A soft or mushy base to the stem
The one to act on today. Soft tissue at soil level means rot has reached the crown, and the plant is lost from the bottom up unless it is taken apart now.
This one is worth acting on today rather than at the weekend. A week of waiting changes what is left to save.
What it usually is
1 Root rot from compost that never dries
| How to tell | Press the stem gently just above the compost. Healthy tissue is firm; rot gives under a finger and may weep. Tip the plant out: sound roots are pale and springy, rotten ones are brown or black, smell sour and slide off leaving a bare thread. |
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| The fix | Take it out of the pot today. Wash the roots clean, cut away every soft root and any soft stem back to firm white tissue, and repot into fresh, gritty, barely moist compost in a pot with a drainage hole. Do not water for a week. Do not feed. Throw the old compost away. |
2 Water sitting in the crown
| How to tell | Rot beginning at the point where the leaves meet the stem rather than at the roots, on a rosette plant like an echeveria, an African violet or a bromeliad that has been watered from above. |
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| The fix | Water at the compost rather than over the plant, and never leave water sitting in a rosette overnight in a cool room. Remove the affected leaves and let the crown dry. If the growing point itself is soft, take a healthy leaf or offset and start again. |
3 A pot with no drainage, or a saucer left full
| How to tell | A decorative pot with no hole, or a saucer that has held water since the last watering. The bottom third of the compost will be sodden and may smell. |
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| The fix | Move the plant into a pot that drains, or use the decorative pot as a cover with the nursery pot inside it and lift the inner pot out to water. Empty every saucer twenty minutes after watering, every time. |
Through the year. Most rot begins in autumn and winter, when the plant uses a fraction of the water it used in summer but the watering habit has not changed. A cold room makes it faster, because cool wet compost holds less air still.
This is the one symptom in the journal marked urgent, and the reason is simple: by the time the base of the stem is soft, the roots have been dying for weeks and the plant has days rather than months. Everything else here can wait for the weekend. This cannot.
What is happening is not really a disease of the plant, it is a suffocation. Roots respire, which means they need air in the spaces between the particles of compost. Compost that stays saturated has no air in it, the fine feeding roots die, and the organisms that live in wet soil, pythium and phytophthora among them, move into the dead tissue and then into the living. The soft base is the last stage of that, not the first. The pot and the mix are the first things to get right, and choosing a pot covers both.
So the treatment is surgical rather than chemical. Tip the plant out and look. Healthy roots are firm, pale and springy and smell of nothing much. Rotten roots are brown or black, slide out of their outer skin when pulled, and smell sour and stagnant. Cut everything soft away with clean scissors, going back into firm tissue, and do the same to the stem: if the base is soft but there is firm stem above it, you may be able to cut above the rot and root the top as a cutting.
Then repot into fresh compost with grit or perlite through it, in a pot that drains, and keep it barely moist for a fortnight. Do not feed a plant that has just lost its roots; it has nothing to feed with. Do not put it into a bigger pot, which gives it more wet compost to sit in. And do not water on a schedule afterwards. Water when the top third of the compost is dry, which for a plant with reduced roots will be much less often than before.
Some plants will not come back. A succulent or a cactus that has gone soft at the base is usually finished, and the only thing to save is a cutting from above the damage. Take it, let the cut dry for a few days until it seals, and stand it on dry compost.
Entries that name it
What the journal says about this symptom on each plant.
| African violet | Crown rot from water sitting in the middle of the rosette or compost kept too wet. Remove affected leaves, let the compost dry more between waterings, and always water from below. |
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| Aloe vera | Root and stem rot from compost that stays wet, usually in winter. Tip it out, cut back to firm white tissue, let the cut dry for two days and repot into dry gritty mix. Do not water for a week. |
| Christmas cactus | Stem rot from wet compost, usually in winter. Take healthy segments as cuttings, let them dry for a day, and start again in fresh gritty mix. |
| Dragon tree | Root rot from a large pot that never dries. Unpot, cut away every soft root, repot into a smaller pot of fresh compost and water sparingly until it grows again. |
| Dumb cane | Stem rot from cold wet compost. Cut above the damage into firm tissue, root the healthy top, and discard the base. |
| Echeveria | Rot from wet compost or from water sitting in the rosette. Cut away everything soft, let the healthy top callus for a few days, and re-root it in dry gritty mix. Water into the compost from now on. |
| Golden dewdrop | Root rot from poorly drained soil or overwatering, the most common way an otherwise easy shrub is lost. Improve drainage before replanting, and let the top of the soil dry between waterings rather than keeping it constantly damp. |
| Jade plant | Stem rot from wet compost, usually over winter. Cut above the damage into firm tissue, let the cutting callus for a week, and start again in dry gritty mix. The old root ball is not worth saving. |
| Lavender | Wet winter roots in heavy ground or a pot that does not drain. Plant on a slope, in a raised bed, or in gritty compost, and never mulch a lavender with anything that holds water against its stems. |
| Lucky bamboo | Stem rot from stale water or a stem cut that never sealed. Cut the stem back into firm green tissue, rinse the vessel, and start again with fresh water. Rot travels up a stem and cannot be reversed. |
| Rosemary | Wet roots over winter, in heavy ground or a pot with a saucer under it. Plant on a mound or in a raised bed with grit in the hole, mulch with gravel rather than bark, and take the saucer away. |
| Snake plant | Overwatering, especially in cold conditions. Stop watering, unpot, remove rotted sections and repot in dry gritty mix. |
| String of pearls | Rot at the crown from compost that stayed wet. Cut away every soft strand, take healthy cuttings from the rest, and start again in dry gritty mix in a shallow pot. |
| Yucca | Cane rot from compost that stays wet, most often over winter. Cut the cane back above the damage into firm tissue, let the cut dry, and re-root the healthy top. The rotted base cannot be saved. |
| ZZ plant | Rhizome rot from long term wet compost. Unpot, cut every soft brown rhizome back to firm white tissue, let the cuts dry for a day and repot into fresh gritty mix. Water sparingly until new stems appear. |
Questions from the margin
- What does it mean when the base of the stem goes soft?
- Root rot has reached the crown. The roots have been dying for weeks in compost that never dries, and the soft base is the last stage rather than the first. It needs acting on the same day.
- Can a plant recover from root rot?
- Sometimes, if there is firm tissue left. Wash the roots clean, cut every soft root and any soft stem back to firm pale tissue, repot into fresh gritty compost in a pot that drains, and do not water for a week. If the whole base is soft, take a cutting from the firm top instead.
Checked against RHS, Root and foot rots; Penn State Extension, Root rot of houseplants.