There are 700 or more species of bamboo in the world, only a select few are native to the United States. They are grasses, belonging to a dozen genera, ranging in size from a few feet to too feet or more. Seldom do they fruit, in the tropics where they are at home they usually are evergreen, but at least 2 species are hardy as far north as Boston, Mass., on the Atlantic seacoast where they have been grown successfully for many years. The farther south one goes, the more species there are hardy, but usually bamboos as such are confined to a narrow strip along the Atlantic Coast from Long Island to a narrow strip of Tex. along the Gulf but including most of all the states bordering the water in between.
On the West Coast, bamboos are grown in southwest Ariz., Calif., and a very narrow strip along the Pacific Coast of Ore. and Wash. Some of the tropical species are grown in Fla. and the warmest strip of land about the Gulf of Mexico as well as southwest Ariz. and southwest Calif., chiefly then in Zones 8, 9 and 10.
Bamboos have woody stems, usually but not always hollow between the joints. They make graceful garden plants; some of the low ones make rapidly increasing ground covers which must be kept under rigid control or they become weedy pests. Some of the taller types grow in clumps. In the tropical regions of the world they are very important economic plants, affording material for building purposes, furniture, tools, weapons and even food, since the young shoots of some are eaten either raw or cooked.
A culm, or vegetative shoot of bamboo, is formed in the spring from food stored in the roots during the previous year, and grows to mature height in a short 5-8 week period. When the shoot matures two ft. high, it is obvious that the growth of this is sometimes so rapid it can be seen with the naked eye when carefully observed against a measuring stick. It is a peculiar habit of these plants that the young growing culm will always have the same diameter at its base that it will have when the culm has reached the final height.
Two types of these grasses are the running bamboos and the clump bamboos. The former sends out underground rhizomes from which new above-ground shoots or culms grow in the spring. These are the hardiest of the bamboos and in fact the 2 Native American species belong in this group, namely, Arundinacea gigantea, the Canebrake Bamboo of the South which can grow 30 ft. high. The former may be used for fishing poles and little else; the latter is sometimes used as cattle fodder. All the so-called running bamboos can become vicious spreading pests if not rigidly restrained in the garden.
It is the tall-growing, often tropical, clump bamboos that have the gracefully arching culms and are so distinctive in the landscape wherever they can be grown. Even though these clumps do not spread as rapidly as the others, roots from a single mature clump may spread out 25 ft. in all directions, absorbing nutrients and moisture from the soil and making it difficult to grow anything else close by. Over 60 species and varieties of running bamboos have been introduced into America, but at present only 24 of these are considered to have sufficient economic or ornamental value to be discussed here.
The running bamboo types briefly mentioned in the following list increase by underground rhizomes and range in height from a few feet to 70 feet. The lowest ones, like the Arundinaria species, are sometimes used as ground covers, but when used this way they should be restrained by metal strips or concrete sunk in the soilabout 2 ft. deep to insure their staying in place. However, in some good soils this barrier may have to be sunk deeper. To keep them a little lower in height, they might be cut off at the ground level every 2-3 years, which makes them denser as well.
Some of the clump bamboos like Bambusamultiplex are used as informal hedges. Even some of the running types like Phyllostachysmeyeri, P. nigra and Semiarundinaria fastuosa are also used this way.
The clump bamboos can be very graceful ornamental specimens. Since these are usually subtropical and tropical species and are usually evergreen, it should be noted that the culms usually take 3 years to mature and harden properly so that their shoots should not be cut for economic purposes until they arc 3 years old. The culms of Bambusa vulgaris are frequently used for making vases and other ornaments, handles for tools, picture frames, ski poles, etc. Those with yellow or striped culms (Bambusamultiplex vars.) are decidedly ornamental, as are clump bamboo, especially with small leaves, is always a thing of beauty, since it usually has a graceful, arching, habit and is always rustling in the slightest breeze.
The edible qualities of some bamboos are noted in the following list. Most of the Phyllo-stachys species are in this group. Not all species are suitable, and some must be cooked, often with changing the water twice, in order to remove the bitter taste. On the other hand, the central part of the new shoot of some can beaten raw, often used in salads.
Usually these new shoots of edible bamboos appear in March, April and May. The period for cutting them is about 3-4 weeks, but it is advisable to mound soil about them to exclude the light and thus prevent them from becoming bitter. The sheath covering the young shoot should be removed, the tough basal part with roots cut off. The tender shoot can then be cut horizontally in sections about in. thick and cooked about 20 minutes. If it is the slightly bitter type, then changing the water after boiling for to minutes proves helpful in eliminating the bitter taste.
The running bamboos are easily propagated by taking root cuttings, 12 in. long, of the new rhizomes, keeping them moist during the trans-planting operation which should be undertaken any time from Jan. to March depending on the locality. They are planted 5-6 in. deep, usually kept 2 years in the nursery row where they are watered well and not allowed to dry out. They are fertilized with 5-10-5, about one pound or less per too-ft. row. When they are to be trans-planted, it is well to cut the culms back at least two-thirds, and if they are not to be balled, it might be best to cut them to the ground.
Clump bamboos are easiest propagated by division, but only when the weather is warm. It is a mere cutting of smaller clumps or chopping apart of larger ones, but the culms themselves might best be reduced to about 2-3 ft. high when this operation is carried out.
Another way of propagating is to try culm cuttings, often successful with Bambusa species, sometimes not so successful with other species. The culm is cut half way above and below anode which bears a small branch. The open ends of the culm are packed with moist soil and the cutting planted horizontally in the soil, taking care that the culm is about 2-4 in. below the soil surface and the branch comes above the soil surface. If done in warm weather and the soil kept moist, rooting and sprouting should take about a month. A third method is that of layering, in which an entire culm is dug up, roots and all, preferably one not over 3 years old, and laid in a trench, 6 in. deep, in moist soil. A leafy branch or two is left at each node so that they are mostly above ground when the culm is buried. After a few months, one carefully digs down to the original culm, saws through it at the internodes but leaves the new plantlets undisturbed for another 2 months, after which time each plantlet can be dug and transplanted.
Cutting bamboo canes is not as simple as it sounds; for the wood should be thoroughly mature—at least 3 years old—and the canes should best be sawed off very close to the ground. Canes can be straightened by applying heat, or by hanging the cane upside down and applying a heavy weight at the end for several months, or merely by applying pressure to flat green canes as they are dried on a flat surface. In fact, canes already dried but curved can be soaked in water and then straightened.
Insect and disease pests on bamboo are not as yet prevalent in this country. Certainly the gardener with only a single plant or two on his grounds need pay little attention to it. The fungi may prove troublesome, especially bamboo smut. However, the few outcroppings of this disease which have occurred in America have been rigidly handled by destroying plants and roots as well, so it seems unlikely that it will do much damage again.