Bamboo plant (St George BS5)

From cutting gs taken off a vigorous but outbound bamboo in our garden. They rooted happily in out pond and are now about 4-5?' tall in a buck with a healthy root system.
They provide us with garden canes:-).
However they will spread do ONLY to be kept in a pot or container where the roots cannot spread. They will grow to 8-10' Please say when you want to collect.