Tips and Tricks for Cultivating and Nurturing St. John’s Wort

St. John’s wort, also known as goatweed or Klamath weed, is a perennial shrub with delicate yellow flowers that can thrive in various conditions, making it a popular choice among gardeners. This plant prefers full sun but can also tolerate partial sun, and it can thrive in different soil types and pH levels. It is resilient enough to survive harsh winters in USDA zone 3.

It’s important to be cautious when planting St. John’s wort, as it can be toxic to both humans and pets. This herbaceous shrub belongs to the Hypericaceae family and blooms with yellow flowers in the spring and summer. With a mature size of 1-3 feet tall and 9-24 inches wide, this plant is easy to care for and can adapt to various challenging conditions.

When nurturing St. John’s wort, make sure to provide it with ample sunlight, well-draining soil, regular watering during the establishment phase, and light fertilization in the spring. However, be cautious as this plant tends to spread quickly and can become invasive in certain regions. In fact, it is considered an invasive species in multiple states in the Pacific Northwest and the Midwest.

The image was taken by Adrienne Legault for The Spruce.

Sunlight
For optimal flower production, it’s recommended to grow St. John’s wort in full sun in the North, while in the South, a bit of shade can benefit the plant.

Soil Conditions
While St. John’s wort prefers well-drained soil, it can still thrive in slightly compacted ground. The plant is adaptable to various soil types, including acidic, neutral, or alkaline soils.

Watering
During the establishment phase, make sure to keep the perennial well-watered. Once mature, St. John’s wort shows good tolerance to drought conditions.

Feeding
To achieve the best growth, it is advisable to plant St. John’s wort in fertile soil. However, the plant can also manage in poor soil conditions. Adding compost to the soil annually can enhance its growth.

Varieties of St. John’s Wort
H. perforatum is not the only option for vibrant landscaping. The Hypericum genus offers a variety of cultivars and shrubby species, such as Hypericum x inodorum ‘Elstead’ and Hypericum x moserianum ‘Tricolor’, each with unique characteristics like red berries or variegated leaves.

Trimming
To control the spread of St. John’s wort, it is recommended to trim the plant in the early spring. Trim about one third of the plant and remove any dead branches. This is also a good time to remove any unwanted St. John’s wort plants that have grown nearby on their own.

Growing St. John’s Wort
St. John’s wort can easily propagate on its own, but if you want to propagate it yourself, you can use stem cuttings. Here’s how:
Take a clean stem cutting about 6 inches long using scissors or pruning shears.
Remove the lower leaves from the cutting.
Allow the cutting to sit for a few days to heal before planting.
Optionally, dip the cutting in rooting hormone to speed up the process.
Plant the cutting directly where you want the plant to grow.
Keep the soil moist until the cutting has rooted.

Starting St. John’s Wort From Seed
Starting St. John’s wort from seed is also simple. Follow these steps:
Lightly sprinkle the seeds over the soil and press them in lightly. Do not bury the seeds.
Spray or mist the soil and keep it moist until germination.
Once the seedlings emerge, move them outdoors or under strong grow lights.
Transplant the seedlings into their permanent locations once they are a few inches tall.

Potting and Repotting St. John’s Wort
Growing St. John’s wort in a pot can help control its spread. However, it may need to be repotted annually due to its rapid growth. The best time to repot is in early spring or early fall.
Choose a pot that is slightly larger than the current one with good drainage. Use well-draining potting soil.

Encouraging Blooms
St. John’s wort should bloom year after year with small yellow flowers and a unique scent. Here’s how to encourage more blooms:
Ensure the plant receives plenty of sunlight.
Keep the soil moist and fertilize the plant in the spring.