Posted: 28/06/2012 at 09:10
We have a deep north facing border. At the back are climbing roses, some are fine with less sun, honeysuckle, clematis montana, pyracanthas for colour when the berries are out, ceanaothus for blue in spring, woodland type bulbs are fine. Forget me not was a lovely splash of blue a month or so ago. Hardy geraniums. I finally got a japanese anemone established there for tall pink flowers in autumn, but I'm not sure how well it will flower yet. Same with aquilegias, I've got them established finally, but they probably flower more in sun. I'm trying some thalictrum aquilegifolium but it's not that colouful.
Most of the spring colour in ours somes from camellias, azaleas & dwarf rhodedendrons, but your soil has to be acidic for them. In the autumn a lot of colour comes from asters.
Clematis is a great splash of colour, but slugs have eaten every variety I've tried, except the enormous montana. Nelly Moser is good in shade, with pretty pink stripes.
If the border is large enough, small maples can give great colour with their foliage.
I always think there are a lot of shade tolerant plants, but looking at the reply above we both have lots of the same plants, so there are definitely some more commonly used ones.