Root Rot on zz plant
What's Happening
ZZ Plant (Zamioculcas zamiifolia) develops basal petiole rot primarily from Phytophthora nicotianae infection, which thrives in waterlogged, anaerobic soil conditions. The plant's succulent rhizomes store water extensively, making them highly susceptible to rot when soil remains saturated for 7+ days. Unlike true root rot in other species, ZZ rot begins at the rhizome crown and progresses downward, often showing black discoloration with white mycelial overlay indicating active pathogen colonization. CAM photosynthesis enables drought tolerance but creates vulnerability when roots are suffocated.
How to Fix It
- 1
Unpot immediately and inspect rhizomes—healthy tissue feels firm like a potato; rotting tissue yields to gentle pressure and appears black with possible white fungal overlay
- 2
Trim ALL blackened, mushy tissue with sterilized blade, cutting 1cm below visible infection line
- 3
Seal fresh cut immediately with super glue, wax, or cinnamon powder to prevent reinfection—ZZ rhizomes exhibit poor natural callousing
- 4
Treat remaining healthy tissue with 3% hydrogen peroxide dip (1:1 with water) for 10 minutes to sterilize
- 5
Repot in completely dry, gritty mix (50% perlite/pumice, 30% potting soil, 20% coarse sand) with drainage holes
- 6
Withhold water for 2-3 weeks post-treatment; maintain 50-60% humidity and 65-75°F
- 7
Monitor weekly; new white root tips typically emerge in 4-8 weeks
How to Prevent It
Adopt 'neglectful' watering schedule—allow soil to dry completely (top 2-3 inches bone-dry, typically 3-4 weeks between waterings). Use terracotta pots with drainage holes. Check soil moisture with wooden skewer or finger test before watering. CAM photosynthesis means ZZ plants metabolize water slowly; overwatering frequency, not volume, causes rot.
Related Problems
Same Problem on Other Plants
Go Deeper
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