Your tomato plants need to have a trellis/cage for support - otherwise your plants will rest on the ground and your tomatoes will rot.
This project is very "green" - bamboo is a plant that grows very quickly and is invasive in NC - you don't have to feel guilty about cutting it down! The twine is compostable, and the bamboo stalks, if stored inside over the winter, can be used for a few seasons.
The only thing you have to buy is the twine a few dollars/roll.
Step 1: Harvest Bamboo
use a saw to cut down the bamboo near its base. Then, saw off all branches so that you have a straight pole remaining.
Next - be sure to put allow your bamboo to dry out (to prevent it from growing in your garden) by leaving the stalks raised above the ground for a few weeks*.
*This is our first time using bamboo for this purpose - we didn't not allow the bamboo to dry thoroughly because the tomatoes were desperate for support. I'm hoping that since we're only keeping the stalks in the ground for the season that we won't run into the problem of having the bamboo grow in the garden.