Some gardens and landscapes are works of art that deserve to be left to posterity. But unlike an oil painting of an enigmatic smile or a stainless steel sculpture of a balloon dog, their changeable nature makes them tricky legacies.

Owners get a buzz out of adapting their garden after a feature tree falls, an obelisk crumbles, a gnome escapes, a stream decides to dry up or a pivotal plant variety succumbs to disease. But faced with the same problems, what should an inheritor do? Should inheritors stick to the garden’s design and original planting? Should donors impose conditions? How should inheritors deal with benefactors’ wishes?

Plas yn Rhiw, a pretty one-acre garden overlooking Cardigan Bay in Wales, was given to the National Trust in the mid-20th century on condition that, among other things, the wild bees should not be disturbed and the yew and box hedges should be preserved. The former condition is fine — admirable even — but the latter is tricky as box is victim to three types of blight, Phytophthora root rot and Box tree caterpillar — to say nothing of various scale insects, red spider mite?.?.?.?you get the idea.