
Polemonium caeruleum
Polemonium caeruleum
Safety & Hazards
None known
Cultivation Details
A very easily grown plant, it prefers a moist well-drained fertile soil in sun or semi-shade[1, 2, 3]. Dislikes damp or heavy soils[2], though it tolerates alkaline conditions[4]. Hardy to at least -20°c[5]. A polymorphic species, there are several sub-species[5] and many named forms[4]. Plants are fairly short-lived in cultivation unless they are divided regularly and moved to fresh soil[6]. They can self-sow to the point of nuisance, however[5, 3] and will also survive when growing in lush grass[5]. Cats are strongly attracted by the smell of this plant and will frequently roll on it and injure it[7].
Propagation
Seed - sow spring in a cold frame[8]. Another report says that the seed is best sown in a cold frame in the autumn[9]. When they are large enough to handle, prick the seedlings out into individual pots and plant them out in the summer. Division in early spring or early autumn[2]. Larger divisions can be planted out direct into their permanent positions. We have found that it is better to pot up the smaller divisions and grow them on in light shade in a cold frame until they are well established before planting them out in late spring or early summer. Cite as: Temperate Plants Database, Ken Fern. temperate.theferns.info. 2026-02-21. <temperate.theferns.info/plant/Polemonium+caeruleum>
Pollinators
Bees
References
- [1]RHS Dictionary of Plants plus Supplement. 1956 — F. Chittendon. · Oxford University Press · 1951 · ISBN - ↩︎Comprehensive listing of species and how to grow them. Somewhat outdated, it has been replaced in 1992 by a new dictionary (see [ 200 ]).
- [2]Popular Hardy Perennials. — Sanders. T. W. · Collingridge · 1926 · ISBN - ↩︎A fairly wide range of perennial plants that can be grown in Britain and how to grow them.
- [3]The New RHS Dictionary of Gardening. 1992. — Huxley. A. · MacMillan Press · 1992 · ISBN 0-333-47494-5 ↩︎Excellent and very comprehensive, though it contains a number of silly mistakes. Readable yet also very detailed.
- [4]Encyclopaedia of Herbs and their Uses. — Bown. D. · Dorling Kindersley, London. · 1995 · ISBN 0-7513-020-31 ↩︎A very well presented and informative book on herbs from around the globe. Plenty in it for both the casual reader and the serious student. Just one main quibble is the silly way of having two separate entries for each plant.
- [5]Perennials. Volumes 1 and 2. — Phillips. R. & Rix. M. · Pan Books · 1991 · ISBN 0-330-30936-9 ↩︎Photographs of over 3,000 species and cultivars of ornamental plants together with brief cultivation notes, details of habitat etc.
- [6]Perennial Garden Plants — Thomas. G. S. · J. M. Dent & Sons, London. · 1990 · ISBN 0 460 86048 8 ↩︎A concise guide to a wide range of perennials. Lots of cultivation guides, very little on plant uses.
- [7]A Modern Herbal. — Grieve. · Penguin · 1984 · ISBN 0-14-046-440-9 ↩︎Not so modern (1930's?) but lots of information, mainly temperate plants.
- [8]Complete Guide to Herbs. — Holtom. J. and Hylton. W. · Rodale Press · 1979 · ISBN 0-87857-262-7 ↩︎A good herbal.
- [9]The RHS Gardener's Encyclopedia of Plants and Flowers — Brickell. C. · Dorling Kindersley Publishers Ltd. · 1990 · ISBN 0-86318-386-7 ↩︎Excellent range of photographs, some cultivation details but very little information on plant uses.
- [10]Flora of the British Isles. — Clapham, Tutin and Warburg. · Cambridge University Press · 1962 · ISBN - ↩︎A very comprehensive flora, the standard reference book but it has no pictures.
- [11]A Dictionary of Plants Used by Man. — Usher. G. · Constable · 1974 · ISBN 0094579202 ↩︎Forget the sexist title, this is one of the best books on the subject. Lists a very extensive range of useful plants from around the world with very brief details of the uses. Not for the casual reader.