Giant rhubarb (Gunnera manicata) is one of the largest herbaceous perennials on earth, native to southern Brazil and Colombia. This tropical giant reaches 6 to 10 feet tall and spreads 8 to 14 feet wide, with leaves that can stretch 6 to 8 feet across, so enormous they dwarf most garden plants and create an instantly dramatic focal point. Hardy in zones 7 through 10, it thrives in consistently moist, fertile, humus-rich soils in partial shade, making it a showstopping choice for gardeners with space, patience, and boggy ground to work with.
120
Partial Shade
Moderate
7-10
120in H x 168in W
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Moderate
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Giant rhubarb's puckered, deeply lobed leaves emerge on stiff, prickly, reddish-hairy stalks, creating a prehistoric silhouette that commands attention. Flowers appear in summer as showy spikes, followed by equally striking fruit displays. This perennial demands consistently moist to boggy soil and partial shade to thrive; in full sun or dry conditions, leaves become stressed and performance suffers. The plant is intolerant of extreme heat or cold and rarely succeeds in hot or dry climates, so site selection is everything. Once established in the right spot, however, it becomes a living sculpture that grows larger and more impressive each season.
Giant rhubarb shines in rain gardens and wetland-edge plantings where its massive foliage anchors the landscape and its tolerance for consistently wet soils prevents stress. Its architectural leaves create dramatic living screens or backdrops in large borders. The showy summer flowers and ornamental fruit add seasonal interest beyond the foliage display.
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Remove dead or damaged leaves as they appear to keep the plant looking healthy and prevent disease entry points.
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“Gunnera manicata hails from the cloud forests and wetlands of southern Brazil and Colombia, where it evolved to become one of the world's largest herbaceous plants. Its journey into Western gardens began in the Victorian era, when botanists and collectors brought seeds and specimens back from South America. The common name 'giant rhubarb' reflects early confusion with true rhubarb (Rheum species), though these plants belong to entirely different families. Over decades, this Amazonian giant captured the imagination of gardeners seeking drama and scale, particularly in temperate zones where it could survive winters in sheltered locations.”