The Marvelous Shrubby St John’s Wort Plant
The shrubby St. John’s wort plant also known by its scientific name Hypericum prolificum is a gorgeous and versatile native plant that makes an excellent addition to any garden. In this article, we will explore everything you need to know about growing and caring for this underutilized gem.
Description
The shrubby St. John’s wort is a deciduous shrub which typically grows 1-4 feet tall with a rounded, dense growth habit. It features clusters of bright golden yellow flowers that bloom from early to mid summer. The flowers have a 5-petaled shape and are about 1 inch in diameter. Each flower has a prominent burst of bushy yellow stamens that partially obscure the petals, giving rise to the species name “prolificum” which refers to the prolific stamens.
The leaves are narrow and oblong, about 1-3 inches long and 1/4 to 1/2 inch wide. They are medium to dark green. In autumn, the cone-shaped seed capsules split open to reveal many small black seeds. The bark on older stems exfoliates to expose an attractive pale orange inner bark.
Native Range and Habitat
The shrubby St. John’s wort is native to central and eastern North America. Its natural habitats include rocky ground, dry wooded slopes, fields, stream banks, and moist valleys. It is naturally adapted to a variety of environmental conditions.
Growing Conditions
This plant is easy to grow and adaptable to various soil types and moisture levels. It thrives in full sun to partial shade. It tolerates dry conditions but also grows well in medium moisture. It can handle environmental stressors like drought, erosion, heat, humidity, and poor soils including rocky, sandy, or clay soil types.
The shrubby St. John’s wort can be grown successfully in USDA Plant Hardiness Zones 3-8.
Uses in the Landscape
This shrub has a naturally rounded shape but can be pruned in early spring to maintain a fuller, mounded form. It makes an excellent addition to native plant gardens, mixed borders, mass plantings, foundations, hillslopes, and more. It can be used as an informal hedge or property border.
Some specific ways to utilize the shrubby St. John’s wort in the landscape include:
- Mass planting along foundations or property borders
- Grouped in the shrub border
- Planted on banks or slopes to control erosion
- Incorporated into native wildflower gardens to add color
- Used as a flowering hedge or screening plant
- Planted in groupings amid ornamental grasses
The shrubby St. John’s wort flowers make beautiful cut arrangements. The dried seed pods can also be used in dried floral crafts.
Care and Maintenance
Caring for the shrubby St. John’s wort is easy. It requires minimal care once established. To boost its performance, provide supplemental water during periods of drought, especially in the first year after planting. Prune every few years in early spring to shape and renew growth. Other than that, this plant is quite tough and self-sufficient.
It has no major pest or disease issues. Deer and rabbits tend to avoid it. The shrubby St. John’s wort has natural defenses including compounds that irritate the digestive tracts of mammals that try to munch on it.
How to Plant
You can start shrubby St. John’s wort from seed, cuttings, or nursery transplants. Seeds can be directly sown outdoors in late fall or winter. They require a period of cold, moist stratification before they will germinate. No pretreatment is needed for spring planting. Nursery transplants should be planted in spring once the threat of frost has passed. Space plants 2-4 feet apart depending on the intended size. Amend the soil with compost or peat moss to improve moisture retention. Water transplants regularly the first season to establish an extensive root system. Apply a layer of mulch around transplants to conserve moisture and suppress weeds.
Benefits for Pollinators and Wildlife
The shrubby St. John’s wort is an outstanding plant for pollinators including native bees, honeybees, butterflies, and more. It provides nectar as well as pollen which is collected for bee bread. Bumblebees are especially attracted to the bright yellow flowers.
Birds eat the seeds and use the shrub for protective cover. Various moth and butterfly caterpillars use the shrubby St. John’s wort as a host plant. All in all, this plant contributes valuable resources for wildlife in the landscape.
Why Grow Shrubby St. John’s Wort
Here are some of the top benefits of growing this marvelous plant:
- Beautiful and long-lasting golden yellow blooms
- Excellent for pollinators
- Attractive exfoliating bark adds winter interest
- Deer and rabbit resistant
- Tolerates heat, humidity, drought, and poor soil
- Long flowering period from early to mid summer
- Adaptable and tough once established
- Works well in wildflower gardens, borders, etc.
- North American native plant with conservation value
Exploring Nature’s Connections Search
For about eight weeks during the summer, Shrubby St. Johnswort (Hypericum prolificum) is decorated with flowers, like ornaments on a holiday tree in mid-summer.
Each bright yellow blossom has five petals that provide a backdrop to a sphere-shaped burst of stamens, the male reproductive parts of the flowers. Reaching out for a pollen deposit from the very center of the flowers are their female reproductive parts, called pistils.
This gaudy display is attractive to me, but more importantly, it’s a very effective lure for potential pollinators. Bumble Bees are among the most likely visitors and effective pollinators. While they climb around the stamens, eating and harvesting pollen from the anthers at their tips, they also pick up quite a bit of pollen on their hairy bodies. As they forage, pollen on their bodies may be brushed off on the stigma at the tip of a flower’s pistil, setting the wheels in motion for pollination to occur.
Female bees eat pollen themselves, and they also collect pollen to bring back to their nests to feed their larvae. In the photo below, you can see the ‘bee bread’ this female has collected on her hind legs. Quite a haul!
Other bees, like Sweat Bees, also visit the flowers for their pollen.
Flies are also consumers of pollen. Flower Flies (also called Syrphid flies or Hover flies) are among those attracted to this pollen banquet. They may also help with the pollination process, although their bodies are not as hairy as many of the bees.
This bounty of pollen is so successful in enticing insects for whom pollen is an important part of their diet, primarily bees and flies, that Shrubby St. Johnswort doesn’t expend any energy producing nectar, finding it unnecessary to do so.
If the inadvertent pollination activities of these insects provide the expected payoff, this shrub lives up to the designation ‘prolificum’ in its scientific name, becoming ‘very fruitful’. Fruit capsules replace the flowers, eventually opening to release their seeds for dispersal by gravity, or by hitching a ride on a passing animal. These dry fruits are visible throughout winter and into the following spring.
Shrubby St. Johnswort is related to the more well-known Common St. Johnswort (Hypericum perforatum), which is used for many medicinal purposes. Shrubby St. Johnswort shares at least one chemical compound, hypericin, with its more famous relative. Hypericin has a photosensitizing effect on its consumers, that is, it makes the skin of the animal that eats it especially sensitive to the sun, and exposure to sunlight after consumption results in rashes. Producing hypericin evolved as an effective deterrent to animals that might otherwise be tempted to eat this plant, including deer.
Shrubby St. Johnswort is a relatively compact deciduous shrub that can grow to a height of about 6.5 feet (2 meters). It does well in a variety of soils, from dry and rocky to moist, and can tolerate full sun to part shade. Shrubby St. Johnswort is native in the eastern half of the United States, and in the province of Ontario in Canada.
Resources
Eaton, Eric R.; Kauffman, Ken. Kaufman Field Guide to Insects of North America. 2007.
Eastman, John. The Book of Field and Roadside. 2003.
Hoffmann, David. Medical Herbalism. 2003.
Rhoads, Ann Fowler; Block, Timothy A. The Plants of Pennsylvania. 2007
Stearn, William T. Stearn’s Dictionary of Plant Names. 1996
St Johns Wort groundcover Hypericum calycinum – pollinator friendly flowering evergreen groundcover
FAQ
How big do shrubby St John’s wort get?
Shrubby St. John’s Wort is a medium sized shrub, up to 4 feet high and wide. The naturally mounded form, covered in a dense foliage of small slender leaves, is easily pruned into a nice rounded shape in early spring.
What is the difference between St. John’s Wort and shrubby St. John’s Wort?
Shrubby St. John’s Wort has a more open habit, the leaves are larger, and the flowers are also larger and less likely to bloom in clusters. Kalm’s St. John’s Wort is the smallest (growing 2-3 feet).
What are the best uses for shrubby St. John’s Wort?
St. John’s wort is anti-inflammatory that can be used topically for wounds, bruises, varicose veins, sore muscles and mild burns. I have two favorite topical uses for this plant: for sunburn and for nerve damage from disease or blunt-force trauma.
Where to plant shrubby St. Johns Wort?
Grow in full sun to light shade in dry to medium moist soil. Blooms on new growth; prune in early spring. Root rot and wilt can be a problem during hot humid weather.