as winter approached I might feed.
In the spring, it's a crap shoot. Unless you think they are starving I just feed to stimulate brood for the honey flow. Here there is a very early flow of wild plums and my very large pear tree. I try to see when I think they will bloom and start feeding about three weeks before I think that will happen. Probably I'd just start when it seems late enough that spring is here and the bees are starting to fly. If they aren't they won't take it up anyway. In the spring I feed syrup a bit more watered down. I feed honey for winter feed, but sugar for stimulation. The sucrose sets off the bees thinking it's nectar. The honey has already been changed to glucose and fructose and doesn't have the same stimulation effect on the bees. Also I try to feed it warm. Cool enough that you could put your finger in it and not get burned, but hot enough you'd think it was hot.