Blue Jacob's Ladder
Polemonium caeruleum L.
- light
- Part sun
- water
- —
- tall
- 53 cm
- wide
- 53 cm
Polemoniaceae
Also called Jacob's Ladder
When it flowers
Not known yet in the tropics: too few flowering observations to read a season from.
Read from iNaturalist photographs of it in flower. A month counts at 50% of the best month's flowering share (smoothed over three months) and 10% of its flowering count, from at least 100 flowering observations in the band.
If a child, a pet or anyone may have eaten a plant, contact a doctor or vet straight away, or call the National Poisons Information Centre (AIIMS, New Delhi) on 1800 116 117, free and open 24 hours.
Something wrong with it?About it
- Grows as
- PerennialKew's checklist, not yet checked
- Climate
- TemperateKew's checklist, not yet checked
- Wild in
- Europe to Japan and HimalayaKew's checklist, not yet checked
- Light
- Part shade (3 to 6 h)Read from Wikipedia, checked by a majority of its sourcesBacked by all 6 sources
- Height
- 46 cm to 61 cmRead from Wikipedia, checked by a majority of its sourcesBacked by all 6 sources
- Spread
- 46 cm to 61 cmRead from Wikipedia, checked by a majority of its sourcesBacked by all 6 sources
- Coldest it survives
- -45.6 °C (USDA zone 2a)Read from Wikipedia, checked by a majority of its sourcesBacked by all 6 sources
Not known yet: water, flowers, heat, hottest it survives.
In other languages (12)
- German
- Jakobsleiter, Blaue Himmelsleiter, Blaues Sperrkraut
- root
- POLCAE, …инжбуурал
- Finnish
- lehtosinilatva
- French
- Polémoine bleue, Valériane grecque, Échelle de Jacob
- Czech
- jirnice modrá
- Danish
- Jakobsstige, Almindelig Jakobsstige
- Russian
- Синюха голубая
- Norwegian Bokmål
- fjellflokk
- Dutch
- Jakobsladder
- Lithuanian
- Mėlynasis palemonas
- Estonian
- harilik sinilatv
- Chinese (China)
- 花荵, 电灯花, 穴菜
Where this comes from
- iNaturalist, read 2026-10-25, CC0-1.0 (observation counts)
- Wikidata, read 2026-10-25, CC0-1.0
- Kew's checklist, read 2026-10-24, CC-BY-4.0
- Wikipedia, read 2026-10-26, fact, cited
- Wikimedia Commons, read 2026-10-25, Public domain
- iNaturalist, read 2026-10-25, CC BY
- iNaturalist, read 2026-10-25, CC BY
- iNaturalist, read 2026-10-25, CC BY
- 3D model: Polemonium caeruleum (built for Vanagrha) by Vanagrha, own
A fact “checked by a majority of its sources” was settled by a vote of the pages it was read from, not by a person reading it; one marked “one source” rests on that page alone. Anything else not marked checked has not been checked yet. Where nothing is known, the page says so rather than guess.