Rhipsalis Potting Mixes in Europe
by Luc Scherens, BelgiumAt the Botanical Garden of Heidelberg, I found a mix of coarse pinewood soil with pine cones about 1-inch thick to 1.5 inches long still in it. But the most interesting mix may be one I saw in Bonn.
The primary component of the Bonn mix was wood chips of all kinds. I saw some tropicals like meranti, some beech, softwood and plywood like leftovers from a furniture-making shop that had been passed through a chopper. Some pieces were as long as 2 inches. While I don't know the exact proportions, the mix seemed to be made up of the following:
- wood chips: about 40-50 percent, all sizes and sorts from less than 1/2-inch to more than 2 inches.
- peat: 25 to 30 percent of what looked like a plant soil mix available in Europe composed of brown peat, decomposed leaf mold and fine-grained pinewood soil*.
- lava stone: a few
- coarse sand: not much
- pumice: the white floating porous type known in Europe as "bims" or "bimskies" and in the U.S. as perlite.
- Cow manure pellets: a few
The mix appeared very hard to use because of the wood chips of all sizes. When I grabbed it, I felt the wood splinters sticking all over my hand. I can imagine that it must be very difficult and unpleasant to report a plant with this kind of mix.
I tried the same mix at home, replacing wood chips with ground bark, and I found it to be a well-drained an airy mix. I used bark and mulch instead of chopped wood and came up with the following:
- 5 parts "blond" peat (this is the top layer of the moors, not the deeper more decomposed black peat)
- 2 parts commercial plant soil (based on black peat, leaf mold and some coco peat--well-decomposed)
- 1 part coco peat** to add fibers to the mix
- 1 part coarse builder's or river sand to retain the organic acids
- 1 part "bims" (perlite), about 1/4-inch size, to give some minerals to the mix
- 5 parts extra-ground mulch
- 5 parts fine red pine bark chips about 1/2-inch wide
This mix drains well and doesn't form "mud" when I water from the top. When I squeeze the wet mix it doesn't stay compact. It opens again and remains airy. If you water from below, you may want to add more sand to make the mix heavier so it doesn't float the pots.
For terrestrial types, I use a mix of 3 parts commercial plant soil, 1 part loam, 1 part lava grit and 1 part bims (perlite).
Definitions
*Pine wood soil: Soil from coniferous forest containing partly decomposed
needles, bark and cones like those from pine and other coniferous trees.
**Coco peat: A product that looks like brown peat but made of decomposed coconut fibers. It is a very light brown substance that looks like peat with coconut fibers. Mr. Höller, the head gardener at the University of Bonn, said coco peat is the best medium for rooting cuttings.
