The Jacob’s-ladder (Polemonium caeruleum) enchants with light blue flowers in June and July. With these tips, the Greek valerian will also grow in your garden.
Profile of Jacob’s-ladder:
Scientific name: Polemonium caeruleum
Plant family: phlox family (Polemoniaceae)
Other names: Greek valerian
Sowing time: autumn
Planting time: April to May, best in autumn
Flowering period: June to July
Location: sunny to partially shaded
Soil quality: sandy to loamy, nutrient rich, humus rich
These information are for temperate climate!
Use in: flowerbeds, bouquets, flower meadow, pond planting, cottage garden, flower garden, natural garden, water garden
Winter hardiness: hardy, USDA Plant Hardiness Zones: 2 (-42 °C / -45 °F)
Bee and insect friendly: Yes
Plant characteristics and classification of Jacob’s-ladder
Plant order, origin and occurrence of Jacob’s-ladder
The Jacob’s-ladder (Polemonium caeruleum) is a perennial that is also known under the name Greek valerian. The early summer bloomer belongs to the genus Jacob’s-ladders (Polemonium), which contains around 30 species and belongs to the phlox family (Polemoniaceae). Polemonium caeruleum is the only Jacob’s-ladder that occurs wild in Central Europe. It thrives above all in moist meadows, floodplains, bank bushes and mountainous regions. In some countries, the species is now considered endangered. The name of the perennial comes from the elongated, pinnate leaves that look like small ladders. On the other hand, reference is made to a passage in the Bible in which Jacob dreams of a ladder to heaven.
Characteristics of Jacob’s-ladder
The Jacob’s-ladder grows upright and is usually between 60 and 80 centimeters (24 and 32 in) high. They are 40 to 50 centimeters (16 to 20 in) wide.
The small, alternately arranged pinnate leaves, from which the perennial owes its name, are characteristic of the Jacob’s-ladder. The green leaves usually consist of 19 to 27 leaflets, sometimes they are even double-pinnate. The regularly structured foliage forms an excellent backdrop for the blue flowers.
The small, sky-blue cup-shaped flowers of Jacob’s-ladder show up from June to July. They are 1 to 2.5 centimeters (0.4 to 1 in) wide and appear in dense, decorative flower panicles on strong stems. Long, conspicuously yellow or orange colored stamens protrude from them. The flowers of the nectar and pollen-rich flower are popular with many insects such as bees, bumblebees and butterflies. Anyone looking for a lovely scented Jacob’s-ladder should choose the scented Jacob’s-ladder (Polemonium caeruleum var. Villosum) with its purple flowers.
After flowering, the Jacob’s-ladder forms capsule fruits that contain elongated seeds.
Jacob’s-ladder – cultivation and care
In the garden, Jacob’s-ladder feels most comfortable in partial shade. With a good water supply, it also thrives in sunny places. In regions with very hot summers, however, shading is essential.
Typical natural locations of the Jacob’s-ladder are nutrient-rich meadows in mountainous regions. In the garden, too, it prefers a nutrient-rich, well-drained and humus-rich soil that is fresh to moist. However, waterlogging should be avoided at all costs.
As a classic wild shrub, the Jacob’s-ladder favors autumn as the best time to plant. Alternatively, put the plant in the ground in April / May. While the nutrient-rich, moist soil is being finely crumbly prepared in the sunny location, soak the still potted root ball in a container with water. It continues as simple as this:
- Dig small pits at a distance of 40 cm (16 in) and mix the excavated material with compost and horn shavings
- Plant the young plant in the middle and dig in to the lower pair of leaves
- Press the earth on with your hands and water generously
A layer of mulch made of leaves or bark mulch contributes significantly to growth and provides winter protection in the first year.
The water requirement of a Jacob’s-ladder is at a high level. Thus, the root ball should never dry out on the inside. If the substrate surface dries, it is watered. During hot summer days, this may well be necessary twice a day. Always water the water directly onto the root disc and avoid sprinkling. A layer of mulch helps to keep the soil wet. If there is bald frost in winter, water the plant on mild days.
