The name Jacobs Ladder is given to the plant Polemonium because the arrangement of the leaves – successive pairs of opposite leaves resembling a ladder. And, any ladder has to refer to”Jacob’s” given that those naming plants tend to use classical references.
There are two theories on the origin of the name Polemonium. The first is that it derived from the Greek word – polemos which means ‘war’. The reference says that how this was transferred to the plant is somewhat vague. The second source claims that the plant was originally named after the herbalist and healer Polemon of Cappadocia. Similarly, the second source suggests that there is no guarantee that the plant we now know as Polemonium is the original one that earned the name.
Where to Grow
However we name it, Jacobs ladder thrives in part shade situations. Give it too much sun (particularly the variegated cultivars) and it will melt away. It grows 18 to 36 inches in height and mostly blossoms in shades of blue (there is also a white flowering variety).
Hardiness rating would put it easily into USDA zone 4 and possibly 3.
Bloom Time and Spacing
Jacobs ladder is a good plant for the early summer flowering garden, they should be spaced 12-18 inches apart.
Given the choice, it grows best in a moderately fertile soil. The higher the organic matter, the better and it must be well-drained. Standing water or clay soils will shorten its life quickly.
Jacobs ladder is propagated by division (easy in the early spring) or seed (again easy). The named varieties are best divided as they don’t come true from seed.
- P. reptans is a short 12 inch tall species that, if left unchecked, can become quite weedy in the garden. I happen to like its mid-blue flowers and even though it is a bit of a weed, I leave it to fill in spaces through the garden. I likely weed more plants than I leave but I do enjoy this short Jacobs ladder.
- ‘Blue Pearl’ is a light blue form and quite short. I killed this one by giving it too much sunlight in a dry year. It did not reappear the following spring.
- ‘White Pearl’ is a dwarf white form. Not overly impressive in my opinion but it is available at garden centers.
- ‘Pink Beauty’is 12 to 18 inches tall with rose flowers
- ‘Lambrook Mauve’grows 12 to 18 inches, lilac flowers on reddish stems. Good bloomer.
- ‘Stairway to Heaven’ is one of the best variegated plants and one of my favourite spring bloomers.
- P. caeruleum subspecies amygdalinum
- ‘Brise d’Anjou’. This Jacobs ladder has taken the gardening world by storm. The fern-like leaves are edged in yellow and gives the plant season long appeal from the foliage all by itself. The flowers are a mid-blue. This variety has been very popular but tends to die quickly when the weather turns too hot.
- ‘Snow and Sapphire’is a variant of ‘Brise d’Anjou’ that is supposed to be more weather tolerant. While ‘Brise d’Anjou’ “melts out” in high summer heat and dies, ‘Snow and Sapphire’ takes more punishment. I’ve grown both and had more success with ‘Snow and Sapphire’.
- P. caeruleum subspecies himalayanum. This is a slightly taller form of Polemonium and worth growing for the deep blue flowers. It is often sold as P. himalayanum in seed catalogs. I like this plant more than almost any other.
Cats and Concerns
While not as badly damaged by cats as catnip, this plant is also a favorite of felines and will, if bruised or cut to release a fragrance, shortly be visited by cats for a good roll. It is good for the cat but not so good for the plant.
The plant was used by herbalists as a cough remedy.
There are no indications that the plant is poisonous.