Polemonium

Botanical/Latin
   Polemonium

Pronunciation
   pole-mone-e-um

Common Name
   Jacob's Ladder

Hardiness zone range
   3 - 7

General Comments
These charming, old fashioned style perennials have delicate, soft green, fern-like foliage and clusters of blue (sometimes white and pink), bell shaped flowers in late spring and early summer.

Uses
They are a refreshing sight in shady, woodland settings where the cool blue shades are accentuated by the softer light conditions. Their old fashioned appeal fits perfectly in cottage gardens and in perennial beds and borders, while the soft, green, ferny foliage (which is attractive even when they are not in flower) blends harmoniously with wild flowers in meadows and natural style layouts.

Light Preference
Best in shade to partial shade, where the cooler, shady conditions promote better growth and a longer flowering period.

Culture
Easy to grow and troubled by few pest or diseases, they thrive best in rich fertile soils that are well drained and remain cool and moist during the growing season. They do not like to become dried out, so it is a good idea to supplement the planting area with moisture retaining organic matter (peat, compost, leaf mold, etc.) and then applying a heavy mulch after planting.

They require little maintenance, except perhaps a light dressing with a well balanced fertilizer in early spring, watering during dry spells and an occasional clean up to remove old leaves and flower stems.

They benefit from regular division; this helps to keep the cultivated varieties healthy, vigorous, and longer lived. The best time to do this is in early spring (although it can also be done in fall). Clumps are lifted and healthy vigorous pieces split apart and then replanted amending the soil as above.

Background
There are about 20-25 species of Polemonium and most are native to Europe and western North America. The most commonly cultivated species is P. caeruleum. It is a European species and has been cultivated since Roman times. The lavender-blue flowers have remained a firm favorite over the centuries.

The origin of the botanical name is somewhat obscure. It is thought to be from the Greek word polemos meaning war. Since the leaves resemble the ancient ladders that warriors used to attack fortifications, there is credibility to that theory. The plants became commonly known as ladder plants. This then became colloquially linked to the biblical story of "Jacob's ladder".

Another explanation dates back to the Roman writer, Pliny, when he recorded that two Kings fought and went to war over the discovery of this plant. Each claimed that he had found it first. One of the kings was King Polemon of Pontus. It is not known if he was victorious and if the plant was named after him, but it is interesting to note the level of esteem that these plants apparently commanded.

Splendor Suggestions
Polemonium caeruleum, once established, has a tendency to self seed and produce new seedlings with ease. In a natural setting, this can be a desirable characteristic with drifts of these popping up in naturalized areas and woodland. On the other hand, in a garden setting the seedlings can be too plentiful for some gardeners liking. In a situation like this, it is important to "deadhead" them as they finish flowering. This removes the old flower heads and prevents the production of seeds.

Companion Plants
They combine well with bold foliage plants, so Hostas make wonderful partners; we like them with the big blue leaves of Hosta sieboldiana `Elegans' or `Blue Angel' or the muted chartreuse of `Sum & Substance'. Feathery textured plants like Aruncus dioicus (Goatsbeard) and Astilbes provide a light and airy look, while ferns blend so well with the foliage and help to continue the show well after they have finished flowering.

When it comes to ground cover, Persicaria `Dimity', with its pink spikes and spreading foliage, is a good option, while the golden yellow flowers of Chrysogonum virginianum contrast with the blue flowers. Lamium `White Nancy', Viola `Maggie Mott', and Veronica `Goodness Grows' are other good possibilities.