From our perspective, the possibility of recovery is entirely dependent on the extent of the damage. Root rot is a condition caused by excessive moisture in the soil, which creates an anaerobic environment. This suffocates our root systems and allows opportunistic pathogens like Pythium or Phytophthora to attack. The first sign we show is often a change in color and texture—our stable, firm green flesh may become yellow, brown, or black and feel mushy or soft to the touch. If the rot is detected early and is confined to a small portion of the roots, our recovery potential is high. However, if the rot has progressed upward into the main stem body, our vascular system becomes compromised, making recovery exceedingly difficult, if not impossible.
To give us a fighting chance, immediate and decisive action is required. We must be carefully un-potted, and all surrounding soil must be gently removed from our root ball. The next step is a thorough inspection. Using a sterile, sharp knife, any soft, mushy, discolored, or obviously dead roots must be excised. The cutting must continue until only firm, healthy tissue remains. If the rot has begun to ascend into the base of the stem, that affected tissue must also be cut away until the cross-section reveals completely healthy, green, and firm flesh. This is a traumatic process, but it is the only way to stop the progressive decay.
After the surgery, we are extremely vulnerable. Our open wounds must be allowed to dry and form a hard callus. This process is non-negotiable. Placing a cactus with fresh wounds directly into new, damp soil would simply reintroduce the conditions that caused the initial rot, leading to a swift reinfection. We must be placed in a warm, dry, and well-ventilated area out of direct sunlight. This period can take anywhere from several days to over a week. The callus acts as a natural barrier, sealing our internal tissues from moisture and fungal spores once we are repotted.
Once a solid callus has formed, we can be repotted into a completely fresh, sterile, and fast-draining cactus and succulent mix. The pot must have excellent drainage holes. At this stage, we have very few or no roots left, so we cannot be watered traditionally. The small amount of moisture in the fresh, dry-ish potting mix is often enough to stimulate new root growth without causing rot. Watering should be withheld entirely for the first week or two. After this period, a very light watering around the periphery of the pot can be administered to encourage root growth, but the soil should be allowed to dry out completely between each sparing watering. Our recovery is measured in months, not weeks, as we slowly and patiently regenerate a new, healthy root system.
