PL. —Polemonium carneumBotanical illustration — drop image
Polemonium carneum

Great Jacob's Ladder

SpringSummer
5a8bHardiness zone
Peak bloom windowZone 6b · frost-offset weeks
Winter
Not in bloom
Spring
Peak bloom
Summer
In bloom
Fall
Not in bloom
Peak bloom
In bloom
Background

Polemonium carneum is a Pacific Northwest native perennial with pinnate, ladder-like foliage and loose clusters of soft pink to salmon flowers in late spring and early summer. It grows naturally along forest margins, moist meadows, and shaded slopes west of the Cascade crest, from Washington through Oregon to the San Francisco Bay Area.

It performs best in cool, moist sites with dappled shade and steady soil moisture. Summer heat and drought push it into early dormancy; in the warmer part of its range, afternoon shade and a layer of organic mulch help it persist. The plant self-seeds modestly and can be divided every two to three years in early fall to maintain vigor. Humus-rich soil with good drainage is essential, as standing water promotes crown rot.

As a regional native, it provides early-season pollen and nectar to native bees and bumblebees and integrates naturally into shaded rain gardens and woodland edge plantings throughout the Pacific Northwest.

Care guide
SunPart shade to full shade
WaterConsistent moisture
SoilMoist, well-drained, humus-rich
Spacing12–18 in
Height18–30 in
Zone5a – 8b
Native RegionCA, OR, WA
Direct sowFrost hardy
Seasonal tasks
winter
sowStart seeds indoors in cool, moist conditions 8–10 weeks before last frost; cold-stratify seeds for 2–4 weeks in the refrigerator before sowing to improve germination.
spring
cutRemove spent flower stalks promptly after the main bloom flush to encourage a second flush and limit unwanted self-seeding.
sowDirect sow seeds outdoors in early spring while soil remains cool; surface sow and press lightly into soil without covering, as seeds need light to germinate.
summer
cutDivide crowded clumps in early fall every two to three years; replant divisions at the same soil depth and water in well.
watchWatch for powdery mildew during warm, humid spells; improve air circulation and avoid wetting foliage when irrigating.
cutCut back yellowed or dormant foliage to ground level in midsummer; the plant may produce fresh growth again in fall as temperatures cool.
fall
watchMonitor for leaf spot lesions during wet fall weather; remove and dispose of affected foliage and avoid overhead irrigation.
Common problems

Powdery mildew

Symptoms

White or grey powdery coating on leaves — usually starting on older growth in humid conditions or when nights cool.

Treatment

Improve air circulation by thinning plants. Apply neem oil or potassium bicarbonate spray at first sign. Avoid overhead watering.

Fungal leaf spot

Symptoms

Brown or purplish spots on the leaves, often ringed with a yellow halo, that spread and merge in warm, humid, or wet weather; heavily spotted leaves yellow and drop early.

Treatment

Pick off spotted leaves and clear fallen debris to remove overwintering spores. Improve air circulation by thinning, and water at the base so foliage dries quickly. If it persists, apply a copper- or sulfur-based fungicide at the first sign.

Crown Rot

Symptoms

Lower leaves yellow and wilt; the base of the rosette turns brown and soft, sometimes with white fungal threads at the soil line. Plants collapse in wet conditions.

Treatment

Remove and destroy affected plants. Improve drainage and avoid overhead watering. Do not mulch directly against the crown. Space plants for airflow and avoid replanting in the same wet spot.

From the field journal