Beehives can be housed quite close together. If you move the entrance to a hive over six inches from where a bee has left the hive she may have difficulty find her way back into their hive (this shows how precise a bee’s homing is). However, this is probably not a good idea. read more
As close as you want. The photo below is a good example of hives close together. This is actually a mobile bee house in Slovenia that can be moved from field to field. read more