How would you propagate cactus pups, like from a barrel cactus?
Cactus pups are best propagated in spring, at the start of the growing season. Wait until they are at least an inch across in diameter. Gently pull (or cut if necessary) the pups away from the mother cactus with a sharp, sterile blade. Let them callous over in a dry location that receives indirect light. This can take days or weeks, depending on how large the cutting is. When the wound is hard and brown, the pup is ready for planting!
Plant in a very fast-draining mix. If there are roots already, great! You can tuck them right into the soil. If not, just nestle the pup on top of the soil, callous-side down. Water so that the soil is uniformly moist. Let it dry out a bit before you water again. Keep the pot in indirect light — the sun is still too harsh for the pups. Roots can take months to form, so you have to have patience. Check every few weeks by gently tugging upwards on the pup. If you feel any resistance, congrats! your plant has rooted. Wait until you see new growth and at that point, you can treat your cactus as an adult.