How to Grow Hypericum Perforatum

Small stalk of St. John's wort.

Hypericum perforatum, commonly known as St. John's wort, is a beautiful and useful addition to any herb garden. Though you should take care when using any herb, you can harvest St. John's wort for many medicinal uses or use the flowers and seed pods for dye. The bright yellow flowers also make a sunny backdrop to any garden or flower bed. With a little bit of care, it is also easy to grow in most temperate environments worldwide.

Things You'll Need

• Hypericum perforatum (St. John's wort) seeds Potting soil Perlite Seed or plug trays Place to keep trays indoors Place to harden off seedlings outside Prepared ground or container

Instructions

1. Plant Seeds into Trays
   Plant the very small seeds into seed or plug trays filled with potting soil, and cover with perlite to absorb excess moisture. Plant hypericum perforatum in early spring and expect germination in 10 to 20 days.

2. Harden Seedlings
   Once seedlings are well-established in the seed trays, set the trays outside for a brief period each day to harden the St. John's wort before planting.

3. Prepare Ground or Container
   Prepare an open area of semi-dry soil in sun or light shade. If you plan to grow hypericum perforatum in containers, fill large containers with a mix of potting soil and organic compost.

4. Plant the Seedlings
   Plant the St. John's wort seedlings outside after all danger of frost has passed. Set out about 12 inches apart unless planting into a container. For container planting, place the plants in large clumps to offset the three-foot height.

5. Use Basic Maintenance
   Water the hypericum perforatum during the summer months if there isn't sufficient rainfall, keeping the ground semi-moist but not wet. Use liquid fertilizer only twice during the growing season; more than that will cause the plant to produce more leaves than flowers.

6. Cut Back After Flowering
   Cut the St. John's wort back after flowering to prevent self-seeding.

7. Divide Clumps
   Divide established clumps in the autumn to prevent the plants from becoming root-bound.

8. Ignore Through Winter
   Leave the hypericum perforatum alone through the winter. The plants are winter hardy in most temperate zones.

Tips & Warnings

• Hypericum perforatum is generally hardy in temperate and subtropical areas of all continents except Antarctica. St. John's wort thrives in areas with either a winter or summer dominant rainfall pattern, but high altitudes or temperatures too low for germination or seedling survival restrict its distribution. Hypericum perforatum seeds can survive for decades and then germinate under the right conditions. St. John's wort will generally be in full flower around June 24 (St. John's Day).

• Because of its ability to adapt to its environment, St. John's wort acts as both a toxic and invasive weed and is listed as a noxious weed in more than 20 countries worldwide. Hypericum perforatum is poisonous to livestock when ingested and can cause sensitivity to light, central nervous system suppression, spontaneous abortion and death. Although St. John's wort has many traditional and valid pharmaceutical uses, it has been rated unsafe for internal use by the U.S. Food and Drug Administration.