Hypericum calcycinum, Aaron’s beard, or creeping St. John’s wort is a stoloniferous subshrub typically growing to a height of 12 inches and a width of 24 inches. This is a plant you are going to see frequently planted as a ground cover.
This St. John’s wort features large, rose-like, 5-petaled, yellow flowers (2 to 3 inches across) having numerous, bushy stamens with reddish anthers. Flowers appear singly or in groups of 2 to 3 and cover the plant in summer. Oval to oblong, distinctively net-veined (from beneath) leaves (4 inches in length) are rich green in sun but are a lighter, yellowish green in shade. Four-angled stems are both procumbent and ascending.
How to Make Your Hypericum Calcycinum, Creeping St. John’s Wort Thrive
Hypericum calcycinum is easily grown in average, medium, well-drained soil in full sun to part shade. It tolerates wide range of soils, but it thrives in sandy soils in full sun. If planted in shade flower production decreases. St. John’s Wort is evergreen in warm winter climates (it is evergreen in Seattle’s Zone 8 gardens); it 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 you should shear or mow plants in late winter or early spring every 2 to 3 years to renew and induce new growth.
This plant spreads rapidly by underground stems and can be aggressive in ideal growing conditions; plant about 18 inches apart when you are using it as a ground cover.
General Hypericum Calcycinum, Creeping St. John’s Wort Information
Pests and Diseases
No serious insect or disease problems.
You can reliably propagate from softwood cuttings in spring, division in early spring, and of course seeds.
Ideal when used as a ground cover, in rock gardens, border fronts, naturalized plantings; it is also a great choice for stabilizing embankments or hillsides. Good for planting under trees where it competes well with shallow tree roots.
- Family: Hypericaceae
- Common Name: St. John’s wort
- Type: Deciduous shrub (evergreen in warmer climates)
- Hardiness Zones: Zones 5 to 9
- Height: 12 to 18 inches
- Spread: 18 to 24 inches
- Bloom Time: July to August
- Bloom Description: Bright yellow
- Sun: Full sun to part shade
- Water: Medium
- Maintenance: Low
- Suggested Uses: Ground Cover (considered invasive in some parts of the U.S.)
- Tolerate: Drought, erosion, dry Soil