We're pretty good at killing indoor plants, but gradually are building up a small collection of “survivors”… like some sort of abusive cult for rugged plants.
There is very much mildly conflicting information online about succulent soil mixes; the key thing they tend to agree on is there is a large amount of grit and/or perlite (or pumice/etc) in the mix. It is also generally considered the case that they prefer a pH on the slightly acid side (down to 5.5) and thus also prefer watering with rainwater rather than our very hard tap water.
Based on various sources on t'Internet we're going to try potting on any succulents with:
Thus effectively 2:3 organic:inorganic ratio, or 40% organic, 50% inorganic.
I will also mix a “scatter” of a general slow release fertiliser into this.
We will hopefully remember to soak them with an indoor plant feed at least 3 times in a year (Spring, Summer, Autumn)… it may be worth thinking about a special feed for this (more PK, less N?)
And we will endeavour to always use rainwater for these, so long as we have some in the waterbutts (written on a hot dry sunny early May day where we almost cannot remember when it last rained… Norfolk can be a bit of a bloody desert.)
We shelter these over the winder: