An area of lawn in my garden measuring about 30ft x 50ft has been left to run wild since 1996. I cut it once a year in late July, take the grass off and do not feed it.
The results are rather depressing, it has been taken over by coarse weeds; dandelions, nettles, buttercups, goose grass and all the usual weedy thugs. I have been reduced to using selective weedkiller to clear the nettles, otherwise I would have nettle monoculture, pulling up the goosegrass and taking the yellow dandelion flowers off before they become clocks, in an effort to make room for a wider diversity of plants, but all that does is make space for more hedgerow thugs: several plants whose names elude me, spanish bluebells and grape hyacinth.
I suspect for many of us the results will not be what people hope.