Botanical profile

Hypericum kalmianum

Latin name
Hypericum kalmianum
Common name
Kalm's St. John's Wort
Type
Ornamental shrub
Family
Hypericaceae

Hypericum kalmianum is a compact and very hardy ornamental shrub, valued for its abundant bright yellow flowers and high tolerance to difficult conditions. This North American species is distinguished by its numerous star-shaped golden-yellow flowers with prominent stamens, which appear in summer and strongly attract pollinators. Its general habit is rounded, dense, and naturally well-branched, with a wider than tall silhouette, making it an excellent choice for borders, foreground plantings, and group plantings. The deciduous to semi-evergreen foliage, depending on the climate, is bluish-green and provides a fine and decorative texture throughout the season. Very hardy and easy to maintain, Hypericum kalmianum is particularly appreciated for sustainable landscaping, naturalistic gardens, and exposed areas where few shrubs thrive long-term.

Care guide

Growing conditions

Light, soil, water and hardiness

Hardiness zone
Zone 3
Exposure
Sun
Watering
Low to moderate
Fertilization
Low, rarely needed
Soil type
Ordinary, well-drained, tolerates poor soils
Minimum temperature
-40°C
Plant appearance

Blooming, foliage and shape

Blooming period
Summer
Flower color
Bright yellow
Fruiting
Discrete brownish capsules of no ornamental interest
Foliage color
Blueish green
Foliage type
Deciduous to semi-evergreen
Shape
Compact, rounded, and dense shrub
Garden structure

Size and growth

Height
2–3.3 ft (0.6–1 m)
Width
3–4 ft (0.9–1.2 m)
Growth rate
Moderate
Not recommended for pets
Not recommended for pets

Pets

Pollinators
Attracts or supports pollinating insects

Pollinators

Butterflies
Plants that attract butterflies

Butterflies

Deer
Less attractive or generally tolerated by deer

Deer

The availability of our plants varies depending on arrivals, seasons, nursery production and supplier availability. Some varieties may be offered for a limited time only, depending on their natural cycle or current stock. These plant profiles are designed to guide and inspire you when choosing plants for the garden, landscaping projects, containers or long-lasting outdoor arrangements.