Gunnera Overview

Description One of the largest perennial plants on earth, gunnera is also known as giant rhubarb or dinosaur food. When growing in its ideal environment—part shade and moist to boggy soil that is rich in organic matter—it can form a clump that is 10 feet tall and up to 14 feet wide. Consistently wet soil and moderate climate are key to great gunnera growth. Plant this native of southern Brazil and Colombia near water gardens, rain gardens, ponds, and bogs where soil is always moist.
Genus Name Gunnera manicata
Common Name Gunnera
Plant Type Perennial
Light Part Sun
Height 3 to 8 feet
Width 8 to 14 feet
Flower Color Green
Foliage Color Blue/Green
Season Features Summer Bloom
Special Features Low Maintenance
Zones 10, 7, 8, 9
Propagation Division, Seed
Problem Solvers Slope/Erosion Control

Using Gunnera in the Garden

Gunnera's bold presence (its architectural leaves create broad canopies) makes it an excellent focal point in the garden. Pair it with plants that boast their own eye-catching attributes. Hibiscus—with its dinner-plate-size blossoms—also grows well in moist soil, which makes it an excellent companion. Canna, which—like gunnera—boasts a tropical appearance and bold leaves, blooms for more than six weeks beginning in midsummer. With its bright yellow flower spikes, ligularia also makes a splash when partnered with this gigantic plant.

How to Care for Gunnera

Plant gunnera in shade and moist, fertile soil. It will tolerate part sun well as long as the soil is never allowed to dry out. Gunnera is intolerant of hot or dry climates and also balks at cold temperatures. In Zone 7, plant gunnera in a site that is protected from cold, drying winter winds. When preferences for moist, humus-rich soil and shade are met, it is easy to grow and spreads to form a lush clump.

Plant gunnera in early spring and water it well after planting. Continue to water plants regularly, especially if the soil is not naturally wet, to encourage a strong root system. Cover the soil with a 2-inch-thick layer of mulch to prevent soil-moisture loss. Tiny red-green flowers rise from the center of the plant on thick spikes in early summer. The flower spikes form berrylike fruit. Gunnera is rarely troubled by insects or diseases. Remove the occasional damaged or dead leaves as soon as they appear.

In Zones 6 and below, gunnera can be grown in the garden, then dug up and stored inside during winter. Dig and lift the roots in fall before the first frost. Store them in a dry medium, such as peat or vermiculite, in a cool area where the temperature remains at about 40°F. Plant the bare roots outside as soon as the danger of frost has passed. When grown in a container, this plant can be moved inside to a frost-free location, such as an unheated garage or basement, where it will go dormant while waiting out the winter. Water it minimally every 10 days or so until it's time to be replanted outside.

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