(Editor's Note: This article was originally published on May 5, 2008. Your comments are welcome, but please be aware that authors of previously published articles may not be able to promptly respond to new questions or comments.)
Most gardeners will tell you that African violets are very tender plants...the slightest touch of cold and they rapidly shrivel. However, believe it or not, there are African violet relatives that are hardy to zone 4, even 3 with winter protection! These gesneriads (the term used to encompass those members of the Gesneriaceae or African violet family) are not native to the tropics like the vast majority of gesneriads. Instead, they hail from high elevation, steep alpine cliffs of the Mediterranean region. For rock gardeners these hardy gesneriads are the ‘Rolls Royce' among alpine plants. The genera include Ramonda, Haberlea and Jankaea.
In the wild, they often grow on north-facing vertical cliffs where moisture quickly drains away from their evergreen rosettes. Winter is the wet, cold season and plants may be frozen for several months. Summers are hot and dry but these plants grow on north-facing cliffs so are never exposed to the burning rays of the sun. Plants often grow where there is some seepage so plants remain reasonably moist even in summer. In the garden a north-facing rock wall is ideal. Planted in this way you are duplicating they way they grow in nature. I must confess, I grow my Ramonda and Haberlea on the level. However, my site is very well drained and only receives early morning sun. They are snow-covered for at least 4 months (I told you they are tough!). I also grow some in pots kept outside on my shaded deck in summer and overwintered in my coldframe. The main key to success is to not allow them to stay soggy wet in winter yet keeping them evenly moist in summer. Plants will curl in their leaves if too dry. With watering, they will plump-up again but if this cycle is repeated too often, brown leaf edges will result.
Both Ramonda and Haberlea will easily survive zone 5 (I've grown them for years in my zone 5 garden), possibly colder if there is adequate winter protection. I know gardeners in Calgary, Alberta, Canada who grow these outside in their winter-dry zone 3. Jankaea on the other hand, is rather temperamental and only hardy to zone 7. I keep mine in my unheated basement in winter (just above freezing).
The genus Ramonda contains three species; R. myconi, R. nathaliae and R. serbica.. Their flowers are the most similar to African violets. The standard colour is mauve-purple but white and pink forms exist. They bloom in late spring-early summer in my garden. They have the largest rosettes of the three genera and usually have just a single rosette or at most a small number. The leathery leaves have short, stiff hairs. Ramonda myconi is native to the Pyrenees, R. nathaliae to Yugoslavia and R. serbica to the Balkan Peninsula. The genus Haberlea has two species; H. rhodopensis and H. fernandi-coburgii. The two are quite similar, having pale blue-violet, campanulate flowers that face outwards (similar to miniature Sinningia). They often grow multi-rosetted and their leaves also have short, stiff hairs. Haberlea bloom about 2 weeks later than Ramonda. The former species is native to central and south Bulgaria and northeast Greece while the latter is restricted to Bulgaria. Jankaea has only one species, J. heldriechii. In the wild, they only grow on Mount Olympus, Greece. They are the daintiest of the group with smaller, silvery-silky haired rosettes. They are usually multiple rosetted and have light silvery-lilac flowers which appear partways between those of Ramonda and Haberlea. These are confirmed lime-lovers and are best grow tucked between limestone rocks or tufa. Some beautiful hybrids exists between Ramonda and Jankaea.
These hardy African violets are not easy to find. Specialty alpine nurseries offer them and periodically you can find them in seed exchanges such as that offered to members of the North American Rock Garden Society. And like African violets, they may also be grown from leaf cuttings. If you are an avid rock gardener or partake of container gardening, then these hardy gesneriads are highly recommended since they are alpines extra ordinaire!
I would like to thank K. Kamstra for the use of the pictures of Jankaea.