Kalm's St. John's Wort is a small, dense, evergreen shrub native to the Great Lakes region, where it thrives in rocky and sandy soils from dry woodlands to moist lakeshores. This hardy species grows as a compact mound to 2, 3 feet tall with distinctive narrow, bluish-green leaves arranged on striking 4-angled stems. Bright yellow flowers bloom from July through August, followed by showy fruit that extends the season's interest. Hardy in zones 4, 7, it tolerates everything from poor soils to established drought once established, while remaining virtually pest and disease-free.
Partial Sun
Moderate
4-7
36in H x 36in W
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Moderate
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The 4-angled stems and narrow, paired bluish-green leaves give this shrub a delicate, almost architectural quality that sets it apart from other garden plants. Its genuine evergreen character (though some leaves may drop in cold winters) provides year-round structure, while the prolific summer blooms and decorative fruit keep it visually engaging long after flowers fade. Thriving equally well in full sun or partial shade, and tolerating poor, dry soils once rooted, this is a shrub that asks very little but gives consistent, reliable beauty.
Kalm's St. John's Wort is grown as an ornamental shrub, particularly valued as a hedge plant where its dense, upright branching and compact size create attractive structure. Its evergreen foliage, showy summer blooms, and decorative fruit make it a four-season landscape asset in northern and cooler temperate gardens.
No timeline data available yet for this variety.
Prune after bloom in late summer if needed to maintain dense form and encourage bushier growth. The upright branching habit naturally creates a neat mound, so pruning is optional unless you want to refine shape or control size.
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“Kalm's St. John's Wort carries the name of Pehr Kalm, an 18th-century Swedish botanist and student of Carl Linnaeus who explored North America and documented its native plants. The species is endemic to the Great Lakes region of the United States, where it evolved in the rocky and sandy habitats surrounding the lakes. This native shrub represents generations of adaptation to a specific ecosystem, and its rediscovery in cultivation honors both Kalm's botanical legacy and the regional landscapes where it naturally occurs.”