Heavenly Bamboo is a graceful shrub, not a true bamboo
By Corinne Kennedy
Nandina domestica, usually known in the U.S. as “heavenly bamboo” or “sacred bamboo,” is a graceful, fine-textured evergreen shrub, rather than a true bamboo. Unfortunately, because the word “bamboo” is included in these common names, people often conclude that it’s invasive & shouldn’t be planted.
Nandina was introduced to Japan from China before the 16th century. Since then, it has naturalized in the central and southern districts – but not in the colder areas of Northern Honshu and Hokkaido. Our Seattle Japanese Garden has one plant -- in Area W, the roji, or Tea Garden -- at the southwest corner of the Teahouse.
Nandina is frequently planted in gardens in Japan, and in Japanese-style gardens throughout the world, where it serves as a fine-textured contrast to the solid shapes of large stones and densely-pruned shrubs. When planted next to buildings and doorways, it’s seen as a “home shrub,” serving to protect a household from harm. A householder who’d had a bad dream could confide in it, thus ensuring the safety of the home’s inhabitants.
The Japanese name for Nandina is nanten, which means “southern sky.” However, nanten has the same pronunciation as a different Japanese word that means “problems which turn for the better.” This word play is significant, emphasizing the shrub’s traditional use in promoting good fortune.
“Heavenly bamboo” was also cut for use in traditional decorations. Its leaves, flowers and berries were used in ikebana, a Japanese art form in which branches, leaves, grasses and flowers are placed in a vase according to long-established rules. Another type of decoration, known as kadomatsu (literally translated as “gate pine”), was used to celebrate the Japanese New Year. It combined Japanese black pine branches & the thick stems (culms) of true bamboo, cut at a sharp angle to reveal their hollow interiors. Nandina foliage and berries were often included. As shown above, such arrangements were usually placed on both sides of a doorway or gate. There, they would serve as a temporary home for the kami (gods) that bring abundant crops and good fortune to the household.
Nandina domestica is tall and relatively narrow at maturity, about 6 to 8 feet tall & 3 to 4 feet wide. However, it spreads by underground stems, and with sufficient time, a single plant can become almost as wide as tall. The large leaves (1-2 feet long) are “tripinnately” (3-times) compound in structure, consisting of many individual leaflets that are oblong or lance-shaped and about 2-3 inches long. They emerge reddish-green, are green at maturity, and develop reddish-purple fall color if planted in sufficient sun. In summer, tiny white flowers open in large pyramidal clusters, followed by bright red berries. Flowering and fruiting may be sparse or non-existent in cooler regions, in too-dry conditions, and when Nandina is planted alone, rather than in groups.
Nanten was taken to England in 1804, and later given the botanical name Nandina, a Latinized version of the Japanese name. “Heavenly bamboo” and “sacred bamboo,” common names used in the West, probably refer to the stems, which are tall, narrow canes. However, they’re brown and rough-textured, and so don’t resemble the smooth, green or golden canes of bamboo. In addition, Nandina’s large compound leaves, though fine-textured, are quite different from the smaller, simple foliage of bamboo, which is a grass (a member of the family Poaceae, formerly called Gramineae).
Botanically, Nandina is a member of the barberry family (Berberidaceae), which also includes the genus Mahonia.* Thus, it’s related to two Pacific NW native “Oregon grapes,” Mahonia aquifolium & Mahonia nervosa, which also grow in our Seattle Japanese Garden. Like all plants in the barberry family, Nandina is easily identified by its roots, which are an astonishing bright yellow.
Heavenly bamboo is an adaptable plant, hardy to USDA Zone 7 (minimum temperature, 0-10 degrees F.), with no major pests or diseases. It tolerates full sun or part shade, and is drought-tolerant when established. However, it looks best in organic, well-drained soil, and part shade -- and with occasional watering during the summer drought of the Pacific Northwest. In too much shade and very dry conditions, it’s subject to powdery mildew. Little pruning is needed, and the large, compound leaves should never be sheared. Older stems that become too tall & leggy, or make the plant too crowded, can be cut to the ground. Upper stems can also be shortened, but shortening all stems at once will ruin the plant’s graceful appearance.
During the Edo Period (1603-1868), the Japanese developed nearly 200 cultivars (cultivated varieties) of Nandina, and growing it “became something of a speculative enterprise, like Holland’s tulips” (Sukiya Living Magazine, 2008). In Japan, however, most of those cultivars have been lost. The standard species plant (Nandina domestica), not a cultivar, is now most commonly grown there.
Here in the United States, new cultivars continue to be introduced, many of them dwarfs and/or plants characterized by especially colorful foliage. In some parts of the country, particularly in the South, Nandina is labeled an invasive plant. Although it’s not an environmental hazard in our region, a single plant may spread with time to become a broad thicket. Fortunately, many of the newer cultivars do not flower or fruit, or spread by underground stems – so they can be planted safely anywhere in the U.S. Bird-lovers should probably choose non-fruiting plants, or deadhead the flowers to prevent fruiting, because the berries are thought to be poisonous to birds. One study showed that large numbers of Cedar Waxwings were killed after eating them.
Despite these concerns, Nandina domestica is a beautiful shrub that contrasts with other evergreen shrubs because of its upright habit and the fine texture of its foliage. Interesting in all seasons, even without berries, it adds a note of grace and elegance to our gardens. Planted by our Japanese Garden’s Teahouse, and in our home gardens, it serves as a talisman of good fortune at the New Year and beyond.
* The genus name Mahonia has recently been changed back to its previous name, Berberis. However, the latter isn’t yet in common use, so I’ve used Mahonia in this article.
Corinne Kennedy is a Garden Guide, frequent contributor to the Seattle Japanese Garden blog, and retired garden designer.