Hypericum calycinum
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Tried and True Recommended by 1 Professional
Common Name: St. John's wort
Type: Deciduous shrub
Family: Hypericaceae
Zone: 5 to 9
Native Range: Southern Europe, southwestern Asia
Garden Location: Cornelia Sunnen Backyard Garden, Lois Whiteside Franklin Flower Trial Garden, Ameren Ground Cover Border, Jordan Charitable Foundation Ornamental Shade Garden and Overlook
Height: 1 to 1.5 feet
Spread: 1.5 to 2 feet
Bloom Time: July to August
Bloom Color: Yellow
Bloom Description: Bright yellow
Sun: Full sun to part shade
Water: Medium
Maintenance: Low
Flowers: Showy Flowers
Tolerates: Dry Soil, Drought
Uses: Groundcover, Erosion Control

Culture

Easily grown in average, medium, well-drained soil in full sun to part shade. Tolerates wide range of soils. Thrives on sandy soils in full sun. Less floriferous in part shade. Evergreen in warm winter climates. Usually dies to the ground or suffers some tip dieback in cold winter climates, but blooms on new growth and comes back nicely each spring. In areas where it does not die in winter, shear or mow plants in late winter or early spring every 2-3 years to renew and induce new growth. Spreads rapidly by underground stems and can spread aggressively in ideal growing conditions. Plant 18" apart for use as a ground cover.

Noteworthy Characteristics

A stoloniferous subshrub or shrublet, typically growing 12" (less frequently to 18") high and 24" wide, which is frequently planted as a ground cover. Features large, rose-like, 5-petaled, yellow flowers (2-3" diameter) having numerous, bushy stamens with reddish anthers. Flowers appear singly or in groups of 2-3 and cover the plant in summer. Oval to oblong, distinctively net-veined (from beneath) leaves (to 4" long) are rich green in sun but are a lighter, yellowish green in shade. Four-angled stems are both procumbent and ascending. Sometimes commonly called Aaron's beard or creeping St. John's wort. Plants of the genus Hypericum (some species have been used since ancient times in the treatment of wounds) were apparently gathered and burned to ward off evil spirits on the eve of St. John's Day, thus giving rise to the genus common name of St. John's wort.

Plant of Merit

Large, saucer-shaped, 5-petaled, bright yellow flowers with distinctively protruding bushy stamens cover this dense shrubby ground cover with spectacular bloom in summer. It typically grows 12–15 inches tall and spreads indefinitely by creeping stems clad with leathery, rich green leaves. Foliage often survives winter, but established plantings are best sheared/pruned annually in early spring to encourage vigorous new foliage growth.

Problems

No serious insect or disease problems.

Garden Uses

Ground cover, rock gardens, border fronts, naturalized plantings. Also good for stabilizing embankments or hillsides. Good for planting under trees where it competes well with shallow tree roots. Allan Armitage calls this "one of the finest ground covers available."

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