A mineral-organic starting fertilization in March / April provides a noticeable boost for this year’s growth. Then pamper the flower every 4 weeks with a portion of compost and horn shavings. A nutritious layer of mulch made from leaf mold or bark humus is also readily accepted by the plant.
Mother nature endowed the Jacob’s-ladder with the potential for a second -bloom. In order for the flower to actually achieve this floral status, a prune is required. After the first bloom has wilted, cut off all the stems down to the basal leaves. Here you only remove leaves that no longer appear healthy and lush. In September and October the plant will delight you with a second bloom. Shortly before the first frost, cut the withered plant close to the ground.
The Jacob’s-ladder can be propagated by division, by cuttings or by sowing.
- The sowing works best if the seeds are harvested shortly before they are fully ripe and sown in boxes with a mixture of sand and humus. The boxes are simply stored in a sheltered place in the garden and kept evenly moist. The seeds usually only germinate in the following spring, as they need a cold stimulus that breaks down the inhibition of germination. The simpler alternative is to simply let the plant seed itself in the bed and dig up the seedlings in the coming year and transplant them to the desired location.
- The division of the rootstock in autumn not only creates more specimens, but also helps to rejuvenate this magnificent perennial.
- For a propagation by cuttings, simply cut off shoots at about 5-10 centimeters (2 to 4 in), place them in a pot with potting compost and keep the soil moist.
The way to the heavenly abundance of flowers is neither rocky nor steep, because the care of a Jacob’s-ladder is limited to the following aspects:
- Never let the soil dry out and water it even in winter when it is freezing
- Fertilize with compost once a month from April to September
- After the first flowering cut back to the basal leaves, this support a second flowering
- Cut back close to the ground in autumn or late winter
Diseases and pests
As for disease, powdery mildew can appear on Jacob’s-ladder. Unfortunately, snails also like the perennial very much.
If the plant has been pruned in autumn, no further precautions need to be taken in the bed for overwintering. The flower is so frost-resistant that it doesn’t even mind temperatures of – -42 °C / -45 °F.
Plants in the pot, however, there is a risk that the root ball will freeze. Wrap the vessel in bubble wrap or winter fleece and place it on a styrofoam plate or a block of wood. Small buckets with a diameter of less than 30 cm (12 in) should ideally be placed in frost-free winter quarters.
Use in the garden
Jacob’s-ladder is ideal for perennial beds and looks very nice next to iris and lady’s mantle (alchemilla). In addition to columbine, meadowsweet, primrose species and day lily, it also sets beautiful accents in the natural garden on meadow-like open spaces. At the foot of the Jacob’s-ladder, it is advisable to plant low neighbors such as field chamomile so that the blue beauty does not look too bare at the bottom. With its nostalgic charm, Jacob’s-ladder fits particularly well into the cottage garden, but can also be placed on the edge of the pond. The low scented Jacob’s-ladder (Polemonium caeruleum var. Villosum) is particularly recommended for the foreground of the bed. If you want, you can also use the Jacob’s-ladder as a cut flower.
An enchanting variety of Polemonium caeruleum is ‘Album’, which is 30 to 50 centimeters (12 to 20 in) high and beguiles with white peel flowers.
A specialty are colorful Jacob’s-ladder varieties. The variety Polemonium caeruleum ‘Brise d’Anjou’ is quite common. Each leaf of this Jacob’s-ladder enchants with a creamy yellow, almost white margin. If you remove the rather unspectacular flowers, you can even encourage the decorative foliage to sprout.
Another interesting variety is the pink Jacob’s-ladder ‘Lambrook Mauve’, which was cultivated in England. It is characterized by abundant delicate lilac flowering, is true to location and a recommended addition to the spring bed. The variety grows up to 50 centimeters (20 in) tall and tolerates both sun and partial shade if the soil is sufficiently moist.