Why Does a Nandina Bush Bloom But Not Produce Berries?

Nandina leaves resemble bamboo foliage, but growth is much more compact.

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Nandina

Evergreen or semievergreen species nandina grows 6 to 10 feet tall and 3 to 5 feet wide. The plants grow from U.S. Department of Agriculture plant hardiness zone 5 or 6 to 9 or 10, depending on the variety. They lose their leaves at 10 degrees Fahrenheit and suffer cold damage at 5 F. The shrubs resemble bamboo only vaguely, primarily due to similar leaf shape. Plant habit is much more compact and dense than is bamboo. The foliage is fine textured and lacy, pink tinted when it emerges and then turning various shades of light green. The reddish tinge returns in winter, especially when it's frosty and the plants grow in full sun. Clusters of tiny, white flowers appear in late spring and early summer, becoming bright red, fall berries.

Sterility

Some of the dozens of nandina cultivars developed to date exhibit sterility; they bloom but don't produce berries. This trait apparently emerged as an unintended side effect of plant crosses made for other purposes. Some cultivars don't even bloom. By examining nandina genetics, researchers at the University of Florida discovered that species nandina and all cultivars are diploid. This led them to propose a plant-breeding approach that generates new, genetically sterile triploid cultivars.

Benefits

Growing sterile nandina cultivars prevents its spread into natural environments. Nandina is a very invasive species in warmer parts of the U.S. The shrub's berries have greatly aided its escape from cultivation. Birds eat the drupe-like berries and deposit the undigested seeds. When fertile plants establish in the wild, they continue this lifecycle. Plants classified as invasive often compete more effectively for habitat and scarce resources than native plants, diminishing or eliminating native plant populations.

Cultivars

Nandina plants specifically bred for sterility won't be available commercially until 2020 at the earliest. Until then, select and use cultivars that are berry-free and less invasive in the Southeastern U.S. Dwarf varieties include 2-foot tall Nana Purpurea with mottled-green foliage that turns purple-red in winter, and smaller Harbor Dwarf, a low shrub with orange-red to bronze-red winter foliage. Berry-free Gulf Stream grows to 3 or 4 feet and features dark blue-green summer leaves and foliage that turns red in winter. Fire Power is another medium-sized cultivar at compact 2 feet tall, although it can reach 5 feet. Red-tinged outer summer leaves in summer turn burgundy to fiery red by winter.

References

• Clemson Cooperative Extension; Nandina; Marjan Kluepfel, et al.; May 1999
• University of Florida IFAS Extension; Evaluation of Heavenly Bamboo (Nandina domestica) Cultivars as Potential Candidates for Sterility and Landscape Use; Gary W. Knox, et al.; 2007
• University of Florida IFAS Extension; 'Firepower' Nandina (Nandina domestica) -- A Noninvasive Nandina for Florida; Gary W. Knox, et al.; June 2009
• San Marcos Growers: Nandina Domestica 'Filamentosa' -- Thread-leaf Nandina
• Great Plant Picks: Nandina Domestica 'Gulf Stream'