I believe that anyone interested in cultivating this fascinating species should read this report, first:
Below are two quotes taken from this report:
"Soil on the south coast of Spain is sandy or loamy, slightly acid to neutral, lime-less and poor in nutrients. The geologic underlay consists of sandstone. Drosophyllum also grows directly in sandstone crevices."
"During our observations in its native habitat, we have never seen Drosophyllum growing in alkaline soils, despite several intensive searches at suitable places."
It appears that the belief that Drosophyllum, in situ, grows in alkaline (high pH) soils, is mistaken.