Bulb food
Ina Crossley (Sat, 24 Oct 2015 15:29:30 PDT)

Thank you Rodger. That is most interesting. Where I live the soil is
volcanic and plants love it. I didn't connect the fact of that with the
pumice I now use in containers. I have done no horticultural training,
just a gardener from a young age. And get a feel of what agrees with
them and what doesn't. Great to know your info on this.

Ina Crossley

On 22/10/2015 8:42 a.m., Rodger Whitlock wrote:

On 21 Oct 2015, at 16:01, Hans Huizing wrote:

I also use Pumice.
For the more difficult Cyrtanthus species I use pure Pumice 2-5 mm.
The root system develops very well in this material.

A demonstration that plant roots need air too. And I don't mean just epiphytes.

Since this material contains no nutrients...

Pumice (volcanic pumice) is nutrient-rich like other volcanic ejecta. Think
about the slopes of Mt. Vesuvius, which have been farmed for millenia because
the soil (decomposed ejecta) is so rich. Particularly rich in potassium, I
understand. The best part is that the nutrients in pumice are released slowly.