How to Grow Polemonium Plants

Guide to Growing Jacob's ladder, Greek Valerian, Charity, and Abscess Root

Polemonium are hardy perennials that range in height from 15 to 90 cm (6 to 36 inches).

They bloom from the end of spring to summer with blue, yellow, pink or white cup shaped flowers.

One of the common names for Polemonium is Jacob's Ladder.

Polemonium pulcherrimum
Polemonium pulcherrimum by brewbooks.

Polemonium Growing and Care Guide

  • Common Names: Jacob's ladder, Charity, Greek Valerian, Sky Pilot, Abscess Root.
  • Life Cycle: Hardy perennial. Some are hardy annuals.
  • Height: 4 to 48 inches (10—120 cm).
  • Native: Northern Hemisphere. South America.
  • Growing Region: Zones 3 to 8.

  • Flowers: Late spring through to summer.
  • Flower Details: White, blue, pink, yellow. Cup-shaped. Five petals.
  • Foliage: Herbaceous. Clump-forming. Pinnate. Dark green.

  • Sow Outside: Cover seed. Start of spring or the beginning of autumn.
  • Sow Inside: Germination time: three to four weeks. Temperature: 70°F (21°C). Start eight to ten weeks in advance. Transplant outdoors following the last deep frost, but when a light frost is still possible, or at the beginning of autumn. Spacing 10 to 24 inches (25 to 60 cm).

  • Requirements and care: Partial shade, can tolerate full sunlight in colder areas. Good drainage. Rich, moist soil. pH 5 to 8. Water during prolonged dry spells. In the spring supply a top dressing of cow manure or leaf mold mulch. Cut back to the ground once flowering has completed. Propagate: by dividing in the spring, or preferably allow to self-seed as plant roots are quite delicate.
  • Family: Polemoniaceae.
  • Closely Related Species: Phlox.
  • Miscellaneous: Roots are often used as herbal remedy for coughs and inflammations. Attracts the Coleophora polemoniella moth.

How to Grow Jacob's Ladder and other Polemonium

The seeds of Polemonium can be sown outdoors at the start of spring or autumn. Once sown lightly cover the seed.

The plants should have a spacing of about 20 to 30 cm (8 to 12 inches) small Polemonium species) or 45 to 60 cm (18 to 24 inches) larger Polemonium varieties).

They should ideally be grown in a location that is a partially shaded part of the garden. this should have a rich, moist soil that is kept cool and well drained, and has a pH of 5 to 8.

If you plan to first grow Jacob's ladder indoors, then start about two months in advance.

It should take about three or four weeks for the Jacob's ladder seeds to germinate at a temperature of 21 degrees centigrade (70°F).

Once ready, the young plants should be transplanted into the garden either at the start of autumn, or just before the last frost of spring.

Caring for Polemonium

Jacob's ladder and other Polemonium species are fairly easy to care for. They enjoy a moist soil, so water frequently.

The soil should be kept cool, so it is best to top dress the soil with leaf mold in the spring. Once flowering has finished cut the flowering shoots back to ground level.

If you require further Polemonium plants, then they can be propagated by carefully division in the spring. Or allow them to self and set seed in situ.

I hope that you enjoyed this guide on how to grow Polemonium plants. You may also enjoy the following Gardener's HQ growing guides: How to grow Gilia, Alchemilla alpina, Leontopodium plant, and Cobaea plants.