Does anyone know how to induce a cactus to grow an arm? The cactus I am interested in is a one foot toothpick cactus, (Stetsonia coryne). I think I saw one for sale once, about 18 inches tall, with at least 4 symmetrical arms. The price was $90, and this was 10 or 15 years ago.
This cactus will eventually put on arms naturally, as it matures.
Sorry, but I have zero knowledge of cactus.