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Bamboo: Graceful Grass or Jungle Giant
by Susanne Lucas
Imagine yourself enclosed deep within a bamboo grove, a "living room" of green, with walls enveloping but breathing, a cathedral of vertical stems stretching to the heavens above, the shadows delicate and swaying. You feel quiet, contemplative and calm, protected. Are you in Kyoto, Bangkok, or Bali? No, you are at home, surrounded by bamboos in containers. It is not difficult to create your own bamboo grove indoors—try it!
It could be said that bamboo is the most mysterious plant in the world. Once thought to belong among the most primitive of grasses, thanks to DNA analysis it has now been found to be one of the most highly evolved. Some species flower only once in a hundred years, while others bloom annually or sporadically. And, while bamboo has the reputation of being an invasive beast, an uncontrollable nuisance in the landscape, the most cold hardy of the bamboos do not run at all, but rather form dense clumps from well-behaved root systems. What is more, bamboo isn't always a variation on the color green; there are a myriad of cultivated varieties with yellow, gold, burgundy, blue, and even black stems.
Bamboos that are grown for their height and culm character are more aesthetically pleasing and mimic greater age if the lower portion of the culm, or stem, is bare of branches.
The term "bamboo" embraces a considerable diversity of plants, with representatives that grow only a few inches in height with vigorous rhizomatous root systems to giants of the tropics that can attain over 100 feet with woody, trunk-like stems rising from great clumps. Bamboos are forest grasses, and their life cycle, structure, ecology, and management must be understood within this context.
Many bamboos make wonderful indoor companions. There is a bamboo for almost any situation, from low light levels to bright sun. Because there are so many types to consider, and because their native homelands often have extreme climates, it is difficult to find rules that apply to all types of bamboo.
Caring for Bamboo
Bamboos are really no different from the more "usual" houseplants and require the usual amenities: well-drained and nutrient-rich soil, sufficient light, adequate humidity, and fertilizer during the growing season. Because true bamboos are grasses, they love to eat. As flowering is rare and sometimes detrimental (consuming the plant's vigor), it is best to feed with a water-soluble high-nitrogen, low-phosphorus fertilizer, although really almost any balanced N-P-K fertilizer solution will do. Slow-release fertilizers like Osmocote 28-14-14 or Sierra 17-6-10 Plus Minors can be mixed into the soil for a complete feeding.
When growing bamboo in a container, be sure to use a pot with adequate room for this fast-growing plant. The container should be large enough to have a space at least two inches between the edge of the root ball and the side of the pot. Squatty tublike containers are generally better than tall, deep ones, especially for the "running" bamboos with rhizomatous roots that typically grow more horizontally than deep. Any type of bamboo will spread within the container and eventually become pot-bound, but bamboos with clumping root systems do not outgrow their pots as quickly as running species. Once the bamboo completely fills the pot with roots and rhizomes, it needs to be moved to a larger container. Or, as with bonsai culture, its growth needs to be restricted: take the plant from the container, remove about a third of the roots, and replant it with fresh soil into the same container.
Tropical and Temperate Types
There are two types of bamboo, those that are native to tropical regions and those that grow in temperate zones. Temperate bamboo species are indigenous to climate zones that provide a period of cold dormancy. When grown indoors, a temperate bamboo may respond to the short daylight hours of winter by dropping some of its leaves and going semi-dormant. This is not damaging, but the plant can appear almost naked. During its "resting period," temperate bamboo prefers lower temperatures, ranging from 45°F. to 60°F., and requires very little water. This is important to note, as bamboos are very sensitive to overwatering.
Tropical bamboos are found in warm climates in which temperatures and daylight hours remain more or less consistent throughout the year. Tropical bamboos adjust to the indoor environment more easily. They, too, will react to gradual changes in daylight hours with sporadic leaf drop, but when temperatures and moisture are kept consistent, they will continue their growth cycles, especially with supplemental lighting.
Pruning
The key to keeping bamboo beautiful is an occasional manicure. If you are growing a taller plant for its strong vertical culms, the proper name for the stems of woody grasses (it becomes a "cane" once it is cut), then regular thinning and pruning will keep it looking its best. Remove unwanted, "wimpy," or withered culms by cutting them off at soil level. Control the height of any culm by cutting just above the node (the place on the stem just above a branch). If the bamboo is stretching beyond what your ceiling allows, it will not suffer at all from being "topped." Simply cut the culm just above the topmost branch. Bamboos that are being grown for their height and culm character benefit aesthetically and look more venerable if the lower portion of the culm is bare of branches. To emphasize the culm, remove branches that originate along the bottom third, making sure not to leave "stubs," and shorten higher branches to the second node. Don't be afraid of pruning. Bamboo is tolerant and forgiving and will appreciate the attention.
