Posted: 19/11/2013 at 17:05
I have a very exposed garden that gets colder than Yourkshire so can recommend a few clematis. You can check their details - flower, size, pruning group on this site - http://www.clematis.hull.ac.uk/
Nelly Moser; Rhavarinne, Blue Angel (Blekitny Atholl), Alba Luxurians, Omoshiro, Huldine, Etoile Violette, Little Nell, Princess Diana, Red Ballon, Red Robin, Arabella, Chrystal Fountain.
For perennials, have a look at phlox, echinops, aconitums, phlomis, chelone, hemerocallis, hostas, grasses such as hakonechloa, miscanthus, carex, molinia, asters, physostegia, astilbes, Japanese anemones, peony...
For shrubs, have a look at coloured stemmed cornus such as alba sibirica and Midwinter fire. They need to be pruned back hard every spring or two to maintain tehir colour so won't get too big. Consider evergreens such as variegated holly which is slow growing and can be pruned to shape.
Go and have alook at Harlow Carr for ideas and get a soil test kit so you know whether the soil is acid, neutral or alkaline. Add plenty of well rotted garden compost or manure too improve fertility and drainage then get planting. Bit late this year but don't forget bulbs like snowdrops and daffs for early spring colour.