The genus Saxifraga, commonly called saxifrages, is vast with species found throughout the northern hemisphere. They extend from the Arctic south into the sub-tropics. We even grow some as houseplants, such as the popular strawberry geranium or strawberry begonia, botanically called Saxifraga stolonifera. The genus shows such variation that botanists, and gardeners, divide them into different groups, based upon plant habit and growing requirements. Some popular saxifrage groups are the encrusted saxifrages, the kabschia group and the mossy saxifrages. This article will specifically deal with the latter group.
Botanically, the mossy saxifrages are members of the Dactyloides group. They are characterized by evergreen rosettes of short but deeply divided, somewhat feathery leaves that lend the plants a moss-like appearance. There are about 50 species in this group but as gardeners we are only interested in the hybrids, most which have been derived from S. caespitosa, S. cebennensis, S. exarata, S. moschata and S. rosea. Many nurseries sell the hybrids as selections of S. moschata but more correctly, they should be referred to as S. x arendsii hybrids.
Saxifraga caespitosa is a native Newfoundland mossy that features in the modern hybrids
Being evergreen, the mossy saxifrages look attractive year-round. They bloom from April to June depending on your location, producing wiry stems 10-20 cm topped with a few, small saucer-shaped white, pink or red flowers. Well-grown specimens can be particularly floriferous, literally covering the plants in flowers. After blooming, shear off the old flower stems. The plants will then appear as moss-like clumps for the rest of the year. Plants covered in hoar-frost are particularly appealing in fall and winter. In the garden, use them in the shade garden, rockery or front of the border. They may even be used as a groundcover.
The mossy saxifrages are generally care-free with few pests or diseases. They thrive in semi-shaded, moist sites but will not tolerate hot, dry conditions. They are rated for zones 5 to 8. In cooler-summer regions, mossy saxifrages will tolerate full sun if kept moist but the plant risk burning in winter if snow cover is not adequate. The hybrids may be grown from seed although they may not breed true. Named varieties are easily propagated by softwood cuttings taken just after blooming or by dividing larger plants.
Some modern-day hybrids inlcude 'Flower Carpet' (top left), 'Red Robe' (top right), 'Snow Carpet' (bottom left) and 'Elf' (bottom right)
There are many named hybrids, differing only subtly from each other based on flower shade or plant height. Some of the more popular cultivars include 'Purple Robe' (carmine-red with 15 cm stems), ‘Flower Carpet' (more correctly known as ‘Blutenteppich'; carmine-pink fading to light pink on 15 cm stems), 'Peter Pan' (carmine-red with 10 cm stems). 'Elf' (carmine-red on 5 cm stems; late flowering), 'Triumph' (dark red on 15 cm stems) and 'Snow Carpet' (more correctly known as ‘Schneeteppich'; white flowers on 15 cm stems). A final cultivar of particular note is 'Bob Hawkins' whose leaves are edged in white lending a frosted appearance all year long. It has white flowers on 15 cm stems.
Details of 'Bob Hawkins'
I would like to thank DaylilySLP for the use of 'Purple Robe' and saya for 'Snow Carpet'.