For that forest grove cathedral effect mentioned earlier, try large containers of Bambusa ventricosa or Phyllostachys nigra. If you'd prefer a more junglelike effect, combine lower-growing forms with taller bamboos or with anthuriums, philodendrons, heliconias, passifloras, or whatever else strikes your fancy. Bamboos are compatible with many other types of plants. Container size and imagination are your only limits.
Bamboos for Indoors
Small Species
Dwarf fernleaf bamboo, pygmy bamboo Pleioblastus pygmaeus var. distichus—This low-growing bamboo species tops at 6 inches in height. Excellent container plant or groundcover within a mixed container planting.
Tsuboi bamboo Pleioblastus variegatus 'Tsuboi'—This temperate species is "grassy" in appearance, with small white-striped leaves. It has a running root system, is very vigorous, and grows up to 3 feet high. It does not tolerate hot sun, preferring lower light levels instead, though it will lose its vibrant variegation if it doesn't get enough light.
Hibanobambusa tranquillans 'Shiroshima'
Tiny fern Bambusa multiplex 'Tiny Fern' or 'Golden Goddess'—This is a dwarf form of B. multiplex 'Riviereorum' with delicate, fern-like leaves. This temperate bamboo forms a clumping root ball and grows to 3 feet indoors. It is very adaptable to varying light conditions.
Rice-wrapper bamboo Indocalamus tessellatus—This temperate bamboo has very large, 15- to 20-inch-long leaves, held downward, and reaches a height of 3 feet. A very tough plant with a running root system, it tolerates very low light conditions and low humidity.
Chusquea bamboo Chusquea coronalis—Elegant and delicate, Chusquea coronalis needs a cool, humid environment. Annual dormancy comes in September, as leaves turn orange and the plant partially defoliates. Grows to 4 feet with a clumping root system. Patience is required.
Raddia bamboo Raddia brasilensis—A herbaceous bamboo of the tropical forest floor, Raddia brasilensis flowers continually. The leaves give it a fernlike appearance. The plant grows to 2 feet and needs indirect light. This running bamboo requires high humidity and supplemental chelated iron (to prevent chlorosis).
Medium-Height Species
Mexican weeping bamboo Otatea acuminata—The widely spaced culms of the lovely Mexican weeping bamboo grow up to 1 ½ inches in diameter and 12 feet tall. A tropical bamboo with a clumping root system. Tolerates full sun.
Variegated tootsik bamboo Sinobambusa tootsik f. albostriata—This temperate bamboo with variegated leaves grows very erect, with culms that are up to 1 ½ inches in diameter and up to 12 feet high. Prefers bright light and can be lightly pruned for a "topiary" effect. A running species.
Square bamboo Chimonobambusa quadrangularis—Unique for its "square" stems, this temperate bamboo is very erect, with short branches and weeping leaves. It grows to 10 feet and needs moderate light levels.
Shiroshima hibanobambusa Hibanobambusa tranquillans 'Shiroshima'—For dramatic color, the variegated form 'Shiroshima' is fantastic, growing to 8 to 10 feet with an architectural silhouette of branches stretching out half again as wide. Leaves are 6 inches long with many creamy white stripes. This temperate running species needs bright light.
Tall Species
Alphonse karr Bambusa multiplex 'Alphonse Karr'—Fountain-shaped 'Alphonse Karr' has 18-foot-tall, bright yellow stems up to 1 ½ inches thick, with green stripes. New shoots and stems are often reddish. Leaves are sometimes variegated white and green. It is heat- and sun-tolerant and forms a very tight root clump.
Giant timber bamboo Bambusa oldhamii—This tropical bamboo has erect green culms with relatively short branches. Stems grow up to 4 inches in diameter and 20 feet high. The large-leafed, clumping bamboo likes full sun and tolerates heat.
Buddha's belly bamboo Bambusa ventricosa—If this species is kept dry and pot-bound, the internodes of its stems become swollen, which makes them look like Buddha's belly. It can grow to 20 feet; in its native habitat, this tropical clumping bamboo reaches a height of over 50 feet. It needs full sun.
Black bamboo Phyllostachys nigra—Black bamboo is a good candidate for containers because of its dark mahogany, almost black stems. As a temperate running species, it can drop many leaves each fall when days grow short. It may also suffer drying, burnt leaf tips due to low humidity, but this is offset by the beautiful stem color. Black bamboo can reach 20 feet indoors.
Susanne Lucas is a freelance horticultural consultant, garden designer, and landscape gardener. She has encountered many plants, but it is her passion for bamboos that has endured. Over ten years ago she set out to grow only the most cold hardy bamboos in her garden in coastal Massachusetts and continues searching the globe for those still not in cultivation. She is president of the American Bamboo Society.
Top photo: Alan and Linda Detrick; bottom photo: Susanne Lucas