I had a big bleeding heart that had been in it's spot for years that I had to move in late April due to some construction. We just dug it up as best we could and stuffed it into a large planter box where it sat for a couple of months till I could relocate it. It didn't do much the following year, but it has survived and continues to improve, and that was with some very rough treatment. It would, of course, be best to wait till it goes dormant, but if that's not possible, just dig up as much of the roots as you can and have the new spot dug and ready to receive it. Unless, as Sally mentioned, it's just a baby. Ours was huge.
