Re Michael G's horsetail problem:-
We moved into our house 5 years ago and had major building work undertaken to both house and garden (including retaining walls to terrace the garden). During the building phase, we allowed the horsetails in the lower part of the garden to get really well established – definitely a bad move!
Once building works were complete and we got around to sorting out the garden (primarily for lawn with borders) we dug over the ground to a depth of 8 -10 inches and tried to remove every last bit of black horsetail root (as well as all the larger stones, bricks, etc.). As you'd expect, it was impossible to get every piece of root and some of them were literally feet long!
So, we still get a few horsetails popping up through the lawn, but pull them out whenever we see them. They still return, but are getting noticeably weedier (no pun intended). Some had been like thin asparagus, but we seem to have stopped them coming back. I can't imagine we'll totally eradicate them, but we're definitely winning. It is the "hoeing" principle – keep cutting them down and depleting their root energy supply. They are really sneaky though, and like to hide in the midst of other plants.
Good luck.
Tom