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Hypericaceae
Trees and shrubs
Kalm's St. John's Wort 'Cobalt-N-Gold'
Hardiness
Zone 4
Discover the plant
Family
Hypericaceae
Hypericum kalmianum ‘Cobalt-N-Gold’ is a compact and extremely decorative ornamental shrub, prized for the striking contrast between its bluish foliage and abundant bright yellow blooms. This selection stands out with its narrow, steel-blue leaves with cobalt reflections, which beautifully highlight the numerous star-shaped golden-yellow flowers with prominent stamens appearing in summer. Its overall habit is rounded, dense, and naturally well-branched, with a silhouette that is wider than it is tall, ideal for sunny borders, foreground plantings, and group plantings. The deciduous to semi-evergreen foliage, depending on the climate, provides a fine and modern texture throughout the season. Very hardy, drought-tolerant once established, and low-maintenance, ‘Cobalt-N-Gold’ is particularly well-suited for northern gardens, sustainable landscaping, and exposed sites where reliability is essential.
Soil and care
The rightconditions.
Fertilization
Low, rarely needed
Bloom and dimensions
The completeprofile.
Bloom periodSummer
Flower colorBright yellow
Foliage colorSteel blue with cobalt reflections
Foliage typeDeciduous to semi-evergreen
FruitingDiscrete brownish capsules of no ornamental interest
Maximum height0.6–0.9 m (2–3 ft)
Maximum width3–4 ft (0.9–1.2 m)
Growth rateModerate
Hardiness zoneZone 4
Minimum temperature-40°C
Its strengths, naturally.
Not recommended for pets
Pets
Attracts or supports pollinating insects
Pollinators
Plants that attract butterflies
Butterflies
Less attractive or generally tolerated by deer
Deer
