In principle, plants thrive in situation that is more relate to their original habitats. The most suitable plants are those in woodland settings. It does not mean hot climate species can not survive. These can go on the wall, or pots.
January: Cotoneaster simonsii berries
February: Galanthus navalis
March: Ranunculus ficaria
April Magnolia 'Red Lucky'
May: Papaver cambricum
June: Lavandula angustifolia
July: Lysimachia nummularia 'Aurea'
July: Galanthus
August: Lavatera
October: Chrysanthemum
November: Betula pendula 'Snow Queen'
December: Pyracantha