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Plant library  ·  Shrubs

St. John's Wort (Shrub)

Hypericum prolificum

Shrubby St. John’s wort is a compact native perennial shrub that brings bright yellow flowers from early through late summer. At about 3 feet tall and 3 feet wide, it forms a useful middle layer in a sunny planting, filling space without becoming a large screen. Its drought tolerance and deer resistance suit low-input borders, banks, and naturalistic beds within USDA Zones 4 through 8.

Sunlight Full Sun
Water Moderate
USDA zones 4–8
Planning spacing 3 ft
Typical mature size 3 ft tall, 3 ft wide
Typical bloom Early summer - late summer

St. John's Wort (Shrub) spacing and mature footprint

Space St. John's Wort 3 ft apart, measured center to center (90 cm).

The mature spread is about 3 ft (90 cm), so neighboring plants just meet at maturity without crowding.

Treat 3 ft as a planning baseline — cultivar and local growing conditions shift the final footprint.

Compare with the full shrub and hedge spacing chart

Three plants set 3 ft apart, center to center; shaded circles show the 3 ft mature spread.

Placement and use

Use this shrub at the front or middle of a mixed border, leaving taller shrubs and perennials behind it so the summer flowers remain visible. A repeated row can make a low informal edge along a drive, open lawn, or wide path; keep the planting bed deep enough that its rounded form does not spill into circulation space. It also works in grouped native plantings and on slopes or banks where a compact woody layer is useful.[1][2]

Spacing and mature footprint

Plant on 3-foot centers for a continuous, shoulder-to-shoulder grouping at maturity. Its mature width is also about 3 feet, so this spacing leaves little open ground between established plants; pull centers farther apart if you want distinct mounds or room for lower perennials between them. Set the front row back from paths by at least half its width, about 18 inches, to preserve clear passage.

Sun, water, and soil

Give it full sun for the strongest flowering display, with moderate water while it establishes. It tolerates poor, dry soil and drought, making it a practical choice for sunny sites that are not irrigated regularly. Avoid placing it in a tight, heavily shaded bed where nearby shrubs will crowd its compact form and reduce its light.

Seasonal notes

The bright yellow flowers occupy the shrub from early summer into late summer, so use it where a long summer accent is wanted after spring bloomers fade. Flowers are produced on new growth; an early-spring pruning window allows the plant to be tidied before the new season begins. Seed capsules can remain into winter, adding off-season structure to a border.[1][2]

Growing facts

Botanical name
Hypericum prolificum
Type
Shrub
Category
Shrubs
Lifecycle
perennial
USDA hardiness zones
4–8
Sunlight
Full Sun
Water
Moderate
Planning spacing
3 ft
Typical mature size
3 ft tall, 3 ft wide
Typical bloom season
Early summer - late summer
Plan a garden with st. john's wort

References

  1. Common St. John’s Wort — Hypericum prolificum — North Carolina Extension Gardener Plant Toolbox
  2. Hypericum prolificum — Plant Finder — Missouri Botanical Garden