A large genus of small alpine and woodland plants that are native to various parts of the globe. They differ greatly in flower, foliage and form but the majority of garden varieties either form a spongy cushion of leaves or a mat of leafy rosettes; above which a mass of tiny red, pink or white flowers appear in summer.
Botanical Name: Saxifraga
Common Names: Rockfoil
Foliage: Small simple or palmately lobed, green leaves, in tight cushions or rosettes of evergreen leaves.
Flowers: Five-petalled white, yellow or pink, star shape or round flowers.
Flowering Period: Spring to early summer.
Soil: Moist but well-drained soil (sand, chalk, loam) Alkaline to neutral pH.
Conditions: Full sun or partial shade (depending on variety). Grow in a south, east or west facing aspect, in a sheltered location. Protect from winter wet.
Habit: Compact, cushion or mat-forming.
Type: Evergreen or herbaceous perennials.
Origin: Europe, Asia, and North and South America,
Hardiness: Fully hardy in most regions of the UK.
Most varieties should be planted out in early autumn or late winter.
For the best results grow in moderately fertile, well-drained alkaline (chalky) soil, in full sun or semi-shade. Incorporate horticultural grit at planting time to improve drainage.
They do well at the front of the border or rock gardens. Also suitable for alpine troughs, raised beds, pots and containers or in an alpine house.
Keep roots moist in summer but protect from winter wet.
No pruning required. Trim off faded flower heads.
Susceptible to aphids, slugs, vine weevil and red spider mite. Generally disease free.
Sow seed in the spring or take offsets in the winter. Mature clumps can be divided in the spring.
Saxifraga is a large genus of plants, covering a numerous and varied species, with a great number of hybrids. Some of the core garden species include:
Euaizoonia (Aizoon) (Encrusted or Silvery Saxifrages) are ideally suited to limestone rocks but will grow almost anywhere if given a very free draining soil and a warm, sunny situation.
Dactyloides (Mossy Saxifrages) require a well-drained soil, (gritty loam or sand) and do best in a cool position in semi-shade.
Kabschias ("Cushion" or Tufted Saxifrages) required an open and fairly sunny site, facing east or west. The soil must be moist but well drained. Protect plants from winter wet with a sheet of glass or Perspex.
Porphyrions require a cool position in partial shade and a well-drained compost of moist, gritty loam and leaf-mould.
Diptera are best planted in an alpine house or a sheltered situation in the rock garden. Plant in a light gritty loam.
Robertsonia prefer a shady position, in a light, gritty loam.
Trachyphyllum are semi-shade loving and do best in a moist, gritty loam.
S. burseriana is a dainty cushion saxifrage with white flowers in early spring. Height to 2in (5cm). Slow growing. Ideal for an alpine trough.
S. cuneifolia-variegata is a dwarf form with dainty sprays of white flowers in early summer. Height to 6in (15cm), spread to 1ft (30cm).
S. 'Knapton Pink' is a hardy reliable alpine that produces a neat mossy cushion of green foliage. Bright pink flowers are borne above the foliage in Spring. Height to 6in (15cm), spread 12in (30cm).
S. 'Lutea' (paniculata) produces a rich carpet of green rosettes topped with sprays of small white, pale yellow or pink flowers, from late spring to early summer.
S. Moschata forms a neat hummock of olive-green rosettes, topped with flowers in all shades of pink during the Spring. Height to 2in (5cm), spread 10in (25cm).
S. Moschata 'Cloth of Gold' produces a cushion of golden mossy foliage, topped with pearly white flowers in the Spring. Height to 2in (5cm), spread 10in (25cm).
S. 'Peter Pan' is a small compact variety that produces a mossy mound of green foliage, topped with small pinkish-red, starry flowers in early summer. Awarded the RHS Award of Garden Merit. Height and spread to 10in (25cm). Available at Thompson & Morgan.
S. 'Splendens' (purple mountain saxifrage) produces cushions of small leaves covered by tiny white, yellow or pink flowers in early summer.
S. Saxony Red is a mat forming evergreen perennial with glossy grey/green foliage that provides bright red to deep pink flowers in the Spring. Height to 4in (10cm), spread 12in (30cm).
S. Umbrosa Variegata forms a mat of compact rosettes of dark green leaves, variegated with a tinge of yellow. Sprays of pretty pink flowers on tall stems appear in late spring. Height to 1ft (30cm), spread 1.5ft (45cm).
S. x urbium (London pride) has rosettes of oval shaped green leaves, covered by masses of small pinky-white flowers on wiry stems in early summer. Height to 12in (30cm).