Hydrophobic compost
Compost that has dried so thoroughly it will no longer absorb water: the water runs down the gap between the root ball and the pot and out of the base, so the pot feels watered and the roots stay dry. It is common in peat-free mixes and produces a plant that wilts however often it is watered.
What brings it on
A pot allowed to dry out completely, particularly a peat-free or bark-based compost, and most often after a period away from home.
source
Sourced guidancemoderate confidence
- Royal Horticultural Society: Watering containers
Checked 2026-08-13
Preventing it
Ordered by how much difference each measure actually makes, not by how often it is repeated.
- Do not let container compost dry out completely. Where a plant is left for a while, standing it in a shaded position reduces how fast it dries.
source
Sourced guidancemoderate confidence
- Royal Horticultural Society: Watering containers
Checked 2026-08-13
Dealing with it once it is there
- Stand the whole pot in a bowl of water for half an hour or more, until the compost is wet through, then let it drain. Watering from the top will not rewet it once it has reached this state.
source
Sourced guidancehigh confidence
- Royal Horticultural Society: Watering containers
Checked 2026-08-13
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.