In article , Janice
writes
When is the best time to severely cut back cotoneaster horizontalis?

Whenever you spot it ;-)

I thought about pruning it last spring, after it had flowered, but I didn't
want to lose the berries. But if I cut it back now then I'll lose the
berries now as well as next year's flowers anyway, right?

a) Depends how far you cut back and b) no
It flowers on wood that is at least two years old. Once the wood is old
enough to start flowering, it will carry on doing so.
So if you simply cut back all the new growth, you won't lose any
berries, and although you won't get the flowers that would have appeared
next year on the new growth, you will get all the flowers that were
going to appear on the older wood.

If you need to cut it back further than that, you will obviously lose
any berries that you cut off, but, once again, you'll keep all the
berries on bits you haven't cut, and will continue to get flowers on
those.

In a few years time, it will have spread over so much of your garden,
that you won't worry so much about losing bits of it ;-)


And, it will grow back after a SEVERE pruning, right?

Yes.
--
Kay Easton

Edward's earthworm page:
http://www.scarboro.demon.co.uk/edward/index.htm