Root rot triage: the 48-hour window and the surgery after it
Rot is a timing problem. Caught in the first two days it is a repot; caught in the second week it is a behead; caught in the third week it is compost. The entire skill is recognising the early signs, which are not the ones most guides list.
The early signs, in the order they appear
Day 1–2: the substrate stays dark for two days longer than usual, and the pot is unexpectedly heavy. No leaf symptoms yet.
Day 3–5: the lowest one or two leaves become soft while the rest of the rosette is firm, and they detach with a wet, translucent base rather than a dry scar. The stem at the soil line feels slightly cool to the back of the hand.
Day 6–10: the stem darkens from the soil line upward and gives slightly under thumb pressure. Leaves lose turgor across the whole rosette even though the mix is wet. At this point the rot has passed the crown and a repot will not save the plant — only a behead above the infection will.
Surgery, step by step
Unpot and wash the roots under running water at room temperature so you can see colour. Healthy roots are pale tan and firm; rotted roots are brown-black and slip off the core leaving a thread. Cut back with sterilised scissors until every remaining root is pale inside.
Then cut the stem in 5 mm slices from the base upward until the cut surface is clean, pale and shows no dark ring. Every slice must be clean; if you stop at the first clean-looking cut you will usually leave infected tissue behind. Dust the cut with sulphur or cinnamon and leave it in open air, out of direct sun, for seven to ten days.
Restarting in dry mix
Set the callused plant on dry mineral mix, not in it — the cut base should touch the surface without being buried. Keep it at 22–24 °C in bright indirect light. Do not water for ten days; then water at the rim very lightly, about 30 ml for a 12 cm pot, and repeat every seven days.
Roots from a beheaded rosette at 22 °C appear in 20–35 days, which is slower than a normal cutting because the plant has to rebuild its reserves. The first sign of success is not roots but a slight firmness returning to the centre leaves.
What caused it, in order of likelihood
First: a substrate that stays wet below the root zone, usually from a mix with too many fines or a pot too deep for the root mass. Second: watering on a surface reading rather than a weight or turgor reading, which in a cool room means the plant is watered while the lower profile is still saturated.
Third, and least often blamed: a saucer left full. A pot standing in 1 cm of water at 20 °C draws water back up by capillary action and keeps the base of the profile saturated indefinitely, and it does so silently — the surface looks correctly dry the whole time.
| Month | State | What the plant wants |
|---|---|---|
| January | Growth | Deepest rest. Water only if the lowest leaf ring softens; keep the room as bright as you can. |
| February | Growth | Late rest. Daylight is returning — begin adding an hour of supplementary light every two weeks. |
| March | Growth | Repotting window opens for summer growers. Trim roots, refresh the mineral fraction, dry for a week. |
| April | Growth | Growth restarts. First full watering at the rim, then resume the published interval. |
| May | Growth | Peak growth and the offset season. Feed at quarter strength every third watering. |
| June | Growth | Lengthening days, rising heat. Watch the leaf turgor test rather than the calendar. |
| July | Growth | Hottest weeks. Water in the evening, a third of the spring volume, and only on a visible symptom. |
| August | Growth | Heat eases at night. Prepare mix and pots for the autumn repotting window. |
| September | Growth | Autumn window for winter growers. Root-prune and repot while the soil is still warm. |
| October | Growth | Peak autumn growth. This is the season when most colour work should be done. |
| November | Growth | Daylight falls fast. Taper watering by a quarter and stop feeding entirely. |
| December | Growth | Slow, dry and bright. This is the colour peak for most genera in the collection. |
Tinted rows are the months this genus is genuinely out of action: no repotting, no feeding, and water only if the plant visibly shrinks.
Four things to take away
- The first tell is a pot that stays heavy, not a leaf that changes colour.
- Slice the stem until the cut face is clean all the way across — every slice.
- Rest the callused plant on dry mix, not in it; roots in 20–35 days.
- The usual cause is fines in the mix, a too-deep pot, or a saucer left full.
Informational only — This page is a cultivation record, not horticultural or plant-pathology advice. Any treatment should follow the product label and local regulation.