When I read, so very often, suggestions that we should leave our gardens go a little wild, should allow the wildflowers (weeds!) grow in the lawn etc I feel it is a very misplaced suggestion when directed at a rural garden. There are about two miles of wild hedgerows between our garden and the beginnings of town and all around I am surrounded by farmland with boundaries of native trees and plants. In this context, the non-native plants I grow in the garden are the ones introducing biodiversity as I am growing a selection of plants which would otherwise not exist in my area. So, in my case, I will leave the wild be wild and my garden be gardened in the traditional manner.
Look at these wasps enjoying the flowers of Camellia sasanqua in mid-November, an introduced plant, a non-native, supplementing the native species and increasing biodiversity: