Giant Rhubarb: The Prehistoric Garden Giant That’s Not Actually Rhubarb
If you’ve ever dreamed of creating a garden that looks like it belongs in the age of dinosaurs, giant rhubarb (Gunnera manicata) might just be your ticket to prehistoric paradise. Despite its common name, this dramatic plant isn’t related to the rhubarb you might grow for pie – it’s actually a South American native that’s become a favorite among gardeners who want to make a serious statement in their landscape.
What Makes Giant Rhubarb So Special?
Giant rhubarb is all about drama and scale. This architectural marvel produces leaves that can grow an astounding 6 to 10 feet across – yes, you read that right! These massive, umbrella-like leaves create an almost tropical, primordial atmosphere that’s hard to achieve with any other plant. The leaves are deeply lobed and textured, supported by thick, sturdy stems that can reach impressive heights of 8 to 12 feet.
During summer, the plant produces tall, cone-shaped flower spikes that can tower even higher than the foliage, though most gardeners grow this beauty primarily for its spectacular leaves rather than its blooms.
Where Does Giant Rhubarb Come From?
Gunnera manicata hails from the mountains of southern Chile and western Argentina, where it thrives in cool, moist conditions. In its native habitat, it grows along stream banks and in boggy areas where water is abundant year-round.
Is Giant Rhubarb Right for Your Garden?
Before you get swept away by visions of your own Jurassic garden, there are some important considerations. Since giant rhubarb isn’t native to North America, you’ll want to think carefully about whether it’s the best choice for your space.
Consider giant rhubarb if you:
- Have a large garden with space for a dramatic focal point
- Can provide consistently moist to wet soil conditions
- Live in USDA hardiness zones 7-10
- Want to create a bold, architectural statement
- Have protection from strong winds
Skip giant rhubarb if you:
- Have limited garden space
- Struggle with dry soil conditions
- Live in zones colder than zone 7 without protection
- Prefer low-maintenance plants
Native Alternatives to Consider
While giant rhubarb is undeniably stunning, consider these native alternatives that can provide similar dramatic impact while supporting local ecosystems:
- Wild ginger species – For large, heart-shaped leaves in shaded areas
- Umbrella plant (Peltiphyllum peltatum) – Native to the Pacific Coast with large, round leaves
- Large-leaved aster species – For bold foliage in wetland gardens
- Native sedges and rushes – For water garden impact with local benefits
Growing Giant Rhubarb Successfully
If you decide giant rhubarb is perfect for your garden vision, here’s how to keep it happy:
Location and Growing Conditions
Giant rhubarb is essentially a giant water baby. It thrives in consistently moist to wet soil and actually performs best in boggy conditions. Choose a spot with partial shade – while it can tolerate some sun, too much direct sunlight combined with insufficient moisture will leave you with crispy, sad leaves.
The soil should be rich in organic matter, so work in plenty of compost before planting. Good drainage isn’t as critical as it is for most plants, since giant rhubarb actually appreciates wet feet.
Planting and Care Tips
- Water generously: This plant drinks like it’s preparing for a desert crossing. Never let the soil dry out completely
- Provide wind protection: Those massive leaves are like natural sails – strong winds can shred them or topple the entire plant
- Feed regularly: Use a balanced fertilizer monthly during the growing season to support all that impressive growth
- Mulch heavily: A thick layer of organic mulch helps retain moisture and keeps roots cool
- Plan for winter: In zones 7-8, protect the crown with mulch or the actual leaves (cut but left in place) during winter
Seasonal Care
Giant rhubarb is deciduous, so don’t panic when it dies back in fall – this is completely normal. Cut the plant back to ground level after the first frost, or in milder climates, leave the old leaves to protect the crown and remove them in early spring before new growth begins.
Spring emergence is quite the show – new leaves unfurl like massive umbrellas opening, and growth can be surprisingly rapid once temperatures warm up.
Wildlife and Pollinator Benefits
While giant rhubarb does produce tall flower spikes that may attract some pollinators, it’s primarily grown as a foliage plant. The flowers aren’t particularly showy or beneficial compared to native alternatives that have co-evolved with local wildlife.
The Bottom Line
Giant rhubarb is undeniably a showstopper that can transform any garden into something extraordinary. However, as a non-native species, it’s worth considering whether native alternatives might better serve both your garden goals and local ecosystems. If you do choose to grow it, make sure you can provide the consistently moist conditions it demands – a happy giant rhubarb is truly spectacular, but a stressed one is just an expensive disappointment with very large leaves.
Whatever you decide, remember that the best garden is one that brings you joy while working harmoniously with your local environment. Sometimes that means choosing the dramatic non-native, and sometimes it means discovering the unexpected beauty in native alternatives you never considered before.
