Dynamic tree shadows

I'm making a game (which takes place in a forest) and I need a day/night cycle, but that won't work with lightmapping (only way for trees to have shadows). I need tree shadows, otherwise the forest will just look broken, and pre-making shadows with texturing the terrain will still look bad (when the light is coming from the same direction as the shadow is going).

Is this a Unity Pro only feature? If it, are there any good alternative solutions? I can't really afford unity pro, so a good alternative (that's NOT manually replacing all the trees, which would be bad for performance and a real pain) is kind of important.

EDIT: Okay, this is odd, in a different scene dynamic tree lighting is working fine. I think I might've made a mistake somewhere...?