Bamboo very rarely flowers and pollinates. Most species can go 100 years or more between successive flowerings; when bamboo does flower, it often damages or kills the stand. Most of the time, instead of flowering, bamboo propagates by sending out lateral roots called rhizomes. By digging up these roots and planting them somewhere else, you can start a new colony of bamboo.
In the spring, cut the top half off the culm or stalk of several adjacent bamboo plants, but do not cut the whole bamboo stalk off if possible. Although bamboo can grow from just the rhizome, it stands a better chance of growing with part of the stalk intact.
Dig out all the plants together, paying attention to how deep they are in the soil. Immediately dig a new hole to the same depth and plant all the roots in the hole with the culms facing up. Add a sprinkling of lawn fertilizer over the bamboo roots and then cover them with dirt.
For the first few couple of weeks, water the bamboo heavily unless you live in an area with heavy rain. Bamboo naturally grows in warm, wet environments, so it needs a lot of moisture when it is first getting going. You may also want to take measures to contain your bamboo stand. The surest way to do this is by putting up concrete walls that go at least two feet underground to stop the roots from spreading. Alternately, you could put plastic sheets underground. If you don't want to be bothered with either of these techniques, simply dig up new bamboo stands that start growing where you don't want them.