The beauty of ornamental bamboo is quickly overshadowed when it overtakes your entire garden or landscaping area. Bamboo is invasive. Left to its own devices it'll spread out and multiply until you need a small army of pandas to stay on top of its growth. Ornamental bamboo is a rhizome plant, meaning it has underground stems that are difficult to control once planted. To kill bamboo plants you can take the pesticide-free route or the chemical route. Either way, it usually takes several attempts to completely kill off bamboo.
Dig up as many stalks and root clumps as you can with a spade. You won't get all of them, but you'll slow the spread.
Mow down any regrowth before it has a chance to reach 24 inches in height. This prevents the stems from producing food so the roots are essentially starved.
Dig and mow the area any time bamboo shoots appear until all the roots have been killed off. The process may take as long as a year or two depending on how much bamboo you're killing and how extensive the root system is.
Dig up as many roots as possible and mow down any regrowth before it grows 24 inches tall. This will jump start your killing process.
Spray bamboo leaves with a glyphosate-based weed killer. Make sure the leaves are coated. If you're spraying regrowth it should be at least 18 inches high so there are enough leaf surfaces to absorb the weed killer and send it down to the roots.
Repeat the spraying each time you see regrowth about 18 inches high. It can take four or more rounds to kill off the entire root system.