How close do the two have to be to cross-pollinate? I seem to get alot of "nearby" "close" "in proximity" when googling and my library doesn't cover this in detail either. I'm particularly interested in vibernums and apple trees. I would like to space the cross-pollinators in both instances more than 50 feet apart with one in the front and one in the back yards. Note: I have abundant bee populations. Thanks in advance. Les Newbie to Cross-Pollination
