Hypericaceae
St. John's Wort (Hypericum perforatum)
Hypericum perforatum
An easy-care, drought-tolerant perennial once established; needs full sun for best flowering and well-drained soil, with little feeding or winter protection required.
Every 10 days
Bright indirect
° - °C
% - %
Categories
What is St. John's Wort?
St. John's Wort (Hypericum perforatum) is a easy-care plant from the Hypericaceae family. St. John's Wort is a hardy, sun-loving perennial herb native to Europe and Asia, now naturalized across temperate regions worldwide. It forms upright, multi-stemmed clumps with slender oblong leaves dotted with tiny translucent oil glands, and produces abundant star-shaped yellow flowers with black-...
St. John's Wort grows up to 90cm, spread of 60cm, watering every 10 days. It is not suitable for indoor environments and not safe for pets.
Unlike many tropical plants, St. John's Wort tolerates watering mistakes. Best for beginners. Without precautions, ingestion can cause irritation in pets. Keep out of reach of cats and dogs.
How to Care for St. John's Wort?
TLDR: St. John's Wort needs Bright indirect, watering every 10 days, and temperatures between 15-30°C with 40-70% humidity.
How Often Should You Water St. John's Wort?
Water regularly to keep soil evenly moist while young; established plants tolerate drought well and only need watering during prolonged dry spells.
How Much Light Does St. John's Wort Need?
Prefers full sun (6+ hours of direct light daily) for the most abundant blooms, though it tolerates partial shade.
What Is the Best Soil for St. John's Wort?
Adapts to sandy, loamy, clay, or chalky soils as long as drainage is good; avoid waterlogged or constantly soggy ground.
What Pot Should You Use for St. John's Wort?
Best grown directly in garden beds; if grown in a container, choose a wide, well-draining pot since the plant spreads via rhizomes.
What Is St. John's Wort and Where Does It Come From?
St. John's Wort is a hardy, sun-loving perennial herb native to Europe and Asia, now naturalized across temperate regions worldwide. It forms upright, multi-stemmed clumps with slender oblong leaves dotted with tiny translucent oil glands, and produces abundant star-shaped yellow flowers with black-dotted petal margins in early to late summer. Low-maintenance and largely pest- and disease-free, it spreads readily by seed and rhizome, making it valuable for erosion control on banks and slopes but also a listed noxious weed in some regions. It is best known as a traditional medicinal herb, though all parts contain hypericin, a compound that can cause photosensitivity in people, pets, and livestock.
How to Propagate St. John's Wort?
Clump Division
Divide every 3-4 years to keep clumps vigorous and prevent overcrowding.
- 1 In early spring or fall, dig up an established clump.
- 2 Separate the root mass into sections, each with several shoots and healthy roots.
- 3 Replant divisions immediately at the same depth in well-draining soil.
- 4 Water thoroughly after planting to help roots settle.
Materials needed:
Seed Sowing
Seeds are tiny and numerous; the plant self-seeds readily once established.
- 1 Collect ripe seed capsules in late summer.
- 2 Sow seeds on the soil surface in fall, since they need light and cold stratification to germinate.
- 3 Keep soil lightly moist until seedlings emerge in spring.
- 4 Thin seedlings once they develop several true leaves.
Materials needed:
How Big Does St. John's Wort Grow?
TLDR: St. John's Wort can reach up to 90cm tall with Fast growth rate.
Max height
90cm
Spread
60cm
Growth rate
Fast
Foliage
Deciduous
Warning: Toxic Plant
This plant can be toxic if ingested. Keep out of reach of:
Plant Uses
Medicinal
Medicinal properties
Ornamental
Great for decoration
Ground Cover
Soil coverage
Medicinal Uses
- Traditional support for mild-to-moderate depression
- Topical oil for wound healing and skin soothing
- Folk anti-inflammatory and antiviral remedy
Is your plant showing symptoms?
Click on the symptom to discover possible causes:
What Diseases Commonly Affect St. John's Wort?
TLDR: St. John's Wort is susceptible to 8 known diseases. Monitor regularly for early detection.
Rust
Rust is a common fungal disease caused by fungi in the order Pucciniales that affects a wide variety of plants. The disease gets its name from the characteristic orange, yellow, or reddish-brown pustules that appear on leaves, resembling metal rust. This obligate fungal parasite requires living plants to survive and can cause significant economic losses in agricultural crops.
Powdery Mildew
Powdery mildew is a common fungal disease caused by various fungi species including Erysiphe, Podosphaera, Oïdium, and Leveillula. It affects over 10,000 plant species worldwide. The disease thrives in warm, dry climates with high humidity and appears as a distinctive white powdery coating on plant surfaces.
Anthracnose
Anthracnose is a fungal disease caused by fungi in the genus Colletotrichum that affects many plants, including vegetables, fruits, and trees. The disease thrives in cool, wet conditions, causing dark, sunken lesions on leaves, stems, flowers, and fruits.
Verticillium Wilt
Verticillium wilt is a soil-borne fungal disease caused primarily by the fungi Verticillium dahliae and V. albo-atrum. These pathogens infect plant roots and grow within the vascular tissues, blocking water and nutrient transport, resulting in wilting and eventual plant death. The disease affects over 350 plant species including vegetables, fruits, ornamental flowers, and trees. The fungi can survive in soil for more than 10 years as resistant structures called microsclerotia.
Meaning & Symbolism
Long associated with sunlight, protection, and the summer solstice; traditionally hung over doors and windows on St. John's Eve to ward off evil spirits and misfortune.
Fun Facts
The species name "perforatum" refers to the tiny translucent oil glands dotting the leaves, which look like pinpricks when held up to light.
Its bright yellow flowers traditionally bloom around the feast of St. John the Baptist (June 24), giving the plant its common name.
It is one of the most extensively studied medicinal herbs in the world, particularly for mood support.
Despite its medicinal fame, it is classified as a noxious weed in parts of North America and Australia due to its aggressive spread.
Frequently asked questions
Is St. John's Wort toxic to pets?
How much sun does St. John's Wort need?
Is St. John's Wort invasive?
What is St. John's Wort used for medicinally?
What diseases affect St. John's Wort?
Compare with similar plants
| Attribute | Difficulty | Light | Watering | Pet Safe |
|---|---|---|---|---|
| Field Maple | Easy | Bright indirect | 14d | ✓ |
| Silver Birch | Easy | Direct sun | 14d | ✓ |
| Common Blanketflower | Easy | Direct sun | 10d | ✓ |
| Cushion Bush | Easy | Direct sun | 14d | ✓ |
Choose & Compare
Sources & References
- Hypericum perforatum - NC State Extension Gardener Plant Toolbox
- Hypericum perforatum (Perforate St. John's Wort) - Gardenia.net
- St. John's Wort - Tualatin Soil and Water Conservation District
- Hypericum (St. Johnswort)-Rust - Pacific Northwest Pest Management Handbooks
- Problems of Hypericum - Yardener.com
- A new name for an old problem-Colletotrichum cigarro is the cause of St John's wilt of Hypericum perforatum
- Erva-de-sao-joao - Wikipedia PT
- Photosensitization in Livestock - Univ. of Saskatchewan
- Hypericum perforatum: Traditional uses, clinical trials, and drug interactions
