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Overview
Gunnera manicata is the giant gunnera (Brazilian giant rhubarb), growing 72–108 inches (180–270 cm) tall and 120–192 inches (300–490 cm) wide. Individual leaf blades 36–72 inches (90–180 cm) across — among the largest leaves of any herbaceous plant cultivated in temperate gardens. The leaves are kidney-shaped to rounded, prominently veined, and coarsely toothed, supported on massively thick spiny petioles 48–96 inches (120–240 cm) covered in stout reddish prickles. Conical reddish-brown flower spikes 36–48 inches (90–120 cm) emerge at ground level between the petioles in early to midsummer, bearing thousands of tiny flowers followed by small orange-red berries. Harbors endosymbiotic Nostoc cyanobacteria in specialized glands at the stem bases — the cyanobacteria fix atmospheric nitrogen, a symbiosis unique among flowering plants. Fully deciduous — dies back to a massive crown after the first hard autumn frost. Winter crown protection is required in zones 7–8: fold the dead leaves over the crown to form an insulating mound. Requires consistently wet to boggy soil — streambanks, pond margins, and bog garden edges are the suited sites. Space allocation: 120–192 inches (300–490 cm) in all directions. Not related to rhubarb (Rheum) — the common name references the superficial leaf resemblance. Native to the coastal mountains of southern Brazil (Serra do Mar). Non-toxic — the leaf petioles have been consumed as a cooked vegetable. Deer-resistant. Zones 7–10. Growth rate is fast in adequate moisture.
Native Range
Native to the coastal mountains of southern Brazil, primarily the Serra do Mar in Santa Catarina and Rio Grande do Sul, growing in humid forest margins, streambanks, and clearings at moderate elevations.Suggested Uses
Grown as a specimen at pond, stream, or bog garden edges in zones 7–10. Requires consistently wet soil and 120–192 inches (300–490 cm) of space. Companion to Rodgersia, Ligularia, and Lysichiton americanus at water features. Not suited to small gardens. Non-toxic. Deer-resistant.How to Identify
Appearance
Size & Dimensions
Height6' - 9'
Width/Spread10' - 16'
Reaches mature size in approximately 5 years
Bloom Information
Early to midsummer (June–July). Conical reddish-brown flower spikes 36–48 inches (90–120 cm) at ground level among the petioles. Small orange-red berries follow. The massive foliage — not the flowers — is the primary feature, reaching full size in mid to late summer.Detailed Descriptions
Flower Description
Reddish-brown conical flower spikes 36-48 inches (90-120 cm) at ground levelFoliage Description
Dark green, kidney-shaped to rounded, prominently veined, coarsely toothed, 36-72 inches (90-180 cm) acrossGrowing Conditions
Sun Requirements
Requires 4-8 hours of direct sunlight daily
• Full Sun: 6+ hours of direct sunlight
• Partial Shade: 3-6 hours of direct sunlight
• Full Shade: Less than 3 hours of direct sunlight
Care & Maintenance
Care Guide
Part sun to full sun with consistent moisture. Consistently wet to boggy soil required — streambanks, pond edges, bog gardens. Space 120–192 inches (300–490 cm). Winter crown protection in zones 7–8: fold dead leaves over crown after first frost. Apply compost mulch in autumn. Fertilize in spring. Non-toxic. Deer-resistant. Zones 7–10.Pruning
After the first hard autumn frost kills the leaves, cut petioles partially and fold or pile them over the crown for winter insulation. Remove the protective mound in early spring before new growth. Cut all remaining dead material to the ground. Remove flower spikes at the base if self-seeding is not desired.Pruning Schedule
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fallearly spring