How to Grow Saxifraga
From the Latin saxum, rock or stone, and frango, to break, alluding either to its ancient medicinal use for ‘breaking’
Saxifrage, rockfoil. A genus of some 370 species of mainly dwarf tufted perennial and annual plants inhabiting the mountain regions of the northern and southern temperate regions. The many species, varieties and cultivars are usually grown on the rock garden or in the alpine house.
For the convenience of classification, the genus is divided into 15 or 16 sections, largely on the basis of the characteristics 1 of its foliage and habit. From’ the gardener’s point of view, however, it is best divided as below into fewer larger groupings according to cultivational requirements.
Species cultivated S. aizoides, yellow mountain saxifrage, a loosely tufted mat-forming species with yellow, orange or red flowers and linear fleshy leaves. S. aizoon (see S. paniculata). S. apiculata (S. marginata x S. sancta), a cushion or Kabschia hybrid, forming wide mats of green, silver-tipped rosettes and primrose-yellow flowers on 3-inch stems. S. x arcovalleyi (S. burseriana x S. lilacina), a Kabschia hybrid with compact silvery cushions and soft pink flowers on 1-inch stems. S. aretioides produces hard, grey-green cushions and yellow flowers; a Kabschia that has given rise to many good hybrids easier to grow. S. x assimilis (probably S. burseriana x S. tombeanensis) has firm grey cushions and white flowers on 1-2-inch long stems. S. biternata is an ally of the meadow saxifrage from the Mediterranean area. It has tufts of hoary, kidney-shaped, divided leaves and large glistening white flowers on 6-8-inch long stems. S. x borisii (S. ferdinandicoburgii x S. marginata) is a Kabschia hybrid with blue-grey cushions and large citron-yellow flowers on 3-inch stems. S. boryi, allied to S. marginata, but more compact in habit. S. x burnatii (S. paniculata x S. cochlearis) is a silver or encrusted hybrid showing a blend of the parental characteristics; white flowers in loose panicles are borne on reddish stems. S. burseriana is the finest of the Kabschias and a parent of many excellent hybrids and cultivars. The type plant forms large cushions of crowded, silver-grey rosettes composed of many narrow, somewhat spiny, leaves. Each rosette bears a 2-inch long reddish stem surmounted by one or more large glistening-white flowers in early spring. S. b. ‘His Majesty’ is a splendid form with the flowers flushed pink; S. b. ‘Gloria’ has larger flowers on redder stems; S. b. sulphurea may be a hybrid, but looks like the type plant with soft-yellow flowers. S. cespitosa (syn. S. caespitosa), tufted saxifrage, is one of the `mossy’ species and a rare native in Wales and Scotland. It makes dense cushions of somewhat glandular, hairy, deeply divided leaves and bears small white flowers on short slender stems. S. caucasica is a green-leaved Kabschia with yellow flowers on 1-inch high stems. S. cernua may be likened to a mountain form of the meadow saxifrage (S. granulata) with a drooping inflorescence bearing both white flowers and red bulbils in the leaf axils. It is a very rare Scottish native. S. cochlearis is an encrusted species, with small spoon-shaped silver leaves forming the hummock-like plants, from which arise slender panicles of milk-white flowers on reddish glandular stems. S. c. minor and major are smaller and larger forms. S. cortusifolia belongs to the Diptera section, to which the better known S. fortunei belongs, and has rounded, deeply-cut leathery leaves on stiff 3-inch long stems and panicles of white flowers with irregularly-sized narrow petals. S. cotyledon is one of the largest encrusted species, with broad rosettes of wide strap-shaped leaves rimmed with silver and huge airy panicles of white flowers that may be 11-feet or more long. S. c. caterhamensis and `Southside Seedling’ are superior forms with red-spotted flowers. S. crustata, also an encrusted sort, is smaller, the rosettes forming cushions or mats with off-white flowers on branched 6-inch stems. S. cuneata is a loose ‘mossy’ species with toothed, deeply-lobed, leathery leaves and open panicles of white flowers. S. cuneifolia belongs to the Robertsonia section whose chief representative in gardens is London pride (S. umbrosa). It is a’ small species with flat rosettes of leathery daisy-like leaves and flowering stems reminiscent of London pride in miniature. S. cuscutiformis is a smaller edition of mother of thousands (S. stolonifera) with the leaves prettily veined white. Abundantly produced red stolons, or runners, resemble the leafless stems of common dodder (Cuscuta). S. cynzbalaria is an annual, with smooth shining kidney-shaped leaves and numerous starry yellow flowers. S. decipiens (see S. rosacea). S. x engleri (S. crustata x S. hostii) resembles the first parent, and has pink flowers on 3-inch stems. S. exarata is a distinctive ‘mossy’ saxifrage, with dark green, strongly-nerved, deeply-cleft leaves, and flowers that may be either white, yellow or purplish. S. ferdinandi-coburgii belongs to the encrusted group, forming neat mounds of silver-grey, spiny-leaved rosettes topped by 4-inch high stems bearing red buds and bright yellow flowers. S. x florariensis (S. hostii x S. lingulata) is an encrusted hybrid eventually forming mats of handsome 3-inch wide, silvered
rosettes that turn red in autumn, and have foot-long sprays of white flowers. S: fortunei is undoubtedly the finest member of the Diptera section, with large, glossy, thick-textured, kidney-shaped leaves which are often red beneath, and tall airy, elegant panicles of glistening white flowers, each with one or more extra long tail-like petals. The plant is completely deciduous after the first severe frost of late autumn. S. x frederici-augusti (probably S. media x S. porophylla) is a hybrid in the Engleria section, noteworthy for the flowering stems being clad in leafy often coloured bracts. This hybrid has silver-rimmed rosettes and flowers composed of a bell-shaped calyx covered with claret hairs below the small 1 pink petals. S. geum (see S. hirsuta). S. x 2 godseffiana (S. burseriana x S. sancta) produces mats of narrow spiny-leaved rosettes and lemon-yellow flowers on reddish stems. S. granulata, the meadow saxifrage of Britain and also known as fair maids of France, is a deciduous species, the kidney-shaped, rounded-toothed leaves dying away soon after the plant has flowered; milk-white flowers are borne on branched stems up to 1 foot tall; var. plena has double flowers. S. grisebachii belongs to the Engleria section, eventually forming humped mats of 3-inch wide grey rosettes set with leafy flowering spikes 9 inches tall. The bell-shaped calyces and bracts are set with deep red glandular hairs. S. x haagii (S. ferdinandii-coburgii x S. sancta) is a Kabschia with dark green rosettes in cushions and bears rich yellow flowers. S. hederacea rather resembles a small creeping Linaria or Cymbalaria, with small ivy-shaped leaves and starry white flowers. S. hirculus is placed in a section of the same name, and forms tufted mats of narrow leaves and branched stems set with quite large yellow flowers speckled with orange. It is a rare British native and known as yellow marsh saxifrage. S. hirsuta, probably better known as S. geum, is a Robertsonia saxifrage akin to London pride, but with longer leaf stalks and rounded leaves heart-shaped at the base, set with long hairs on both surfaces. The flower stems, covered with short hairs, support open panicles of small white blossoms, each petal bearing a yellow spot at its base. S. hostii is one of the finest encrusted species, forming wide mats of silvery rimmed rosettes set with creamy-white flowers in short corymbs. S. huetiana is a small bushy annual with starry yellow flowers freely produced. S. hypnoides, Dovedale moss, is a cushion or mat-forming mossy species native to Britain and most of the hilly regions of the northern temperate zone. It is very variable in habit, flower size and colour, the type being white; var. condensata is very compact with yellow flowers.; var. kingii is close-growing, the leaves turning red in winter; var. purpurea has reddish flowers. S. x irvingii (probably S. burseriana x S. lilacina) was raised at Kew Gardens and is one of the
