Jacob's ladder Polemonium caeruleum 15-20 pot P9

Size: Potmaat leidend

15-20cm

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Pot 9x9 cm (P9)

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Available from: 03/02/2025

Number of m2

Nr. of plants

2.90

2.90 per piece

incl. VAT, excl. shipping costs (calculated in shopping cart)

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2+ £3.20

6+ -1.6% £3.15

12+ -4.7% £3.05

24+ -6.3% £3.00

96+ -9.4% £2.90

Benefits according to our specialist

Plantable year-round
Low maintenance
Easy plant

Plant features
Description
Planting and care
Packaging and shipping

Genus
Polemonium (view all varieties)

Root type
Pot

Pot size
9x9 cm (P9)

Flowering months
May, June, July

Leaf colour
Blue

Possibilities
Border, Group planting

Soil type
All soil types, well-drained

Positioning
Semi-shade, Sun

Winter hardiness
-23,3°C / -20,6°C, USDA zone 6a

Fruit-bearing plants
No

Water needs
Average water

Number of plants per m²
9

Evergreen plants
No

Leaf colour
Green

Fragrant plants
No

Growth habit
Upright growth habit

Height at time of delivery excluding pot/clod
15-20

Mature height (cm)
60

Art. no.
1000958

Description

Polemonium caeruleum | Jacob's ladder

The charming Polemonium caeruleum, commonly known as Jacob's ladder or American great valerian, is a delightful perennial that brings a touch of woodland enchantment to any garden setting. Admired for its distinctive foliage and beautiful blue flowers, this species is a favorite among gardeners looking to create a serene and visually appealing border or group planting.

With its origins in the northern temperate zones of Europe, Asia, and North America, Polemonium caeruleum thrives in a variety of well-drained soils and is suited for sunny to partially shaded locations.

Key Features

The Polemonium boasts an array of key features that make it a must-have for plant enthusiasts:

It exhibits an upright growth habit, reaching an ultimate height of approximately 60 cm.
The lush green foliage provides a perfect backdrop for the striking blue flowers that bloom profusely from May through July.
While not evergreen, the deciduous nature of the American great valerian allows for a fresh burst of green each spring.
This species does not bear fruit but instead focuses its energy on producing an abundance of flowers.
No pruning is required, making it an ideal choice for gardeners seeking low-maintenance options.

Tips

To ensure the health and vitality of your Polemonium caeruleum, it is important to maintain moist soil conditions, as the plant is not drought-resistant. Submerging the pot in water until thoroughly soaked is an effective method to achieve this.
Propagation can be easily achieved through the sowing of seeds or by division to promote new growth and maintain plant health. It is recommended to perform division either in spring or autumn for optimal results.
When situating Jacob's ladder in your garden, take care to choose a location that receives full sun to partial shade to accommodate its light requirements and encourage a full display of flowers.

Ideal placement of a Polemonium caeruleum

The plant thrives best in locations that offer full sun to partial shade, ensuring an optimal display of its striking blue flowers during the blooming months. While adaptable to all soil types, it's imperative that the soil is well-drained to prevent waterlogging, which this species does not tolerate well. To accommodate its upright growth habit and eventual height of 60 cm, ensure it is placed where it has room to flourish without overshadowing shorter companions in a border or group planting. Regular watering is essential, with a preference for submerging to meet its hydration needs.

How do I plant a Polemonium caeruleum?

For optimal growth, Polemonium caeruleum thrives in well-drained soil, in a location receiving full sunlight to partial shade. When planting this species, ensure the soil is moist and that each individual is given enough space to reach its full height of 60 cm and spread its upright growth. The root system, already established in pots, should be submerged in water before being placed in the ground to encourage a strong transition. Planting is best done during the cooler months of spring or autumn to minimize stress on the plant. Regular watering is necessary to maintain the health of this deciduous species, especially during dry spells.

