Atlantic St. John's wort (Hypericum tenuifolium)

Also known as: Narrowleaf St. John's Wort

Atlantic St. John's Wort (Hypericum tenuifolium) is notable for its fine, linear leaves and abundant bright yellow blooms. These flowers typically herald the arrival of summer in their native habitats, thriving best with plenty of sunlight.

**Distinguishing Characteristics:**
1. **Flowers:** Vibrant yellow with five petals, blooming from late spring to summer.
2. **Leaves:** Narrow, linear, and opposite, giving the plant a delicate look.
3. **Height:** Typically grows between 1-3 feet tall.
4. **Stems:** Reddish and slender, adding to its distinctive appearance.

**Ideal Growing Conditions:**
1. **Light:** Prefers full sun to partial shade.
2. **Soil:** Does well in sandy, well-drained soils, often found in coastal plains.
3. **Water:** Drought-tolerant once established, requiring minimal watering.
4. **Hardiness:** Best suited for USDA zones 6-9.

Due to its compact growth habit, Atlantic St. John's Wort is ideal for ornamental borders and rock gardens, making it a versatile choice for challenging environments.

In This Article

Care Tips Water Sunlight Temperature Soil Fertilize Prune Propagation Repotting Toxicity

Attributes of Atlantic St. John's wort

Lifespan

Perennial

Plant Height

30 cm to 61 cm

Spread

30 cm to 60 cm

Leaf Color

Green

Flower Size

1-2 cm

Flower Color

Yellow

Images of Atlantic St. John's wort

Quickly Identify Atlantic St. John's wort

Petite mat-forming shrub, 4–20 inches (10–50 cm) high.

Bright-yellow flowers with numerous stamens creating a halo effect.

Narrow leaves, 0.5-1 inch (1.3-2.5 cm) long, opposite arrangement.

Fruit capsules with 2-5 cells, varying green to brown, dry texture.

Distinct 2-edged stem, newer growth with 2-4 ridges transitioning to smoother rounded texture.

Scientific Classification of Atlantic St. John's wort

Phylum

Vascular plants

Class

Dicotyledons

Order

Malpighiales

Family

St. John's wort

Genus

St. John's worts

Species

Atlantic St. John's wort

Planting and Growing of Atlantic St. John's wort

Care Difficulty

Moderate

Watering Schedule

Every 4 days

Sunlight Requirements

Full sun

Sunshine Duration

4-6 hours

Ideal Temperature

60-75℉

Soil Type

Potting Mix, Peat Mix

Soil pH

6.5-7.5

Fertilizer Type

Balanced

Pruning Season

Spring, Summer

Pruning Area

Branches, Leaves

Pruning Frequency

2 times a year

Repotting Season

Spring

Pot Type

Plastic, Ceramic

How to Water Atlantic St. John's wort?

For Hypericum tenuifolium, the watering amount is crucial to ensure the soil is adequately moist yet not oversaturated. The rule of thumb is to water until about 250ml per session so that moisture can reach deep roots without water pooling at the top or bottom of the pot.

What are the symptoms of an underwatered Atlantic St. John's wort? ›

What should I do if my Atlantic St. John's wort is not getting enough water? ›

What are the symptoms of an overwatered Atlantic St. John's wort? ›

How to save an overwatered Atlantic St. John's wort? ›

What Are the Sunlight Requirements for Atlantic St. John's wort?

Sunlight Requirements: Full sun, Partial sun

Duration of light: 6 to 8 hours daily

Hypericum tenuifolium thrives best with a mix of full sun and partial sun, particularly benefiting from about 6 to 8 hours of sunlight daily. Proper lighting boosts its blooming capacity, enhances foliage vibrancy, and supports a resilient structure.

What is the ideal light setup for Hypericum tenuifolium? ›

How can you achieve these lighting conditions? ›

What benefits does ideal lighting provide? ›

What Is the Ideal Temperature Range for Atlantic St. John's wort?

Ideal Temperature: 60 ~ 75℉

Hypericum tenuifolium thrives in temperatures ranging from 60 to 75 degrees Fahrenheit. This range facilitates proper metabolic functions and encourages healthy growth and blooming. Maintaining this temperature helps the plant to efficiently photosynthesize and access the nutrients it requires for survival and development.

What Soil is Best for Atlantic St. John's wort?

Soil type: Sandy loam, Loam, Sandy soil

Soil PH: 6.5 ~ 7.5

Hypericum tenuifolium thrives in well-drained soil. Ensuring good drainage prevents root rot and allows the roots to access the necessary oxygen. It mimics the plant's natural habitat, fostering robust growth and vibrant blooms. This plant prefers soils with modest nutrient levels. Excessive nutrients can lead to lush foliage at the expense of flowers. A balanced nutrient supply supports healthy growth and abundant flowering. While Hypericum tenuifolium is drought-tolerant, it performs best in soil that retains some moisture. Consistent moisture availability is crucial for maintaining the plant's health and promoting steady growth.

How to Fertilize Atlantic St. John's wort?

Fertilizer type: Balanced

For Hypericum tenuifolium, provide a balanced, water-soluble fertilizer mixed at half the recommended dose to avoid nutrient burns. This ensures the plant receives adequate nutrition without overwhelming it with excessive nutrients.

How to Prune Atlantic St. John's wort?

Pruning Time: Spring, Summer

Begin by inspecting the plant, identifying any dead, diseased, or crossing branches that need removal. Look for branches that may be impeding airflow and light penetration. Trim the plant to maintain its natural shape and encourage a denser growth pattern. Make cuts at a slight angle just above a leaf node to promote new growth. To prevent the spread of disease, sanitize your pruning tools with a standard disinfectant between each cut, especially if you are cutting diseased branches. After pruning, monitor the plant for any signs of stress or disease. Water the plant thoroughly and consider applying a light layer of mulch to retain moisture. More About Pruning Techniques→

How to Propagate Atlantic St. John's wort plant?

Propagate Time: Early spring,Late spring,Early summer

Begin by sowing the seeds in seed trays filled with a well-draining, sandy soil mix. Lightly cover the seeds with soil and water gently. Place the trays in a warm, sunny location to encourage germination.

Select healthy, non-flowering stems and use sharp pruners to cut a 4-6 inch piece. Remove the leaves from the lower half and dip the cut end in rooting hormone. Plant the cutting in a pot filled with moist, well-draining soil.

Carefully dig up the established plant in spring. Using a sharp tool, divide the root ball into sections ensuring each has roots and shoots. Replant the divisions at the same depth as the original plant and water thoroughly.

More About Propagating Techniques→

How to Repot Atlantic St. John's wort plant?

Repotting frequency: Every two years

Look for signals such as stunted growth, roots emerging from drainage holes, or the soil drying out very quickly. These could indicate the need for repotting. Ideally, repotting should be carried out in the early spring or late autumn when the plant is not actively flowering. This avoids stressing it further in peak growth periods.

Select a pot that is one to two inches larger in diameter than the current one. Make sure it has adequate drainage holes. This size allows for root expansion without overwhelming the plant with too much soil, which can lead to waterlogging. The material can be terracotta, which allows better airflow to the roots.

Opt for a well-draining sandy mix, offering a balance of organic matter and sand. This helps prevent waterlogging yet retains enough moisture for the roots to absorb nutrients effectively. The soil should mimic the plant's natural environment as much as possible for optimal growth.

Toxicity

Ingestion

WARNING

The judgment on toxicity and danger is for reference only. We DO NOT GUARANTEE any accuracy of such judgment. Therefore, you SHALL NOT rely on such judgment. It is IMPORTANT TO SEEK PROFESSIONAL ADVICE in advance when necessary.