in article , Charlie Pridham
at wrote on 9/2/03 11:51 am:

snip

Trewithen Blue is a good clone of C. arborea and is not a good hedging plant
if you are going to leave it to do its own thing, mine (I have 3) are 20-25'
high and across, when I prune I use a chain saw, the main trunks are 12"
across.
They can however unlike most ceanothus be cut back hard into old wood (hence
the recomendation)

Didn't the OP want something to grow in front of a fence, though? Not
actually to be a hedge acting as a barrier. I think the effect is required
to be decorative, rather than protective.
--
Sacha
www.hillhousenursery.co.uk