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Hypericum kalmianum (Kalm St. John’s Wort)

Kalm St. John's Wort

Award General
Hypericum Kalmianum, Kalm St. John's Wort, Evergreen Shrub, yellow flowers, Hypericum, St John's Wort
Hypericum Kalmianum

Compact and easy to grow, Hypericum kalmianum (Kalm St. John’s Wort) is a small semi-evergreen shrub with showy, golden yellow flowers blooming for about 6 weeks in mid to late summer. They are borne in flat clusters of 3-7 flowers, at the tips of upright branching stems. Each cup-shaped flower presents 5 petals surrounding a prominent tuft of golden stamens. Rich in nectar, they are a favorite of butterflies, bumblebees, or other pollinators and are excellent for cutting. They are followed by chocolate, oval seed heads in fall, which often persist until spring, but are of limited ornamental interest. The foliage of linear dark blue-green leaves provides a lovely backdrop for the bright golden blossoms.

  • This broadleaf semi-evergreen shrub has a dense, rounded habit and grows at a slow rate, up to 2-3 ft. tall with an equal spread (60-90 cm)
  • A full sun to part shade lover, this plant is easily grown in medium moisture, well-drained soils. Prefers moist, rich, sandy loams but tolerates poor, rocky or wet soils. Drought and salt-tolerant.
  • Winner of the GreatPlants award, which is a joint effort between the Nebraska Nursery, Landscape Association and the Nebraska Statewide Arboretum. The goal of this award is to identify superior ornamental landscape plants that meet the challenging growing conditions of the region.
  • Low maintenance, this plant is also generally pest and disease-free.
  • Perfect as a specimen or massed in borders, rock gardens, slopes, and naturalized areas. Makes an excellent low hedge.
  • If pruning is required, cut back to shape in late fall, but do not cut back all the way to the ground.
  • Native to the Great Lakes region of the U.S.

Requirements

Hardiness 4 - 7
Climate Zones 2, 2A, 2B, 3, 3A, 3B, 4, 5, 6, 7, 10
Plant Type Shrubs
Plant Family Hypericaceae
Genus Hypericum
Common names St. John's Wort
Exposure Full Sun, Partial Sun
Season of Interest Summer (Mid, Late)
Height 2' - 3'
(60cm - 90cm)
Spread 2' - 3'
(60cm - 90cm)
Spacing 24" - 36"
(60cm - 90cm)
Maintenance Low
Water Needs Average
Soil Type Clay, Loam, Sand
Soil pH Acid, Alkaline, Neutral
Soil Drainage Moist but Well-Drained, Well-Drained
Characteristics Cut Flowers, Plant of Merit, Showy, Semi-Evergreen
Native Plants United States, Northeast, New York, Ohio, Midwest, Michigan, Wisconsin, Indiana, Illinois
Tolerance Drought, Salt, Rocky Soil, Wet Soil
Attracts Bees, Birds, Butterflies
Garden Uses Banks And Slopes, Beds And Borders, Hedges And Screens
Garden Styles Prairie and Meadow, Gravel and Rock Garden, Informal and Cottage
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Alternative Plants to Consider

Hypericum densiflorum (Bushy St. John’s Wort)
Hypericum ascyron (Great St. John’s Wort)
Hypericum prolificum (Shrubby St. John’s Wort)
Hypericum kalmianum Cobalt-n-Gold™ (Kalm St. John’s Wort)
Hypericum x hidcoteense ‘Hidcote’ (St. John’s Wort)
Hypericum frondosum ‘Sunburst’ (St. John’s Wort)

Recommended Companion Plants

Crocosmia (Montbretia)
Agastache (Hyssop)
Echinops (Globe Thistle)
Rudbeckia fulgida (Black-Eyed Susan)
While every effort has been made to describe these plants accurately, please keep in mind that height, bloom time, and color may differ in various climates. The description of these plants has been written based on numerous outside resources.
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Requirements

Hardiness 4 - 7
Climate Zones 2, 2A, 2B, 3, 3A, 3B, 4, 5, 6, 7, 10
Plant Type Shrubs
Plant Family Hypericaceae
Genus Hypericum
Common names St. John's Wort
Exposure Full Sun, Partial Sun
Season of Interest Summer (Mid, Late)
Height 2' - 3'
(60cm - 90cm)
Spread 2' - 3'
(60cm - 90cm)
Spacing 24" - 36"
(60cm - 90cm)
Maintenance Low
Water Needs Average
Soil Type Clay, Loam, Sand
Soil pH Acid, Alkaline, Neutral
Soil Drainage Moist but Well-Drained, Well-Drained
Characteristics Cut Flowers, Plant of Merit, Showy, Semi-Evergreen
Native Plants United States, Northeast, New York, Ohio, Midwest, Michigan, Wisconsin, Indiana, Illinois
Tolerance Drought, Salt, Rocky Soil, Wet Soil
Attracts Bees, Birds, Butterflies
Garden Uses Banks And Slopes, Beds And Borders, Hedges And Screens
Garden Styles Prairie and Meadow, Gravel and Rock Garden, Informal and Cottage
How Many Plants
Do I Need?
Not sure which Hypericum (St. John's Wort) to pick?
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