There's a general prohibition to cut down fruit trees (see this question), based on 'bal tashchis'. Would the prohibition apply even to fruit trees that are expensive to maintain (and do not produce ...
If you move a tree with its soil, it's considered replanted (so the rules of orla kick in) unless it can live off of the soil you're moving it with. (Source.) Clearly "if it can live" doesn't mean "if ...
Can one say Birchas Ilanos on a fig tree?
I haven't studied Tractate Kilayim. I know you can't plant grapes with wheat. What about, say: Jazz apple = Royal Gala apple X Braeburn apple ? Nectarine = Peach X Plum ? Nectaplum = Nectarine X ...