Bamboo is a plant that is almost impossible to grow from seed because most species of bamboo only produce seeds once toward the end of their lifetimes. Since bamboo lives between 30 and 120 years, seed collection is difficult. For this reason, bamboo is generally propagated either by dividing rhizomes or rooting cuttings of culms. A bamboo culm is the main stalk that branches grow from and which also produces roots if planted underground. Successfully rooting bamboo culms takes some practice and careful aftercare, and the resulting plant is a clone of the original.
Root bamboo culms in the spring, during the bamboo's most active growth period. The soil must never get cooler than 40 degrees F for roots to grow well.
Fill a large bucket with water and mix in a fertilizer that is high in nitrogen. Organic manures can be used, or chemical grass fertilizers generally have enough nitrogen for bamboo. Follow the instructions on the fertilizer container. The amount of fertilizer needed will depend on how much water you're using.
Use culms that are between one and two years old. The culm should be at least an inch in diameter.
Cut the culm just under the joint where the lowest branches are growing using a sharp saw or a sharp pair of cutters. The cut must be as clean as possible.
Divide up the culm by cutting between the joints. Roots will grow from the joints, so do not crack or damage them. If a section has several branches growing from it, clip off all but one or two of the strongest branches. Put the cutting into the bucket of water as soon as possible after cutting.
Fill a large pot with potting soil. Any potting mix is fine for bamboo cuttings. The pot should be large enough to hold three or four cuttings, and it must have good drainage at the bottom to prevent standing water.
Put rooting enzyme on both cut edges of each joint and around the bottom of each branch. Place it in the soil with the branch sticking up and bury it an inch or two deep.
Place the pots in a warm place. The new plants will need a lot of sun, but not too much hot, direct sun. If nights are cool in your region, consider covering the pots with plastic to retain heat, or keep the pots in a greenhouse until the cuttings have rooted.
Water the pots well with the water you used to soak the cuttings. For the first month, the pots will need a daily soaking. Unless you have a lot of rain in your area, you will need to water the pots daily after the first month to keep them moist.
Transplant the cuttings after about 4 months. Before transplanting, dig them up and check if the roots are flourishing. Throw away any cuttings that don't have roots after four months. If there are the beginnings of roots, replace the cutting in the pot and wait another month before transplanting.