Root Rot, Caught Early Enough to Matter

Root rot kills more houseplants than every pest combined, and it does it while looking like the opposite problem.

Why it looks like drought

Rotted roots cannot take up water. The plant wilts, the leaves yellow and drop, and everything above ground says the plant is thirsty.

The owner waters it. The soil is already saturated, the remaining roots suffocate, and the decline accelerates. That feedback loop is the whole story, and it is why the single most useful diagnostic habit is checking the pot before reaching for the watering can — the point made in overwatering or underwatering.

The check

Tip the plant out. It is less disruptive than it sounds and takes two minutes.

Support the stem between two fingers, invert the pot, and tap the rim against something solid. The root ball usually slides out intact. If it does not, run a knife around the inside edge first.

The sliding-sheath test is the reliable one. Pinch a root and pull gently: a healthy root resists, a rotted one strips its outer layer off and leaves a thread of central tissue behind.

Smell

Healthy potting mix smells of earth. Rotting roots smell sour or of drains, and the smell is detectable at the drainage holes before anything is visible above ground.

It is worth checking a struggling plant this way first, because it costs nothing and is often conclusive.

What causes it

Water sitting where roots cannot get air. Every cause reduces to that.

No drainage hole. Decorative pots without one hold a reservoir at the bottom that never leaves. The commonest single cause.

A saucer left full. Same problem, one layer up.

A pot far too large. Soil the roots have not reached stays wet for weeks.

A dense mix. Standard potting compost holds too much water for succulents, cacti and most aroids.

Cold. A plant in a cold room uses far less water, so the same watering schedule that worked in summer drowns it in winter.

Note what is absent from that list: watering too often, on its own, is survivable if the water can leave. Drainage is the variable that matters.

Treating it

Remove the plant and wash the soil off the roots under a tap.

Cut away everything soft, back to firm tissue, with clean scissors. Be less conservative than feels comfortable — a root that is soft anywhere is dead along its length.

Repot into fresh mix, dry rather than pre-moistened, in a pot only slightly larger than the remaining root ball. A plant that has lost half its roots cannot support a large volume of wet soil.

Cut back some top growth to match. A reduced root system cannot supply a full canopy, and the leaves will drop anyway.

Then water sparingly and wait. New growth is the signal it has taken; nothing else is.

When to give up

If no firm root remains, it will not recover, and continuing to nurse it wastes weeks.

Most affected houseplants root readily from cuttings, and a healthy cutting taken from the top of a dying plant is a far better prospect than the plant itself. That decision is easier made early, while there is still undamaged growth to take.

Preventing the repeat

Drainage holes in everything. Saucers emptied half an hour after watering. Pot sizes increased one step at a time. A gritty mix for anything that evolved somewhere dry.

And water by checking rather than by schedule — a finger two inches into the soil answers the question a calendar cannot.