Great St. John's Wort is the largest and perhaps most impressive of the native St. John's Worts, standing as a bold architectural statement in the summer landscape. This robust perennial can reach heights of 2 to 5 feet, featuring large, clasping leaves and sturdy, four-angled stems. In mid-summer (July and August), it produces massive, 2-inch wide yellow blossoms that are truly spectacular, with five broad petals and a dramatic central cluster of hundreds of stamens. These showy flowers are followed by unique, pyramid-shaped seed pods that add interest well into the winter months. Native to the wet meadows and riverbanks of the upper Midwest and Northeast, it thrives in sunny, moist locations. It is a critical plant for bumblebees, who are the primary pollinators of its large, pollen-rich blooms. In the garden, it prefers full sun to partial shade and medium-wet to medium soils. Because of its size and striking appearance, it works beautifully as a focal point in a moist prairie planting or at the back of a large perennial border.

Quick facts

• Height: 2–5 ft
• Sun: Full to Partial
• Soil moisture: Medium-Wet to Medium
• Bloom time: Jul–Aug (Yellow)
• Life cycle: Perennial
• Notes: Rhizomatous
• Native range: Native to 20 states, including Iowa, Minnesota, Wisconsin, Illinois, Missouri, Nebraska

See the full growing guide and county range map for Great St. John's Wort