how about lavender? you can get different colours as well, i had a white one which smelt lovely.

As it faces North, knowing which part of the country you're in would be very helpful. North facing in London is a very different thing from North facing in, say, Leeds.

I grow hostas, aqualegia and various geraniums - the perennial type and they all thrive in a north facing border. You are right about roses, I have a climber which reaches the roof every year and has to be hacked back ruthlessly.

I have two north borders.Nothing as tall as you want though. I have two varieties of variegated euonymus fortunii, alchemilla mollis, lily of the valley, a red euphorbia robbiae whose name I forget (doesn't run) and an omphaloides. In the spaces I put annual begonias and daffodils. At the ends there's a pieris, an azalea and a skimmia.

Here's a few ideas - dicentra spectabilis (bleeding heart), solomon's seal, honesty (a biennial), astrantias, campanula trachelium, and for later colour phlox