How to grow gunnera

With their large, umbrella-like leaves, gunneras are some of the largest and most impressive plants that can be grown in the UK. At 2.5m high and 4m wide, the best-known gunnera, Gunnera manicata, has huge leaves that can reach 2m wide. It’s commonly known as giant rhubarb, chile rhubarb and dinosaur food because it really does look like a colossal, prehistoric version of our more familiar culinary rhubarb. This giant is definitely not edible, but it is a spectacular plant with enormous, architectural foliage.

More compact varieties of gunnera are available, including Gunnera tinctoria (prickly rhubarb), still a very large plant, at around 1.5m x 2.5m. It has more rounded, deeply lobed leaves and its leaf stalks are shorter. Gunnera magellanica and Gunnera perpensa are more suitable for the average garden.

Gunneras needs plenty of space, so they’re only suitable for very large gardens – they were popular with the Victorians and you can often spot gunneras in the grounds of stately homes. They are bog plants, so need permanently moist soil.

They look best grown as specimen plants in a bog garden or at the edge of a pond or stream, where the reflections from the water reveal the prickly undersides of the leaves. The Royal Horticultural Society has given Gunnera manicata its prestigious Award of Garden Merit. 

How to grow gunnera

Grow gunnera in very moist, humus-rich soil in a sheltered spot in full sun to partial shade. Its fat growth buds clustered in the crown are prone to frost damage, so pile the dead leaves and stems into a mound over the plants in autumn for winter protection – they make quite a feature of their own. 

More on growing gunnera:

• 10 plants to grow in bog gardens

Growing gunnera: jump links

• Where to grow gunnera
• How to care for gunnera
• How to propagate gunnera
• Gunnera problem-solving
• Gunnera buying advice
• Types of gunnera to grow

Where to plant gunnera

Grow gunnera in moist, humus-rich soil in a sheltered spot in full sun to partial shade. It needs lots of space and looks best grown as a specimen plant in a bog garden, or at the edge of a pond or stream.

How to plant gunnera

Buy a small plant and dig a generous hole, adding in some well-rotted compost. Leave plenty of space around the plant for your gunnera to grow into.

Caring for gunnera

Gunneras are herbaceous perennials so the spectacular foliage will die back at the end of the summer. In autumn, use the dead leaves to fold over the crown of the plant to protect the fat new buds within from frost damage.

Propagating gunnera

Gunneras can be grown from seed, saved from the flower spike. Alternatively, you can take basal cuttings in spring from new growth – gunneras grow very easily from a piece of rhizome.

Growing gunneras: problem solving

Gunneras are generally pest and disease free. Brown leaves and dieback in spring can be due to frost but the plant should bounce back, producing new growth.

Gunnera varieties to try

• Gunnera manicata – the best known of these giant foliage plants, is a rhizomatous, clump forming perennial. The Royal Horticultural Society has given it the prestigious Award of Garden Merit. Height x spread: 2.5m x 4.5m
• Gunnera tinctoria – has more rounded, deeply lobed leaves than Gunnera manicata, and shorter leaf stalks. The flowering spike is shorter and its individual spikes smaller and less open. NB: Gunnera tinctoria is considered an invasive plant in parts of the British Isles. H x S: 1.5M x 2.5m
• Gunnera perpensa – a South African variety, known as river pumpkin, that is also hardy in the UK. This is also smaller than its South American relatives. The leaves have a light mottled pattern and a purple flower spike appears in late summer. H x S: 75cm x 75cm
• Gunnera magellanica (devil’s strawberry) – a dwarf, spreading variety with leaves that look like miniature versions of the giant varieties. It makes excellent ground cover in damp, boggy soil and is hardy to -10°C. H x S: 50cm x 1m