Saving Rotted Moon Cactus: Regrafting Best Option

Yellow moon cactus (Gymnocalycium mihanovichii graft) with 1.5" stem left after rot removal: too short for reliable rerooting. Regrafting onto Trichocereus rootstock is better.

Why Rerooting Fails

• Moon cactus lacks chlorophyll (mutant)
• Depends on rootstock for sugars
• Short stem = minimal storage
• Rooting success <20% at this length

Regrafting Protocol

1. Obtain Trichocereus pachanoi or T. peruvianus rootstock (3-4" diameter)
2. Cut rootstock flat; cut moon cactus flat
3. Match vascular rings (center circles)
4. Secure with rubber bands/weight
5. Shade 2 weeks; then acclimate

Attempting Rerooting (If No Rootstock)

• Bury all but 1/2" in dry cactus mix
• No water 2 weeks
• Bright shade
• Monitor for shriveling (failure)

Prevention

• Water rootstock only (not graft)
• Well-draining mix
• Winter: cool, dry, bright

Regrafting is standard for moon cactus. Many nurseries sell rootstock or offer grafting service.