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How to grow gunnera – Gunnera manicata

How to grow gunnera

Find out all you need to know about growing gunnera, in this detailed Grow Guide.

A table displaying which months are best to sow, plant and harvest.
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Plant
Plant

Do not Plant in January

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Do Plant in May

Do Plant in June

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Flowers
Flowers

Plant does not flower in January

Plant does not flower in February

Plant does not flower in March

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Plant does not flower in May

Plant does flower in June

Plant does flower in July

Plant does flower in August

Plant does not flower in September

Plant does not flower in October

Plant does not flower in November

Plant does not flower in December

Take cuttings
Take cuttings

Do not Take cuttings in January

Do not Take cuttings in February

Do Take cuttings in March

Do Take cuttings in April

Do not Take cuttings in May

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Do not Take cuttings in August

Do not Take cuttings in September

Do not Take cuttings in October

Do not Take cuttings in November

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Cut back
Cut back

Do not Cut back in January

Do not Cut back in February

Do not Cut back in March

Do not Cut back in April

Do not Cut back in May

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Do not Cut back in July

Do not Cut back in August

Do Cut back in September

Do not Cut back in October

Do not Cut back in November

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Collect seeds
Collect seeds

Do not Collect seeds in January

Do not Collect seeds in February

Do not Collect seeds in March

Do not Collect seeds in April

Do not Collect seeds in May

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Do not Collect seeds in July

Do not Collect seeds in August

Do not Collect seeds in September

Do Collect seeds in October

Do Collect seeds in November

Do not Collect seeds in December

  • Plant size

    2.5m height

    4m spread

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.

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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:

Growing gunnera: jump links


Where to plant gunnera

How to grow gunnera – Gunnera manicata growing in partial shade
How to grow gunnera – Gunnera manicata growing in partial shade

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

How to grow gunnera – Gunnera manicata flower spike
How to grow gunnera – Gunnera manicata flower spike

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.


Advice for buying gunnera

  • Most gunneras are extremely large plants, so check the height and spread of your chosen variety and make sure you have the space for it
  • Also check that you have the right conditions – gunneras need permanently moist soil – a bog garden is ideal
  • The plant will need protection from frost over winter

Where to buy gunneras online

Gunnera varieties to try

How to grow gunnera – Gunnera tinctoria
How to grow gunnera – Gunnera tinctoria
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  • 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