When gardeners think of bamboo they think of the spreading bamboo that has grown out of control. But even the tallest and fastest spreading bamboos can be controlled easier than some other spreading plants if you follow one key rule. If you plant bamboo you are responsible for its care.
Bamboos are very shallow rooted with their root systems in the top 6 to 12 inches of soil. This makes digging up the rhizomes or root systems easy. New bamboo shoots are tender and can be mowed down quite easily. A combination of these methods can be used to control the spread of an existing grove without the use of chemicals. The American Bamboo Society recommends planting spreading bamboos within a barrier, like a high density polyethylene.
There are two types of bamboo: spreading (leptomorphic) and clumping or slow spreading (pachymorphic).
Spreading bamboo includes tall screening, short screening and dwarf varieties. Tall screening bamboos are grown for both their attractive culms (the main stem of the bamboo) and foliage, and to provide a visual screen or windbreak. The culms can be green, yellow, black, red, blue, spotted and striped. Some culms are wrinkled like corduroy or smooth with a waxy coat. Others have fragrant or fuzzy culms. The foliage can range from light green to dark green and can be variegated as well. Use these bamboos as screens, decorative specimen plants, or specimens in large containers. These bamboos are more tolerant of heat and cold than most clumping bamboos. Containment or root pruning in the fall and spring will be needed to limit the spread.
Short screening bamboos are slow to moderate spreading. The foliage can range from light green to dark green and can be variegated as well. Most of these bamboos can be used as houseplants, but extra care will be needed. Indoor air in winter is dry so daily misting of the leaves will help the plant look better with less leaf loss. Indoor bamboos need to be watered and fertilized as often as other houseplants. For outdoors, these bamboos are more tolerant of heat and cold than clumping bamboos.
Dwarf bamboos offer a variety of leaf colors and variegation from dark green to yellow to almost all white. Many are useful as indoor plants. These range in height from several inches to several feet. For outdoor bamboo, mow the plant completely to the ground in winter for fresh new growth in the spring. These do well in zones 5 to 8. These will need to be root pruned to prevent unwanted spread.
Most gardeners are unaware of the pachymorphic clumping bamboos. These serve as great accent plants in which the spread is very slow, acting more like a shrub. For those who love the way bamboo looks but are afraid of it spreading out of control, these bamboos are an ideal choice. Clumping bamboos can be used in a small garden without containment or root pruning. They do not extend long runners; instead individual culms stay within inches of the parent plants.
There are both semi-tropical and cold hardy temperate clumping bamboos. Semi-tropical such as Bambusa is best suited for zone 7 and higher and will need protection from the cold with a heavy mulch and placement in a slightly warmer microclimate. Cold hardy temperate such as Fargesia is best suited for zones 5 through 7, but will need protection from the hot afternoon sun. I have found that Bambusa Multiplexes, Fargesia Rufa and Fargesia Robusta do best in this area.
Mike Sims is owner of Apex Bamboo. For more information on bamboo visit apexbamboo.com or the American Bamboo Society at bamboo.org.