How about a liberal installation of wire hoops in the nettle patch - about
6 or 8 inches high ought to do it.

After the 15th time of having to reset the strimmer cable because it's
broken on the hoop he might give up on it... (unless it's an auto-feeding
strimmer... my memory seems to suggest that such beasties do exist).

--
Richard Sampson
what a brilliant ides thanks :-)))