Neglect.

Across the wall at the end of my garden.
This was a lovely garden a couple of years ago, as are the vast majority of gardens around here.
Then the old man died and the house was sold for rental. Neither the landlord nor the new tenants seem to be the slightest bit interested in keeping it in any kind of order.
It's such a shame.
There are many who would kill for a garden that size.