"Saxifrages - Which, Where and How to Grow Them", by John Morris

Saxifrages

Which to grow and where to raise them.

A few tips for those wanting to cultivate these beautiful plants.

Good drainage is essential if the plants are to survive for any length of time. The medium, whether in containers or in the open, the top 8" layer must contain 40-50% gritty components.

Container and table gardens - The typical trough will contain JI No 2/3, leafmould or peat and 3/16" grit; 25% - 25% - 50% in that order. The most suitable plants would be in the Kabschia / Englaria and Aizoon / silver sections of the genus. Species and cultivars including the following: SS. Crenata, Cranbourne, sempervivum, Cherry Trees, Valerie Keevil, Antonio, Gratioides, Whitehill, Esther, Cecil Davies and Dr. Ramsey will live happily in these conditions under partial shade. S. oppositifolia planted to hang over the side is also very effective and the purple cultivars, S. Whetterhorn and S. Splendens as well as species S. latina would do well.

Scree - Borders and raised island beds with rocky outcrops for a cool root run are eminently suitable for growing mossies and silvers, assuming that the soil meets the requirements as mentioned. The German arendsii mossy hybrids are very vigorous and providing care is taken in containing them, will form a good drift of colour in mid-spring. Other mossies to consider are the beautiful, deep red cultivar S. Peter Pan, S. Snow Carpet, S. Flowers of Sulphur, S. Winston Churchill and S. White Pixie. Medium height desirable silvers would include S. callosa var. lantoscana, S. hostii var. rhaetica, a deep wine red, S. paniculata baldensis with it's tiny rosettes and white flowers, S. paniculata lutea and any of the silvers shown suitable to be for troughs.

In an Alpine house environment, some of the higher altitude, earlier flowering species and the more challenging plants to keep are a joy to propagate and grow on. Some suitable species are those great cushions from Asia (great as in good, not large) S. lowndessii, S. georgii, S. poluniniana, S. lilacina and S. hypostoma. The Europeans consisting of, among others, S. porophylla var. montenegrina, S. media, S. marginata var. Minor, S. caesia, S. vandellii and S. tombeanensis flower along side those from Southern Spain and North Africa; further plants that need winter protection - SS. pedimontana, caniculata, erioblasta, maweana - to progress successfully.

Frames can be usefully employed in winter to protect pot grow kabschias to minimise wet conditions and to keep plants clean. Silver cushions would also benefit from glass-cover, providing air can circulate at all times. Other sections are not essentially in need of this protection.

Tufa - Most slow-growing, small rosette forming kabschias, encrusted and englarias do well growing in this medium as all limestone-loving alpine cusions plants do. Beware inserting large rosette types and keep at least 30% of the tufa rock submerged in the surrounding soil or compost.

If full sun conditions cannot be avoided, choose Saxifrages from the encrusted section for growing in this situation as the silvers are not so prone to scorching as the kabschias. Plants for open, sunny aspects can be chosen from the following: S. cotyledon Southside Seedling with its crimson blotches, S. mutata, S. longifolia [the King of the Saxifrages], S. hostii, S. cochlearis, S. cotyledon pyramidalis, S. callosa australis, all subspecies and forms of S. paniculata, especially, var. minutifolia, Lutea, Rosea, Rex and Venetia.

Shade - Plants that thrive in shade usually come from the Robertsonia and Miscopetalum sections of the genus and are as follows: S. umbrosa, S. hirsuta, S. x geum, S. urbium variegata, S. urbium Elliotts Var., S. cuneifolia, S. andrewsii, and from the Diptera section those two autumn flowering favourites S. cuscutiformis and S. cortifolia from Japan.

The Saxifrages listed here plus many more are growing with varying degress of success at Kentish Croft under the conditions described here.

Where classification is utilised, that used by Engler and Irmscher applies.

 
A Saxifrage in a clay pot
 

Saxifrages in plastic pots

Other articles by John:

  • Plants at Kentish Croft
  • Around the Benches at Kentish Croft
  • Cirumpolar Saxifrages
  • Hardy Orchids (Plant Files)