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Polemonium spp.

Jacob's ladders

Polemoniaceae Northern Hemisphere

Attracts Pollinators Attracts Butterflies Container Friendly

Native to North America

SunFull Sun – Part Shade

WaterMedium

HardinessZones 3–8

Overview

Polemonium spp. is a genus of about 25-40 species of mostly perennial herbs in the phlox family, native to cool temperate regions of the Northern Hemisphere and the mountains of South America. The pinnate leaves, with leaflets arranged in opposite pairs along the stalk, resemble the rungs of a ladder and give rise to the common name Jacob's ladder. Plants form basal clumps and upright flowering stems 15-90 cm (6-36 in) tall, depending on species. The bell- to cup-shaped flowers, 1-2 cm (0.4-0.8 in) across, are usually blue or violet, sometimes white or pale yellow, with prominent yellow or orange stamens, and are carried in loose terminal clusters. Species grow in moist meadows, woodland edges, streambanks, and alpine slopes. Most need cool, moist conditions and decline in hot, dry summers, when foliage can scorch or go dormant. Garden forms of species such as P. caeruleum and P. reptans are grown for their spring and early-summer flowers.

Native Range

Polemonium spp. is native to the Northern Hemisphere, ranging across North America, Europe, and northern Asia, with a few species in the Andes of South America. Species occupy cool habitats including mountain meadows, moist woodland, and northern grassland.

Suggested Uses

Polemonium spp. is planted in cottage gardens, woodland edges, mixed borders, and streamside plantings in cool climates. The spring flowers support bees and other pollinators. Lower species suit the front of borders and rock gardens, spaced 30-45 cm (12-18 in) apart.

How to Identify

Identify Polemonium spp. by its pinnate, ladder-like leaves with paired leaflets and its loose clusters of blue, violet, or white bell-shaped flowers with five lobes. The flowers have five stamens with often orange anthers. The ladder-leaf arrangement separates it from related phlox-family plants with simple leaves.

Appearance

Size & Dimensions

Height6" - 3'

Width/Spread1' - 2'

Colors

Flower Colors

Foliage Colors

Fall Foliage Colors

Bloom Information

Bloom Period

~4 weeks

Spring Summer

Most species flower in late spring and early summer, roughly May-July, with alpine species blooming as snow recedes. The flower clusters open over several weeks. Some species rebloom lightly if cut back after the first flush.

Detailed Descriptions

Flower Description

blue to violet

Foliage Description

green

Growing Conditions

Sun Requirements

SunFull Sun SunPartial Shade

Requires 4-8 hours of direct sunlight daily

• Full Sun: 6+ hours of direct sunlight

• Partial Shade: 3-6 hours of direct sunlight

• Full Shade: Less than 3 hours of direct sunlight

Soil Requirements

pH Range6.0 - 7.5(Neutral)

357912

Soil Types

loam clay

Drainagemoist

Water & Climate

Water Needs

Medium

Frost Tolerance

hardy

Time to Maturity

1-2 years

Care & Maintenance

Care Guide

Polemonium spp. grows in full sun to part shade in moist, fertile, well-drained soil rich in organic matter. Plants need consistent moisture and tolerate neither prolonged drought nor waterlogging; in hot climates afternoon shade reduces leaf scorch. A soil pH around 6.0-7.5 suits most species. They are cold-hardy, many to USDA zone 3, and die back in winter. Dividing clumps every few years in spring keeps them vigorous. Foliage may decline in midsummer heat and regrow in cooler weather.

Pruning

Cutting back spent flower stems after bloom keeps plants tidy and can prompt a second, lighter flush. Removing tired summer foliage encourages fresh basal growth. Stems are cut to the ground in late autumn once dormant.