Gardening

Well, the privet has to go, and if I were you--given his history--I'd put in some nice paver stones and pots of plants you know he can tolerate. I wouldn't plant anything into the ground for at least a year to make sure he is absolutely not allergic to the plants in pots. With pots, you can do elimination testing if he does react, and it's a lot easier to ditch a potted plant--or find it a new home--than to dig something up.

You could do herbs, flowers, even small trees. Pots would also give you the opportunity to try out different landscaping arrangements, plus it's easier to care for potted plants.

I do not envy you (or him); serious allergies are a dreadful, miserable problem. Good luck!