Two-tone plants are made with a knife too
The bright red or yellow moon cactus sold in garden centres cannot survive on its own roots: it is a colour mutant of a South American cactus with almost no chlorophyll. Growers keep it alive by grafting it onto a green cactus that feeds it, which gives the plant its two-tone look. A clean, flat cut from a grafting knife is how the two halves are joined.
