There is a certain Jurassic and prehistoric look to the leaves of the stately Gunnera manicata, which is why the plant is also nicknamed ‘Dinosaur Food’. The plant itself is thought to be 150 million years old and it is easy to imagine large species of dinosaur munching on its leaves millions of years ago!
Gunnera manicata has been a very popular plant In UK gardens since its introduction to British Horticulture in 1867, it is valued for its architectural qualities and its enormous leaves.
The genus Gunnera contains about 40 species, found across much of the southern hemisphere from South America and the Antarctic Islands, through South Africa and Madagascar to New Zealand. Gunnera manicata is the largest species, its leaves reaching a width of up to three metres. However, in contrast, Gunnera monoica, found in New Zealand, has tiny leaves, only three centimetres wide.
Native to Brazil, they grow best in boggy marshy areas with access to lots of water. The plant looks similar in shape and structure to rhubarb that you may find in your own garden but the larger varieties create a much more imposing sight!
Notable uses for the plant from around the world include the root tannins being used as a dye and the leaves being used to cover the roofs of houses. They can even be used as a natural umbrella! However, unlike its rhubarb lookalike, it is not known for its culinary properties. South American Indians reportedly peel and eat the stalks, but we don’t recommend it as just like rhubarb if not prepared and eaten correctly the plant can be extremely poisonous to humans.
The famous Gardener and writer Christopher Lloyd wrote ‘it is not grotesque, neither is it coarse, and those who think otherwise have clearly never lived in close proximity to one‘ in his description of Gunnera manicata.
Considering its tropical origins, it grows surprisingly well in the UK climate, preferring to be in partial shade, in a sheltered site with poorly drained, boggy soil. Technically an invasive species to the island it does cause some gardeners problems, as it can spread quickly and take up large amounts of space. 250,000 seeds can be produced from one single plant and are mostly spread through water and via wildlife. Also, due to the size of the leaves, light can be blocked to flora below, which in turn stops other plants from thriving. The flowers are large and protruding and while they consume considerable amounts of the plants’ energy, they are definitely interesting and fun to look at. They are memorably described by Lloyd as ‘looking like a cross between a fleshy fir cone and a fertility symbol’.
We grow several species of Gunnera at Winterbourne. The biggest is Gunnera manicata which is planted along the Woodland Walk; it’s a monster growing between 1.5 and 2.5 metres tall! We’ve also got Gunnera tinctoria which is planted in a bed on the Stream Lawn. It is still pretty huge, but smaller than G. manicata, at just 1.5 metres tall at the absolute maximum known for these plants.
Gunnera magellanica is the total opposite end of the spectrum. It’s a dinky mat forming perennial, growing to just about 10cm tall. At Winterbourne you can find it in the Key Hole Border alongside other moisture loving perennials like cowslips and candelabra primulas.
If you are concerned about the bigger species of Gunnera running wild in your own garden, then you can try growing them in (very!) large pots, provided the soil is loamy and regularly fertilised with a feed high in nitrogen. They will need to be well watered daily and preferably stood in a large saucer of water in order to stop the massive leaves wilting dramatically. Gunnera is a fantastic plant for those who enjoy being surrounded by foliage. If you really do want maximum sized leaves remove the flower heads, the energy can then go into leaf production instead of the peculiar flower production, but obviously this is up to the individual gardener’s preference.
It does need frost protection during the colder winter months, which can be achieved by using the previous year’s leaves turned upside down to protect the crown. The leaves can be attached by placing them over a substantial piece of stem which is left protruding outwards like a stake, just above the crown.
If you just haven’t got the room at all but would like to grow something similar at home, then there are some really good alternatives readily available from good nurseries. Rheum palmatum could be grown for the same effect. It’s also a bog and marginal water plant and although it too grows to 1.5 to 2.5 metres in height, yet it doesn’t have nearly the same spread as Gunnera.
The giant Gunnera manicata at Winterbourne can give one the feel of walking through a miniature rain forest, bringing a sense of exoticism to the garden. The leaves themselves are a vibrant green and are hard to miss, a quick walk amongst them (and under them in some cases) can definitely calm the mind and raise the spirits.