The creeping St. John’s wort (Hypericum calycinum) is a low, creeping, woody shrub commonly found on steep European slopes. The common name has roots in biblical texts, but has historically been applied to several different species; this particular species is likely not the same as the creeping St. John’s wort mentioned in the bible.
I. Appearance and Characteristics
Hypericum calycinum is a species of prostrate or low-growing shrub in the flowering plant family Hypericaceae. Widely cultivated for its large yellow flowers, its names as a garden plant include Rose-of-Sharon in Britain and Australia, and Aaron’s beard, great St-John’s wort, creeping St. John’s wort and Jerusalem star. Grown in Mediterranean climates, widely spread in the Strandzha Mountains along the Bulgarian and Turkish Black Sea coast.
In North America the name Rose of Sharon is applied to a species in a different order, Hibiscus syriacus.
The common name of St. John’s wort, which is used to describe plants of the entire genus, arose from the old tradition of Hypericum plants being burned on the eve of St. John’s Day, to stave off evil spirits. The species name, calycinum, comes from the flower’s prominent calyx, the whorl of the sepals.
Hypericum calycinum is a low, creeping, evergreen woody shrub (classified as a subshrub or shrublet) to about 1 m tall and 1–2 m wide but often smaller. The green, ovate leaves grow in opposite pairs. Usually 4 inches long, the undersides of the leaves are net-veined. In the sun, the leaves are a vibrant green color, and in shade, the leaves are a lighter yellow-green. The underside of the leaves is a blue-green color and in the fall, the leaves take on a purple color.
The flowers are 3–5 cm in diameter, a rich yellow, with five petals and numerous yellow stamens. Its flowers can be described as “rose-like” and tend to be single or in units of two or three, flowering in June to September.
Hypericum calycinum is indigenous to southeast Europe and southwest Asia. It is a popular, semi-evergreen garden shrub with many named cultivars and hybrids derived from it.
Although the genus is generally not affected by rust fungi, it can appear on H. calycinum (and another cultivated plant, Hypericum × inodorum ‘Elstead’).
II. How to Grow and Care
Sunlight
Creeping St. John’s wort needs sufficient sunlight but doesn’t tolerate direct light. Grow the plant in the shade of other plants or on a balcony away from strong, hard light. Expose it to more sunlight in the spring and fall to help it grow, but in the summer, place the potted plants in half-shaded places and mist them with water to cool the temperature and increase humidity. Otherwise, symptoms like drying leaf tips may appear.
Temperature
plants of the Hypericum genus are widely distributed. They like warm, moist environments; the best temperature range for the plants is 20 to 26 ℃, but they can tolerate temperatures as low as -10 ℃. They require little water and endures drought, but don’t tolerate waterlogged soil. Avoid watering so frequently that the soil gets waterlogged.
Watering
Creeping St. John’s wort can withstand drought but is intolerant of waterlogged soil. In the first year after planting, about 2.5 cm of water every week will be enough. In areas with plentiful rain, no additional watering is needed. From the second year on, creeping St. John’s wort doesn’t need any additional watering, as normal precipitation will meet its needs for water. If over-watered, its roots are likely to rot due to waterlogging, and leaves will wither and dry up.
Soil
Creeping St. John’s wort can adapt to a wide range of soil types. It grows well in most common soils (except for heavy clay) and prefers sandy loam with good drainage. A slightly acidic loam with a 5.5-7.0 pH value is ideal. Creeping St. John’s wort is tolerant of barren soil and drought, but if the soil can’t drain water well, waterlogging can cause the roots to rot.
Fertilizing
Creeping St. John’s wort requires very little fertilizing. Usually, no additional fertilization is needed after the initial planting, unless obvious symptoms of slow growth appear. If that happens, apply some low-concentration balanced compound fertilizer (10-10-10 NPK ratio).
Planting Instructions
plant creeping St. John’s wort in the early spring or early fall. Choose a cool, shaded place, such as within tree shade. Remember to clear the soil first and remove weeds. Dig a planting pit slightly shorter than the diameter of the root ball and 3 times wider. If you’re planting more than one sapling, avoid planting them too close, or low light and poor ventilation may result in powdery mildew. Pile some soil around the root collar (the juncture of trunk and roots) to form a gentle slope, and this helps disperse water. After planting, press the soil firmly and water thoroughly. Note the distance between each.
Some plants in the Hypericum genus have subterraneous rhizomes that tend to expand in all directions. To prevent excessive expansion, it’s a good idea to fence the planting spots or set brick perimeters around them to control their growth.
Pruning
Creeping St. John’s wort doesn’t need much pruning. To promote more lush growth, trim 1/5-1/4 of the total branch length by the end of spring or early summer, which promotes new branches to sprout. Creeping St. John’s wort buds and leaves both grow in pairs. Generally speaking, cutting one branch off promotes the pair of buds beneath the incision to develop into two branches.
For creeping St. John’s wort with robust growth and branches crossing inward, winter is the time for an overall pruning. As perennial herbaceous plants, you may just clip them flat with a sickle and they will revive. Creeping St. John’s wort has a short life span, so you can also consider getting new seedlings to replace the old ones once they start to decline.
Propagation
Creeping St. John’s wort can be propagated by seeding, cuttage, or plant division. To sow seeds yourself, sow them in a sand bed. Dust a thin layer of soil on them, water once, and sprout the seeds in temperatures of 10 to 12 ℃. Keep the potting soil moist. Transplant seedlings when they grow to 5 to 10 cm tall.
For St. John’s worts with dense branches, propagation is usually performed at the end of summer by soft-branch cuttage. Choose some robust, soft branches that sprouted in the current year. Cut 10 to 15 cm-long from the tip, making sure to keep at least 2 full leaves on each branch. Insert the cut branches into the soil and keep half the length aboveground. Keep the soil and the environment moist. When the seedlings reach 20 cm tall, transplant to pots. Seedlings need to grow to 70 cm tall to move outdoors or wait until the end of the next summer.
Transplanting
The most suitable period for relocating creeping St. John’s wort is during S1-S3, largely because these seasons provide optimal weather and soil conditions for the plant’s growth. When transplanting, remember to select a location with full sun or partial shade. Ensure the site has well-drained soil, as creeping St. John’s wort dislikes waterlogged conditions. Last but not least, make every effort to minimize root disturbance.
III. Uses and Benefits
- Ornamental uses
Creeping St. John’s wort is a showy garden ornamental, featuring large flowers that nearly cover the foliage underneath. This plant is a great ground cover and will easily spread over hillsides and slips while stabilizing soils. It will also do well in rock gardens, border fronts, or as decorative cover under tree canopies.
- Medicinal uses
Various species of the genus Hypericum have been used since ancient times as herbal remedies. This species has been used traditionally to reduce muscle spasms and for the treatment of asthma.
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