How to Grow Hypericum
Also known as St. John's Wort, Hypericum is a hardy perennial that produces shrubby, oval-shaped green foliage. The mature plant grows to 3 to 6 feet in height, bearing golden flowers that bloom in midsummer. Hypericum yields a reddish-brown fruit that releases several small seeds when it ripens in September.
Hypericum grows prolifically from seed sowed in sunny, well-drained soil within USDA hardiness zones 4 through 8.
Test the soil using a soil testing kit purchased from a garden centre prior to sowing the seed in the early spring, once the threat of frost has passed. Hypericum prefers a soil pH between 5.5 and 7.
Loosen the soil with a pitchfork and amend if necessary. Add lime to the soil for a pH below 5.5 or peat moss for a pH above 7.0. Add the required amendment per label instructions.
Broadcast the seeds over the soil. Simply grab a handful of seeds and fan them out on the soil in front of you. Use a garden rake to cover the sowed seed with a light layer of soil.
Dampen the soil with a light misting of water from your garden hose. Keep the soil moist, not wet during germination, which varies widely between three weeks and three months. Continue to maintain moist soil to a 1-inch depth, watering once per week as the Hypericum seedlings grow.
Weed out the weakest Hypericum seedlings when they develop their second set of leaves. Remove weeds between plants frequently, providing the Hypericum with a spacing of 15 inches between plants.
Feed the Hypericum a diet of all-purpose fertiliser, applied according to manufacturer's instructions. Hypericum appreciates monthly feedings.
- A 3- to 4-inch layer of bark mulch, applied in the late fall, will keep the Hypericum warm throughout the winter. Allow the layer of mulch to remain in the spring and summer to promote drainage and reduce weed growth.
- Do not overwater the seeds or Hypericum plants. Overwatering promotes rotting. If the soil feels moist to a depth of 1 inch, do not add more water.