Potting soil for Soldanella and Viola biflora

[JPB]

I'm about to repot S. alpina and V. biflora. Do they need an "alpine" compost or do I grow them in normal soil? What would be the optimum pH of the soil?
Thanks, HAns

[Lesley Cox]

Hans, there are many people on the Forum who can give you better advice than I, but in general, I'd suggest you pot ALL alpines with a reasonably open compost, including some leafmould or other organic matter and some grit which assists with drainage and also is friendly to the roots of alpine plants. Soil on its own cloggs up a pot and makes it difficult for it to drain well and also can become very compacted and hard, inimical to alpine root systems.

Having said that, I now use a small percentage perhaps 10% of loam in my potting mix as I find plants are less susceptible to fungus diseases than in purely soil-less composts.

[Heather Smith]

Hans, I would agree with Lesley that leafmould would be useful for the Soldanellas but add a great deal of grit to ensure very good drainage. It grows above the tree line and the flowers come up just after the snow melts (sometimes flowering through the snow)  It likes a lot of water during the growing season but excellent drainage to prevent water lying around the roots. One word of warning though - they are very tasty to slugs/snails and need protection especially during the winter and spring when the flowerbuds can be eaten off before they can even get above the leaves.

Viola biflora grows everywhere including the wooded slopes where it can get some light, but needs perfect drainage - it grows in rock, in cracks and crevices and under overhangs of rock. Lots of grit is necessary, maybe 50% or 60%. No special pH conditions as far as I know. If you have seen them in the Alps, you will know the conditions they like best.

I grow Soldanellas but not the Viola as yet. They flower either fairly well or very well from year to year.

[mark smyth]

my Soldanellas grow in my peat bed in half shade and flower profusely

[johanneshoeller]

Soldanella alpina and Viola biflora grow near my house in the Upper Austrian Calceolus Alps.
I can say you that these plants are very difficult to grow in our gardens for a long time.
To grow them from seed is easy, no special requirements to the soil. I use acid soil (peat, TKS 1)with grit.
After some years the plants die. But the seed has germinated in my garden between Alpine Primulas and shows many flowers. And so I mean that the natural soil for Alpine Primulas (minima, auricula, clusiana, marginata,...) would be the best. To grow them in pots is very difficult, specially Viola biflora is neary impossible to grow. In my country you can find them full in sun at an altitude of 1500m and higher and only a few in lower locations. You will very often find Soldanella alpina in common with grass.
There are no problems with Soldanella montana, this one is very easy to grow!
Enclosed some photos of my garden plants.

Hans
from Austria

[JPB]

I finally potted them up. pH was around 6 in the old compost which seems fine, so I didn''t chage that. I put grit in the lower half of the pots and added grit and oak-leafmold to the new compost. It is much more open now for both species. I'll let you know if/once they flower next spring.
Thanks for your advice!
Hans

[Olga Bondareva]

Hans, you are absolutely right with the compost. I grow S. montana and S. alpina in pots using mixture of peat, coarse-grained sand and leaf humus 1:1:1. It is slightly acidic. My "normal" loamy soil is too heavy. One year seedlings flower well in peat mixture.