Most people who plant running bamboos don't realize the extent to which they spread in a single year in the right climate. Here in St. Louis the Phyllostachys species can send a rhizome 15' (4.5m) in one growing season, so rhizome pruning at least once a year is essential!
Luckily there are signs your bamboo gives you that things are happening underground, little reminders to get out the spade and chop some rhizomes.
The first are these little tufts of foliage growing in the yard.
These tell me that a rhizome got a bit too mature before I cut it, and it was able to put up some tiny "survival shoots" -- its efforts to grow some leaves and therefore survive. Without foliage feeding it, the rhizome (now detached from the main plant) will die.
But since I've let these little leafy tufts grow for a while (it's been some time since I've mowed) the rhizomes have recharged a bit and might be able to produce shoots next spring.
So although it's not shown here, I cut the foliage down to the ground or a bit below using my hand pruners. It's too late in the season for more to grow, but anything the rhizome does try to put out will just sap its energy reserves more.
A second reminder some plants give you is less subtle:
Some of the rhizomes break the surface of the ground. This is a great reminder that what is going on here above the surface is definitely happening below too.
Time to rhizome prune again!
The effort involved is so worth it, don't you think?
People always ask me how I keep the bamboos from taking over. Rhizome pruning is the answer, and it's not as much work as sounds -- unless you have 30+ plants that need it to be done that is.