Leaves Are Important
Think of plants with lovely leaves and most gardeners imagine trees, shrubs and fabulous autumn colour. Perennials are rarely considered yet many have beautiful leaves and this very important attribute should certainly be given some thought when choosing what to grow especially for winter colour.
Although the majority of perennials are herbaceous - which means the leaves die right back in autumn, reappearing again in spring - some perennials keep the leaves all year. More often than not these evergreen perennials form low, spreading mounds, whcih makes them incredibly useful for narrow borders and the edges of border. Also, because the majority of evergreen perennials don’t mind a certain amount of shade it won’t matter to the plant if taller plants tumble over them. For instance I grow a lovely form of our native Bugle Ajuga reptans ‘Catlin’s Giant’ (height and spread: 15cm x 30cm) in front of Alchemilla mollis. This plant tends to romp over other, but the Ajuga’s shiny, rich mahogany leaves still manages to survive the onslaught. Along side this plant I grow the once popular Saxifraga x urbium (London's Pride) (height and spread: 45cm x 60cm), which I am pleased to say is gaining in popularity as gardeners search for easy-to-grow, reliable plants. Another lovely evergreen perennial is the classic rock garden Rock Rose Helianthemum ‘Wisley Pink’ (height and spread: 20cm x 25cm). The small, soft green leaves form a small mound and combination prettily when planted next to Dianthus ‘Devon Wizard’ (height and spread: 30cm x 45cm) with grey, needle-like leaves. Add a dramatic touch of contrast by allowing the black leaves of Ophiopogon planiscapus ‘Nigrescens’ (Black mondo grass) (height and spread: 20cm x 30cm) to tumble amongst them. By the way this is not actually a grass, its a member of the asparagus family.
For a big, bold winter colour select perennials with large, leathery leaves. These will create all-year-round architectural form. My evergreen favourites are Elephants ears, in particularly Bergenia ‘Eroica’ (height and spread: 30cm x 45cm) as the large, spatula-shaped leaves turn rich red in autumn, a colour that last into early spring when the new leaves start to emerge. Hellebores are essential for winter colour, but not all are evergreen. One that is is the Helleborus argutifolius (Corsican hellebore) (height and spread: 90cm x 75cm). This marvellous plant has big, finger-like, dark green leaves that form heaped mounds. A plant with much smaller but equally beautiful leathery foliage is an orange flowered Epimedium x versicolor ‘Orangekonigin’ (Bishop’s Mitre) (height and spread: 45cm x 60cm). This, like Bergenia and Helleborus is happy growing in almost full shade as is Iris foetidissima (height and spread: 45cm x 45cm). Known as the stinking iris because of the strange roast beef aroma of the roots, this shade loving iris is rarely grown for the rather dull flower, but more for the dark green leaves and handsome orange seeds that are revealed when the pods split open in late autumn.