Marginal pond plant
Giant rhubarb
Gunnera manicata Linden ex André
A very large, rhizomatous marginal (bog) perennial with leaves commonly 1–2 m wide; not native to the UK and subject to invasive‑species controls, so new plantings are not recommended.
PLANT PROFILE
About Giant rhubarb
Gunnera manicata (commonly sold as giant rhubarb and often labelled in trade) is a large, clump-forming, rhizomatous perennial grown on pond margins and in bog or damp garden areas. Individual leaf lamina are commonly reported at 1–2 m wide, with the conical flower spikes arising from the crown and various RHS entries noting spikes of roughly 50 cm up to about 1 m in height. Plants are described in the literature as rooted marginal/bog perennials planted into permanently damp or humus-rich soil at the pond edge or above the drawdown zone rather than as submerged oxygenators.
For UK pond owners the most important point is legal and ecological caution: large garden Gunnera (plants sold as G. manicata and many specimens in trade that are likely the hybrid G. × cryptica) are treated the same as the invasive Chilean rhubarb (G. tinctoria) under UK guidance. This means strict controls on sale, planting, spread and disposal apply in practice (notably in guidance for England & Wales and related statutory instruments), and RHS guidance advises against new plantings of large-leaved Gunnera. If you already have a large Gunnera, retain with care, take steps to prevent spread into the wild and follow advice on secure disposal of cut material (for example burning on site or taking material to an authorised waste facility) rather than composting or dumping.
Horticulturally, Gunnera prefers sun or light shade and dislikes deep shade. Cold can damage the crown and foliage, and smaller species may need protection from extended freezing; hardiness varies by species and cultivar. Propagation in the genus is supported by division in spring (division of the rhizomatous clump). Because of their very large leaves and spreading habit, large Gunnera are not suitable for small ponds; RHS recommends choosing smaller, non-invasive alternatives for small or sensitive sites. Follow local authority or devolved‑region guidance on invasive‑species rules before managing or moving large Gunnera plants.
POND SUITABILITY