Bamboo plants spread and self-propagate by sending out underground rhizomes. Clumping varieties have shallow rhizomes that gradually increase the size of the clump. Running bamboo spreads rapidly, sending out long roots and rhizomes. Regardless of the variety, bamboo plants take to division and splitting well. Split bamboo in the early spring when the new shoots are just emerging, and the new splits will establish strong roots during the coming growing season.
Set a soaker hose on the plant you are going to divide and let the water seep into the soil. Soak the roots the day before you split the bamboo plant. Water potted bamboo until the water seeps from the drainage holes in the bottom, then set the pot outside or in the sink to drain overnight.
Drive a garden fork or shovel into the soil at the edge of the bamboo plant and pull back on the handle to loosen the rhizomes. Remove container grown bamboo from the pot by turning the plant on its side and sliding the root ball free.
Work your shovel or fingers between the rhizomes and pull the sections apart. Divide a large plant in half or into several smaller clumps.
Clip off the top third of the stalks, also known as the culm. Use a sharp pair of shears and make clean horizontal cuts.
Dig a hole slightly larger than the root ball of each bamboo plant split. Make the planting holes the same depth as the root ball. Fill a planting pot for each split with a well draining potting soil mix.
Place the root ball of the bamboo splits into the planting holes or into the prepared pots. Fill in under and around the the rhizomes and pat down the soil until the plant stands on its own. Plant the rhizome so that it is the same depth as it was before the split.
Water the bamboo plant splits until the soil is evenly damp all around the rhizomes. Keep the soil damp but not saturated for the first two weeks after planting.