St. John’s Wort  (Hypericum perforatum)

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St. John’s Wort  (Hypericum perforatum)

Common Names

Qian Ceng Lou,  Klamath Weed, Goatweed, Tipton Weed, Common St. Johnswort, Rosin-Rose

About This Plant

Loved for its sunny disposition and bright yellow blossoms, St. John’s Wort is a hardy perennial shrub found in USDA zones 5 through 9. It is a short plant, often about one foot high, but can grow up to about three feet tall. It has barren shoots and erect stems that branch on their upper portions. St. John’s Wort can be found growing in the wild in dry grasslands, pastures, sun-exposed slopes, sparse woods, and along roadways.


Its leaves are pale-green in color, oblong, and spade-like and sparsely cover its multi-branched stems.  The leaves are smooth to the touch and have smooth edges. When holding the leaves up to the light, you can see small, black, translucent dots that at first glance may look like small perforations or holes.  These are actually glands that when pressed release distinctive red-colored essential plant oils and resins.


St. John’s Wort stems are woody near their bases and may appear jointed from leaf scars.  Two longitudinal lines or ridges run along the edge of the stem which make it appear to be pressed flat.  The plant produces bright yellow, five-petaled blossoms with protruding tufts of yellow stamens.  They blossom at the height of Summer, when the days are the longest, from June to August.  The plants produce numerous flowers with roughly 25-100 blooms per stem.  When squeezed, the flowers too will “bleed” a reddish liquid that stains the fingers.


The small, round, blackish seeds are contained in a three-celled capsule that turn a deep reddish brown as it matures and has a resinous smell. The plant is pollinated by bees and flies, making it well-suited for a pollinator restoration habitat. The seeds can remain viable in the soil for up to ten years and thus St. John’s Wort is often part of the “seek bank” of forested areas.


Its roots consist of extensive creeping rhizomes.  The long, slender “runners” or stems grow at the soil surface level or just below it.  It also has taproots that extend two to five feet deep, making it a good option for an erosion control plant. The roots are colonized with vesicular-arbuscular mycorrhizal fungi (VAM) which makes the plant more tolerant of harsh environmental conditions.


St. John’s Wort has long enjoyed a colorful past.  It has often been dubbed throughout history as a magical plant, imbibed with Sun energy.  The ancient Greeks and Romans used the plant extensively for a myriad of medicinal purposes including snake bites, menstrual cramping, GI complaints, melancholy, sciatica and wounds. Pliny the Elder wrote about the plant in his famous book on natural healing in the first century AD. The plant has also been documented for thousands of years in China’s pharmacopoeia. St. John’s Wort is often associated with fairies, witches, saints, and “servants of the Light”. It was used in exorcisms and was also stuffed into the mouth of those accused of witchcraft in order to force them to confess. In the 13th century, the Saltenitan drug list refers to it as “herba demonis fuga” or the herb that chases the devil away. It has long been used by traditional healers as a treatment for “melancholia” or what was known as “troubled spirits”.


In the American west, it is mostly considered a troublesome weed, known as Klamath Weed, or Goat Weed and has been the subject of large-scale eradication efforts. Early settlers brought it to America for its medicinal and spiritual properties and the first recorded specimen of it grown without cultivation was found in Pennsylvania in 1793. By the early to mid 1900’s, it covered more than 2.34 million acres of ranchland in northern California.  Herbicides did not halt its spread and in 1946, an Australian beetle with a voracious appetite for St. John’s Wort, Chrysolina Quadrigemina Rossi, was introduced into the Pacific northwest as a type of biological control. Within 10 years, the plant was reduced to just one percent of its previous prevalence. The beetle still complicates the potential for commercial cultivation of the plant in parts of North America.  


The plant can quickly take over recently disturbed open spaces, such as a mountainside that has been clearcut, or the freshly graded soil of an urban subdivision. While it will invade disturbed areas, it rarely invades healthy, naturalized areas. Pulling the plant up often stimulates additional growth through its runners.  It is considered a noxious weed in seven states.  It is poisonous to grazing livestock, causing behavioral changes, general restlessness, and skin irritation. 


St. John’s Wort gets its name from St. John. St. John’s Day is celebrated on the Summer Solstice, when daylight is the longest and when the plant’s flowers are in bloom.  Many consider this day the best day to harvest St. John’s Wort. Further folktales say the red spots appear on the leaves on August 29th, believed to be the anniversary of St. John’s beheading. “Wort” is an old word for “herb”. 


St. John’s Wort’s scientific name is Hypericum perforatum.  “Perforatum”, meaning “punctured,” in reference to the dots on the leaves and flower petals.  “Hypericum” means “over an apparition or picture”. Some say it translates to “over a spirit”. This is said to be in reference to the plant often being hung over religious icons to ward off evil. 


St. John’s Wort seeds can be direct-seeded in early to late Spring, or in late Summer or early Autumn.  They can also be sown indoors six to eight weeks before the expected last frost in Spring. The seeds should be surface sown and pressed into the soil but not covered. Keep the soil evenly moist, but not wet.  The seeds should germinate in 14 to 30 days.  St. John’s wort can also be cultivated by division or by softwood cuttings.


