Overwatering
Not a matter of volume but of frequency: roots need air as well as water, and compost that never dries suffocates them. It kills more houseplants than every pest and disease combined, and its cruellest feature is that the early signs — yellowing, wilting, dropping leaves — look exactly like drought, so the instinct is to water more.
What brings it on
Compost kept constantly moist, a pot without drainage or left standing in a full saucer, a pot much larger than the root ball, a cool room in winter where the plant is barely growing, or a heavy soil that does not drain.
source
Sourced guidancehigh confidence
- Royal Horticultural Society: Overwatering — houseplants
Checked 2026-08-13
Preventing it
Ordered by how much difference each measure actually makes, not by how often it is repeated.
- Water by checking the compost rather than by the calendar. Push a finger in to the first or second knuckle and water only if it is dry at that depth — the correct interval varies by a factor of five between a small pot in a bright warm room and a large one in a cool dim room.
source
Sourced guidancehigh confidence
- Royal Horticultural Society: Watering houseplants
Checked 2026-08-13
- Empty the saucer or cachepot after watering. A plant standing in water has no air at the roots at all, and this single habit accounts for a large share of houseplant deaths.
source
Sourced guidancehigh confidence
- Royal Horticultural Society: Watering houseplants
Checked 2026-08-13
- Pot on into a container only slightly larger than the last. A large volume of wet compost around a small root ball stays wet for weeks.
source
Sourced guidancehigh confidence
- Royal Horticultural Society: Potting on
Checked 2026-08-13
Dealing with it once it is there
- Stop watering and let the compost dry out. If the plant does not recover, tip it out and look at the roots: healthy roots are firm and pale, rotting roots are brown, soft and smell sour. Cut the dead roots away, repot into fresh compost in a smaller pot, and water sparingly until new growth appears.
source
Sourced guidancehigh confidence
- Royal Horticultural Society: Overwatering — recovery
Checked 2026-08-13
Signs that lead here
Each of these lists the other things that produce the same sign, and how to tell them apart.
On sprays and treatments
GrowingHQ does not tell anyone what to apply, at what rate, or how often. Pesticide approvals differ by country, change without notice, and the product label is legally binding — it is also the document you are holding. What is described here is cultural and physical control, which is what a home grower can act on without a label in front of them.
Plant-specific guides
Where this is one of several causes that look alike on a particular plant, GrowingHQ publishes the differential rather than the general answer.
- Aglaonema: lower leaves turning yellow
- Ornamental allium: leaves yellowing and flopping after flowering
- Alocasia: lower leaves turning yellow
- Apple: lower leaves turning yellow
- Basil: lower leaves turning yellow
- Bearded iris: leaves yellowing and flopping after flowering
- Calathea: lower leaves turning yellow
- Christmas cactus: plant wilting although the soil is moist
- Christmas cactus: lower leaves turning yellow
- Crocus: leaves yellowing and flopping after flowering
- Echeveria: lower leaves turning yellow
- Jade plant: lower leaves turning yellow
- Lily: leaves yellowing and flopping after flowering
- Moth orchid: lower leaves turning yellow
- Parsley: lower leaves turning yellow
- Peace lily: lower leaves turning yellow
- Pothos: lower leaves turning yellow
- Rosemary: lower leaves turning yellow
- Rubber plant: lower leaves turning yellow
- Sage: lower leaves turning yellow
- Spider plant: lower leaves turning yellow
- ZZ plant: lower leaves turning yellow