llms.txt · Watering plan · Knowledge
Why containers need more watering than beds
Pots hold little water and often sit in a rain shadow. The Johgee core credits only a quarter of reported rain for containers.
Generated 2026-08-23T10:00:00.000Z. Valid until 2027-02-23T10:00:00.000Z. Ruleset facts below must match the Johgee core.
Locked facts
- Container landscape coefficient is 0.9.
- Container rain effectiveness is 0.25; in-ground rain effectiveness is 0.8.
- 1 mm over 1 m² equals 1 litre
A border can bank rain in the soil. A pot cannot. Compost dries from every side, and many containers sit under eaves, benches or foliage, so a shower that wets the lawn may miss the pot entirely.
For that reason Johgee credits only 0.25 of recent and forecast rain for containers, against 0.8 for ground-planted beds. Container demand also uses a higher landscape coefficient (0.9). The calculator still needs the number of containers, not a guess at hidden soil volume.
RHS guidance is to check pots with a finger or by weight, and to water until it just leaves the drainage holes. Do not assume tonight's forecast will water the compost for you.
Sources
This is a decision aid, not a guarantee.