Rock garden plants with attractive foliage are especially important in small gardens where we aim to encourage the longest and most colourful display. Expert Graham Rice offers some suggestions
Rock and alpine plants mostly flower in spring with some flowering in autumn. Appealing foliage may add to the floral display, or it may be the main point of growing the plant, bringing us colour and interest for many months. Either way, we shouldn't forget foliage plants for rock gardens, raised beds and troughs.
Some of these choices are for the familiar rock plant conditions of sun and good drainage, but others are ideal for cooler and shadier places at the back of raised beds or shaded by fences where so many sun-loving rock plants are unhappy. As ever, all of my choices have received the RHS Award of Garden Merit.
H1 - H7 indicated the new hardiness ratings
Full details of hardiness ratings (510kB pdf)
The yellow-leaved form of creeping Jenny, Lysimachia nummularia ‘Aurea’, is just about the lowest-growing creeper you can find. Its slender stems spread out flat, rooting as they go, shining yellow in spring and summer with upturned yellow summer flowers. It's best grown in dappled shade or shaded by a fence or wall where it will run around in less than choice conditions bringing a sunny brightness. It'll also recover well from summer drought. 3cm (1in). H5.
This is a bushy, upright plant with tiny, pale green, lemon-scented leaves making a twiggy, rounded little bush in well-drained, sunny or slightly shaded conditions. Each leaf is edged in white and in summer the shoots are topped by tiny pink flowers. This is a delightful plant and ideal not only as an evergreen in raised beds and deep troughs, but as a culinary herb; its flavour is excellent. 15cm (6in). H5.
The bold, and pleasingly symmetrical, purple rosettes of Sempervivum ‘Othello’ are slightly smoky-purple in the centre. Each succulent leaf broadens before narrowing to a pointed tip. It's ideal in gravel gardens, amongst rocks, in shallow pots or even on roofs, the traditional home of the houseleek. Each rosette produces a spike of starry pink summer flowers before dying and being replaced by new rosettes on short runners. 15cm (6in). H5.
Where you need a creeping evergreen with character for a shady corner where the drainage is good, then Blechnum penna-marina is a good choice. This antipodean relation of our native hard fern steadily expands to form clusters of glossy arching fronds. These mature from pale to dark green, sometimes bronze tinted. Each is split into opposite pairs of short lobes. An ideal partner for erythroniums and wood anemones. 15cm (6in). H4.
The trailing stems of the succulent Sedum spathulifolium ‘Purpureum' can spread 4 or 5 times the height of the plant. Each rather fragile stem carries rounded, fleshy, reddish-purple leaves formed into rosettes towards the tips. Occasionally rooting as they go, the mass of stems makes an attractive feature in a well-drained sunny place boosted by starry yellow flowers in late summer. It's happy on chalk and in pots. 10cm (4in). H5.
Silvery evergreens are invaluable, especially if they remain reasonably small, and Hebe recurva ‘Boughton Silver’ does exactly that. It makes a bushy plant, more wide than tall, with narrow, pointed, blue-tinted silver leaves about 5cm long. In late summer and autumn, bright showy spikes of small white flowers emerge from the upper leaf joints creating a pale harmony of shades. Ideal as a specimen in a well-drained raised bed or in a container. 60cm (1ft11in). H5.
A delightful ferny creeper for the back of the rock garden is the British native oak fern, Gymnocarpium dryopteris. Superficially, it resembles many ferns with triangular fronds divided twice into opposite pairs of leaflets. But its colour remains bright, fresh-green from spring to autumn and it takes drought once established. It spreads consistently in humus-rich soil but if it threatens to overwhelm other treasures it's easily removed. 20cm (8in). H5.
Don't let the lengthy name put you off – this is a superb little plant, and another that features lovely foliage to carry colour through much of the year after its winter flowering. The flowers are white, with a deep purple mark at the base of the upswept petals. The rounded leaves are almost entirely silver and fade away in summer. 7cm (3in). H5.
Aubrieta is one of the easiest and most popular spring flowering rock plants but when the flowers are over, it looks rather dull. The spreading plants of Aubrieta ‘Argenteovariegata’ have vivid, pinkish-purple flowers which make a vivid contrast with the silver-edged, pale green leaves. The leaves are evergreen so provide colour all year. The yellow edged A. 'Aureovariegata' has also been awarded the AGM. Both are less vigorous than green-leaved forms. 7cm (3in). H5.
We usually think of maidenhair ferns as house plants but a few are perfectly hardy outside. A. ‘Subpumilum’ is a form of the steadily spreading Adiantum aleuticum with fan-shaped fronds split into ring of long segments with purple midribs, each lined with opposite pairs of small leaves. It's very low growing, but its fronds overlap and interknit to provide a delightful carpet in full or dappled shade. It appreciates good drainage. 5cm (2in). H5.