How to Grow Giant Gunnera
Wikimedia Commons
Giant Gunnera
Gunnera manicata
herbaceous perennialGunnera manicata is a colossal herbaceous perennial native to South America, renowned for producing the largest leaves of any non-woody plant—reaching up to 10 feet across on petioles that can exceed 5 feet. Its dramatic architectural foliage creates a prehistoric, tropical aesthetic in temperate gardens. Small reddish flowers appear in dense cone-like inflorescences at the plant's base during late spring and early summer.
When should you plant Giant Gunnera in your zone?
Get a personalized planting timeline — when to start seeds, transplant, and harvest — based on your USDA zone and local frost dates. Free to start.
Example Giant Gunnera timeline · Pittsburgh, PA (Zone 6b)
-
Plant Giant Gunnera
Around Apr 17Near Pittsburgh's average last spring frost.
-
Tend & protect
Late spring–summerWatering, feeding, and pest-watch reminders.
-
Harvest Giant Gunnera
Late summer into fallBefore the first fall frost (≈ Nov 8)
Sample dates for Pittsburgh, PA. Sign up to get exact Giant Gunnera dates for your own zip code.
Growing Conditions
Soil
Growing Zones
Find your zone →Thrives in zones 7b-10, with protection needed in zone 7 and colder regions
Sign up free to see if Giant Gunnera grows in your zone — and get a personalized planting timeline.
Get my Giant Gunnera timeline →Growth Stages
Establishment
Year 1Young plant with small, hand-sized leaves emerging from rhizome; growth is slow in first season
Keep consistently moist and protect from wind and direct sun. Mulch heavily to retain moisture and regulate temperature. Avoid transplanting once established
Vegetative Development
Years 2-3Leaves gradually increase in size year by year; petioles and leaf blades expand significantly. Plant establishes deeper, more extensive root system
Maintain consistent moisture and rich soil fertility. Remove any damaged leaves promptly. Apply balanced fertilizer in spring and early summer. Protect from strong winds that damage large leaves
Rapid Growth
Years 4+Mature leaves reach 6-10 feet across on massive petioles. Plant becomes true architectural focal point with dramatic presence
Provide abundant moisture and nutrients. Feed monthly with high-potassium fertilizer during growing season. Use stakes or supports if needed in windy locations. Remove damaged foliage
Flowering
4-6 weeks (late May-June in Northern Hemisphere)Dense, cone-shaped flower spikes emerge near plant base in late spring/early summer; flowers are small and reddish, not showy but botanically interesting
Maintain consistent moisture during flowering. Deadheading not necessary as flowers are not prominent. Seeds rarely form viable seed in cooler climates
Dormancy
November-March (4-5 months)Foliage dies back completely in autumn after frost; entire above-ground growth disappears, leaving only dormant rhizome underground
Cut back dead foliage in late autumn. Apply heavy mulch (6-12 inches of compost, straw, or leaf matter) over crown for winter protection, especially in zones 7-8. Reduce watering significantly
Companion Planting
Plan your garden →Plant with:
Avoid planting near:
Common Pests
-
and
Hand-pick early morning or evening; use copper barriers; apply iron phosphate-based baits; encourage natural predators like ground beetles and toads
-
Increase humidity with misting; use neem oil spray; strong water spray to dislodge; insecticidal soap if severe
-
Remove by hand with isopropyl alcohol on cotton swab; spray with insecticidal soap; apply neem oil; improve air circulation
-
Ensure excellent drainage and avoid waterlogging; remove affected portions of rhizome and repot in fresh soil; improve air circulation; apply fungicide if systemic infection suspected
Uses
Architectural Focal Point & Dramatic Garden Feature
HouseholdGunnera manicata serves as a living sculpture and bold statement plant in moisture-rich gardens, creating dramatic tropical ambiance in temperate climates. Its massive leaves provide immediate architectural interest and can anchor water garden designs, large borders, or specimen plantings. [source]
Wildlife Shelter & Habitat Provider
WildlifeThe expansive leaf canopy and dense foliage structure provide shelter and habitat for beneficial insects, amphibians, and small wildlife. The moist growing conditions attract frogs, toads, and ground-dwelling creatures essential for garden ecosystem health. [source]
Artistic & Botanical Reference
CraftGunnera manicata is studied by botanists and horticulturists for its record-breaking leaf size and unusual morphology. Artists and garden designers reference it as inspiration for monumental botanical forms and tropical garden aesthetics. [source]
Water Feature Integration
HouseholdExcellent choice for poolside, stream-edge, or bog garden placement where its need for consistent moisture aligns perfectly with water-saturated growing conditions. Creates immersive water garden displays when positioned near ponds or streams. [source]
Harvest Tips
Gunnera manicata is not harvested for food or material. It is grown exclusively as an ornamental specimen plant. Individual leaves do not require harvesting; simply remove damaged or dead foliage throughout the season. Cut back all growth in late autumn after frost kills foliage completely, leaving the dormant rhizome undisturbed
Fun Facts
- 🌱 Gunnera manicata produces some of the largest leaves of any non-woody plant on Earth, with individual leaves capable of exceeding 10 feet in diameter and petioles reaching 5-6 feet in length—creating an area large enough to shelter a person from rain
- 🌱 The plant's dramatic size and prehistoric appearance made it a favorite of Victorian gardeners in England and continues to evoke a Jurassic landscape aesthetic in modern gardens despite its South American origins
- 🌱 Gunnera forms a symbiotic relationship with cyanobacteria (Nostoc) housed in specialized cavities at the base of petioles, allowing the plant to fix atmospheric nitrogen and reduce its fertilizer requirements
Gardening Terms
New to gardening? Learn about terms used in this guide:
Join 30,000 gardeners planning their gardens with LizPlants.
Get your personalized Giant Gunnera planting timeline
Tell us your zip code and we'll calculate exactly when to start Giant Gunnera seeds, transplant seedlings, and harvest — based on your USDA zone and local frost dates. Includes calendar reminders and printable task lists. Free to start.
Get my Giant Gunnera timeline →