Do I use lapillus or just pumice? Is peat really a cactus-killing devil, as we hear people say? But then why nurserymen cultivate their plants nearly 100% with peat, and their plants don’t die in the greenhouse? The question about materials and elements that end up in compost for cacti and succulents is a limitless one. Firstly because the variables are endless and range from growing regimes, environmental factors, latitude, to plant type (for example, there are differences in substrate requirements between a caudiciform and a cactus). Then, because the same elements, as like the field soil, can vary immensely between them – for example, based on the area where it is picked up: it’s evident that the loam of the Po Valley, where I live, cannot have the same chemical characteristics as that one existing in Bolivia, for example.
So, how can we orient among the many elements and materials we can find – some easily, others less – to mix them and make good compost? A first answer, perhaps obvious but reasonable, is to do experience and direct observation. In a word: experimentation. Another one, trivial but overlooked, is knowledge – the knowledge of the single “ingredients” properties that create the substrate and of the individual plant’s needs.