Seedlings can be transplanted when they are large enough to handle into larger pots to grow on until they are well established.  They can be transplanted into their permanent positions in late Spring or early Summer once they are two to three inches tall.  Seedlings should be planted eight to twelve inches apart.  The plants should be watered weekly throughout the first summer until they have become well established.  St. John’s Wort seeds are small and tend to grow slowly.  Keep the growing area well-weeded to eliminate weed competition.


St. John’s Wort thrives in sunny, hot, and dry conditions once it is established.  It can tolerate partial shade as well.  It will grow well in sand, clay, or rocky soil so it is not particular about soil type.  The plants can be pruned back in the Spring.


Its leaves release an unpleasant odor when they are disturbed so you may choose to not place it along a walkway or other busy area.  It spreads by seed as well as by spreading roots and will, if given the opportunity, crowd out more delicate plants, so choose your growing location carefully. You may want to consider growing it in pots. 


St. John’s Wort can be harvested in its second and subsequent years.  It is best to wait for the plants to bloom in mid-summer (usually  July) and then up to one-third of the plant may be harvested.  The medicinal properties of St. John’s Wort are at their height about mid-day, so plan to harvest then.

Seed Harvest

The fruit of St. John’s Wort consists of reddish-brown capsules that ripen around September.  Each plant produces from 15,000 to 33,000 seeds. As seeds are reaching maturity, you can snip steams of the plant to bundle together and hang inside in a warm, dry place with good airflow to complete the drying process. Seed heads can be bagged while drying to contain the seeds. 

Plant Uses

  • Medicinal
  • Xeriscaping, wildflower, or meadow gardens 

Culinary Uses

The leaves, flowers and seeds of St. John’s Wort are edible, though their culinary use seems rather limited to being added to salads or used as garnish and decorations in confectionaries. The same cautions and warnings for medicinal use apply when ingesting this plant for culinary purposes. 

Medicinal Uses

Flowers, leaves, and the flowering tips including the buds of St. John’s Wort are used in medicinal preparations.  The flowering tips tend to be the preferred part used.  The taste of the plant is slightly bitter, pungent, and sweet and the energetics are neutral or drying.  Fresh plant material is preferred for tincturing and oil making and imbue the liquids with a beautiful, thick, red color.  Dried plant material will not produce the red color and is medicinally inferior to fresh material.


For oil-making, olive oil is traditionally used for infusing St. John’s Wort. Fresh plant material is soaked in the oil and left out in the sun for several days, shaking the mixture several times a day.  The oil will become deep red in color and once strained should be stored in a cool, dark place.  While sun infusions are generally discouraged with oils, this is how it has traditionally been done with St. John’s Wort and is part of the “solar-imbued” energetics of resulting products.  It does not typically spoil when using the fresh plant material. St. John’s Wort infused oil can be applied externally on wounds, sprains, bruises, and varicose veins or be used to make salve.  The red oil was commonly referred to as “blood of Christ”. 


St. John’s Wort is often used in the treatment of stagnant depression, nerve pain, liver stagnation, cold sores and viruses.  It is said to decrease the number of herpes outbreaks a person experiences and if taken at the first sign of an outbreak, and can help to shorten the duration.  It is commonly used for shingles and other kinds of nerve pain. St. John’s Wort promotes diuresis and interestingly, is also commonly used for children experiencing bed wetting. It is considered a trophorestorative. These are herbs that provide nutrients, substances, and actions that restore or correct the weakness of a depleted organ or system. St. John’s Wort has a strong affinity for the nervous system.


In the 1898 King’s American Dispensatory, it is reported to be indicated for “spinal injuries, shocks, or concussions” among other things. In modern times, it has been popularized as a treatment for mild depression and seasonal affective disorder.  Herbalists understand that these conditions are complex and people are unique and that there is no “one” herb solution to alleviate people’s symptoms. This has not stopped the marketing of St. John’s Wort as “thee depression herb.”   While many do find it useful for such conditions, it does not work for all types of depression.  It takes several weeks of daily use before any results can be seen. From an esoteric point of view, St. John’s Wort teaches us to anchor the Spiritual Sun as a source within, rather than outside of ourselves.


There are a number of cautions to adhere to when utilizing St. John’s Wort.  While these cautions are sometimes used to give the herb a bad reputation, they also help illustrate the powerful influences the herb plays in liver health.  St. John’s Wort speeds up the CYP450 enzyme metabolism pathways in the liver. This can lead to pharmaceuticals being cleared from the liver before they have had a chance to work – this includes birth control pills, among others.   If you are taking any kind of pharmaceutical medication, it is best to avoid St. John’s Wort.  Combining St. John’s Wort with antidepressants could lead serotonin syndrome as a result of increased serotonin levels. Regular, internal use of the herb in whole-plant form can cause photosensitivity due to hypericin, one of the constituents of the plant. 


St. John’s Wort is native to Europe, west Asia, and north Africa.  It has naturalized in many parts of the world, including North America and Australia.  In the United States, it is found in most states except those with extreme Winter temperatures. 


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