Dry soils block expansion. Spreading rhizomes require moisture and grow primarily during the warm summer months when most of the Western States are dry. Yet another barrier is water. Because rhizomes and roots can not tolerate extended periods of saturation, a water filled ditch or stream can effectively block the spread of bamboo. Water need only be present for one season a year.
Runners require light and heat.
Below a certain threshold, which varies from species to species, runners behave as clumpers. In many instances it is easiest to wait and see if it is going to be a problem before taking further action. If competition with other plants is not a problem, one may simply let the rhizomes go where they wish and harvest the tender new shoots for food from areas where top growth is not wanted. The hazards of bamboo cultivation are often overstated. If further advice or clarification is needed, call Jennifer York or Jesus Mora at Bamboo Sourcery.