[header] How to grow cactus indoors [title] Take a cutting from a healthy cactus. [step] You can grow new cacti from a pup that shoots off of a healthy mother plant. Choose a pup that's plump, unblemished, and healthy. 
Gently cut or break off an entire pup from the plant. [substeps] You can also buy cacti at local nurseries, home stores, and garden centers.