In article , H
writes
in a neighbouring garden. Having pruned said conifers to 7ft high I
followed advice to hammer pure copper nails into the tops of the trunks

Maybe you should have hammered nails into just half of them .. and see if
there was a difference 6 months later.

And hammered placebo nails into another half...
Hold on that's 3 halves, that can't be right
--
David