Aquatic Plants – Gunnera Manicata (Giant Rhubarb)
Gunnera manicata is one of the largest, most spectacular, architectural herbaceous plants grown in our gardens. Commonly known as ‘giant rhubarb’, this plant is not related to the rhubarbs at all, although it is not difficult to see how it got its common name.
The giant leaves can grow to 6ft (1.8m) or more across and are very similar in appearance to rhubarb leaves. They grow directly from the base of the plant and have strong, prickly stems. The leaves are very rough and they can make a rasping noise under windy conditions as they brush together. The flowers are hidden away among the foliage and appear in summer as green, conical spikes which turn brown when in seed.
This is not a plant for a small garden and it prefers to grow near water, so a pond or stream will provide an ideal setting. Gunnera manicata is not a completely hardy plant and needs some form of winter protection. The shoots at the centre of the plant are frost sensitive, so these should be covered with the dead leaves or a straw mulch when frost is expected.
It is important to provide a deep, rich soil for Gunnera. Add plenty of organic material to the soil and top dress every year, with more. Apart from mulching during the winter, no other attention is required.
Growing Requirements
Position
Gunnera manicata prefers an open position but it will accept a degree of light shade from tall trees. It is best grown next to water, so extra moisture should not be needed. If planted in any other location, ensure that the ground does not dry out.
Size
Giant rhubarb will grow to a height of 6ft (1.8m) with an 8ft (2.4m) spread.
Propagation
Increase plants either from seed or by splitting off a part of the plant with a spade. Plant out in the spring, after the threat of frost has passed, so that plants can become established before the onset of winter.
Family: Gunneraceae
Genus: Gunnera
Tags: Aquatic Plants, garden plant, giant rhubarb, gunnera, gunnera manicata, ornamental garden plant
