In article , Barton
Bloggs writes
When is the best time to prune back an overgrown cotoneaster horizontalis?
Now or wait until spring?

Also, can it be cut back really hard or should it only be pruned lightly?

It can be cut back as hard as you like. It's indestructible.
Remember it berries on 2nd year wood - it won't have berries next winter
on anything it grows over the summer, so you might want to remember this
as you decide what to cut.

I didn't cut it back earlier because I wanted to leave the berries for the
birds, but now the berries are gone.

Our birds leave it till last, and in most years don't get around to it
at all.
--
Kay Easton

Edward's earthworm page:
http://www.scarboro.demon.co.uk/garden/