Pruning a Polemonium caeruleum

Polemonium caeruleum is a low-maintenance species that typically requires no pruning to flourish. Its upright growth habit naturally leads to a pleasing form without intervention. However, should gardeners wish to tidy up the appearance or remove spent flowers, deadheading after blooming may encourage a second flush of flowers. At the end of the growing season, as this deciduous plant prepares for dormancy, old foliage can be cleared away to keep the area neat and to prepare for new growth in spring.

Watering a Polemonium caeruleum

To ensure the Polemonium caeruleum thrives, consistent moisture is key. It is recommended to submerge the pot in water, allowing the soil to absorb moisture from the bottom up until it is evenly saturated. This method promotes a deeper water penetration, which is beneficial for the development of a strong root system. During the active growing season, particularly in the warmer summer months, this species may require more frequent watering to maintain its lush, green foliage. As with all plants, well-drained soil is essential to prevent waterlogging and ensure optimal health.

Fertilising a Polemonium caeruleum

To ensure the vigorous health and lush blooms of Polemonium caeruleum, it is recommended to fertilize it periodically. Apply a balanced, slow-release fertilizer at the onset of the growing season in early spring to kickstart the plant's growth cycle. A second application of fertilizer can be beneficial in mid-summer to sustain the plant's needs during its peak flowering period.

Given that Polemonium caeruleum thrives in well-drained soil, care should be taken to ensure that fertilizer is well incorporated and that the soil is not waterlogged, which could impede nutrient uptake. Opt for a fertilizer that is suited for a wide range of plants to maintain the plant's striking blue flowers and robust, upright growth habit. Regular fertilization, following the specific instructions on the product, will contribute to the plant's overall health and longevity.

The characteristics of a Polemonium caeruleum

Known for its elegant, ladder-like leaf arrangement, Polemonium caeruleum is a delightful addition to any garden. An intriguing aspect of this species is its ability to thrive in partially shaded areas, where other plants may struggle. This makes it an excellent choice for bringing life and color to underutilized spaces. The charming bell-shaped flowers offer a serene blue hue, which can provide a calming effect in a garden setting. Additionally, being potted, it allows for easy relocation to suit your garden's evolving design.

Separating/dividing a Polemonium caeruleum

To ensure continued health and vigor, Polemonium caeruleum benefits significantly from division every few years. This process not only stimulates new growth but also helps maintain the plant's vitality. Carefully lift the plant from the soil, gently teasing it apart into smaller sections, each with its own root system. Replant these divisions promptly, allowing adequate space for future growth. Ideally, perform this task in the cooler temperatures of spring or autumn to minimize stress on the plant and to give it the best chance for establishing itself before the onset of extreme weather.

What will be the height of Polemonium caeruleum?

Polemonium caeruleum typically grows to a height ranging between 50 centimeters and 1 meter.

What will be the width of Polemonium caeruleum?

Polemonium caeruleum will reach a maximum spread of 10 to 50 centimeters at maturity.

Which soil type is most suitable for the Polemonium caeruleum?

Polemonium caeruleum is adaptable to various soil types, but it particularly favors well-drained soils. This ensures that the plant's roots are not waterlogged, promoting healthier growth and development.

What is the ideal positioning for the Polemonium caeruleum?

Polemonium caeruleum thrives in locations with both sun and partial shade. This plant is adaptable to various light conditions, making it suitable for areas with direct sunlight as well as spots where sunlight is partially filtered.

What is the flowering colour of the Polemonium caeruleum?

The flowers of Polemonium caeruleum display a lovely blue hue, adding a delightful touch of color to this plant.

Is the Polemonium caeruleum hardy?

Polemonium caeruleum is indeed winter hardy. It can tolerate temperatures as low as -23.3°C to -20.1°C, falling within the USDA zone 6a. This indicates that Polemonium caeruleum is well-equipped to endure cold winter conditions typical of many regions.

Is the Polemonium caeruleum evergreen?

Polemonium caeruleum is not an evergreen plant. It sheds its leaves during certain seasons and regrows them under suitable conditions.

What is the growth strength of the Polemonium caeruleum?

Polemonium caeruleum achieves its full height within a span of 2 to 5 years, indicating a moderate growth rate that allows for steady and consistent development over a few years.

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