S. stolonifera (syn. S. sarmentosa), mother of thousands, has long red, branched runners like those of a strawberry, large round marbled rather fleshy leaves and graceful panicles of white flowers spotted with yellow and red. Typical of the Diptera section, each flower has one or two extra elongated petals. S. trifurcata belongs among the ‘mossy’ species with deeply cut recurved leaves somewhat aromatic when bruised and 6-inch stems of large white flowers. S. umbrosa is akin to S. spathularis but with shorter, long-hairy leaf stalks and the leaf blades with a cartilaginous border. S. valdensis is similar to, but smaller and slower growing than, S. cochlearis, with stiff glandular stems surmounted by heads of round white flowers. Cultivars: ‘Amitie’ (S. lilacina x S. scardica obtusa) is a Kabschia with firm cushions of grey-green rosettes and lilac flowers on 1-inch stems. ‘Apple Blossom’ (mossy’ hybrid) has small pale pink flowers in profusion. ‘Boston Spa’ (Kabschia hybrid) bears deep yellow flowers with red buds over green cushions. ‘Buttercup’ (Kabschia) has rich yellow flowers on grey-green cushions. ‘Cecil Davies’ (S. lingulata x S. longifolia) has very compact mounds of silvered rosettes and elegant sprays of white flowers. ‘Cranbourne’ is probably the finest of the Kabschia hybrids with neat grey-green mounds of 0.5 inch wide rosettes and almost stemless large clear pink flowers. ‘Dr Ramsay’ (S. cochlearis x S. longifolia) is an encrusted cultivar with symmetrical silvered rosettes and sprays of white flowers on 1-foot stems. ‘Edie Campbell’ and ‘Elf’ are both ‘mosses’, the former with large pink flowers in profusion, the latter smaller and neater. ‘Ester’ (S. paniculata lutea x S. cochlearis) bears soft yellow flowers in short sprays over vigorous masses of silvered rosettes. ‘Faldonside’ (S. aretioides x S. marginata) is a first-rate Kabschia with citron-yellow flowers, the overlapping petals of which are charmingly crimped at the margins. `Gem’ (S. burseriana ‘Gloria’ x S. irvingii) is another good Kabschia with neat blue-grey spiny mounds and pale pink flowers with a ruby eye. ‘Four Winds’ is a rich red ‘mossy’ sport. ‘Iris Pritchard’ (S. x godroniana x S. lilacina) bears flowers of apricot-rose over neat grey hummocks. `James Bremner’ is one of the few good white-flowered ‘mosses’ and aingscote White’ is a larger flowered pure white `mossy’ variety. ‘Kathleen Pinsent’ (encrusted) may be a S. ligulata x S. callosa hybrid, with 1-foot long stems and sprays of yellow-eyed pink flowers. ‘Myra’ (Kabschia) is probably an S. lilacina hybrid, with compact, slow-growing mounds of silvery rosettes and deep pink blossoms. `Mrs Piper’ (`mossy) forms wide mats of soft green foliage studded freely with bright red flowers on 3-inch stems. ‘Pearly King’ is a similar ‘mossy’ with pearly-white flowers. ‘Pixie’ is a compact growing `mossy’ with rose-red flowers. ‘Riverslea’ (S. lilacina x S. porophylla) is a Kabschia x Engleria hybrid, with silvery rosettes in compact mounds and purple-rose flowers on 3-inch stems. `Salomonii’ (S. burseriana x S. marginata) produces free-growing silvery mats and 3-inch stems bearing large vase-shaped white flowers that are pink in bud. ‘Sir Douglas Haig’ (mossy’) bears dark velvety-crimson flowers. `Southside Seedling’ is a comparatively new S. cotyledon hybrid with large silver-rimmed rosettes and long sprays of white, intensely red-spotted blossoms. ‘Tumbling Waters’ (S. lingulata x S. longiflora) is the finest large encrusted hybrid with huge silvered rosettes and magnificent 2-foot long plumes of white blossoms. ‘Winston Churchill’ (mossy’) bears soft pink flowers on 6-inch stems.
Cultivation With the exception of species in the section Hirculus, a few of the `mossy’ group, and S. aizoides, which need moist to wet conditions to thrive well, practically all saxifrages require a well-drained site either on the rock garden, dry wall, raised bed, moraine, or in pots and pans in the alpine house. The Robertsonia species, typified by London pride, the Miscopetalum section, and such species as S. hederacea, require a shady site, the first mentioned doing particularly well even in complete shade or in woodland. Kabschia species require particularly good drainage and are best grown in a scree or raised bed. Flowering very early, they are ideally suited to alpine house culture where their delicate-looking flowers may be appreciated unsullied by heavy rain and mud splash. Most of the encrusted group are ideal for the open rock garden, in rock crevices or dry walls; S. cotyledon and longifolia should always be grown in the latter habitat if at all possible. All the popular mossy hybrids and some of the species are good all-rounders on the rock garden and are also suitable for paved areas and as ground cover for small bulbs. Generally speaking they will stand partial shade well and seem to thrive better if the site is not too sun drenched. Propagation is effected by seeds sown in pots or pans in early spring, stood in a cold frame, by division after flowering, or by offset rosettes inserted as cuttings in a sand frame from spring to late summer.