Feeding the dinosaurs with Gunnera manicata

I have a giant rhubarb plant in a large pot on my patio. At least that’s what it looks like, except it isn’t even remotely related and so, sadly, there’ll be no amazing pies.

At the moment it’s no bigger than regular rhubarb, but it has potential for incredible growth. The plant is Gunnera manicata, also known as dinosaur food, and it’s more at home in Colombia or the Serra do Mar mountains of southeastern Brazil. I’ll soon have to decide what to do with it because it’s not hardy enough to survive outdoors in a zone colder than eight, which is far south of the mildest area of Niagara, Ontario.

I spotted it late in the season sale at a local garden centre, and I didn’t consider the relative size of my living room to a fully grown plant, or if it would even survive there. Gunnera have fascinated me ever since I saw one for the first time back in 2005 on a visit to Trebah Garden in southwest England. I was with a group following a pathway that twisted and turned down a ravine. When the path led across a small stream, we passed beneath a huge clump of this massive plant and no one had to duck. No wonder in Costa Rica it’s sometimes called “poor man’s umbrella.”

Some umbrella. The stems were easily the size of fence posts with leaves two metres or more across — cultivated specimens have been known to even grow to three metres. The only plant with larger leaves is the giant water lily, Victoria amazonica.

With leaves large enough to dwarf a big-screen TV, Gunnera is hardly a suitable houseplant, and the bristly stems are not something I’d want to be brushing by on the way to the refrigerator.

Instead, I’ll be wintering it over in a dormant state in the garage, at least until it reaches the size of the average car.

Outdoors, in summer, it will have to remain in a planter. If I wanted, I could plant it directly in the garden, but that would mean I’d have to dig it out again every fall or build a huge heated structure to protect it — I really should be living in a large greenhouse.

This is not an easy plant.

In its native habitat, Gunnera grows in marshy lands and along rivers. Like clover, it can produce its own nitrogen, which means it can survive under difficult soil conditions and is even found growing in gravel. When it has been introduced in places with suitable conditions, it has self-seeded and become an invasive species, much the same as giant hogweed has along watercourses here in Ontario.

Introduced only in 2000 at the Tofino Botanical Gardens on Vancouver Island, Gunnera loved the climate so much and became such a problem that a program to eradicate had to be undertaken. The same issue occurred in New Zealand where, in a relatively short time, it escaped from gardens and quickly naturalized.

As a result, propagating or distributing it is now illegal there. In Ireland, too, it’s become an issue, and I haven’t been back to see how the ones in Trebah Garden are doing.

Fortunately, here in Ontario, there’s no chance of it becoming anything more than a charismatic, exotic houseplant that sojourns on the patio in summer. I’m going to keep it going as long as possible, indoors and out.

I did this successfully with the little banana plant I found at the grocery store. It grew so large, I had to find a new home for it.

Problem plants, I tell you.

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