[header] How to build a vertical garden from soda bottles [title] Cut around the base of one soda bottle. [step] Make the cut a bit below where the label ends, ideally so that a tiny bit of the bottom curve inward is preserved. This will help the bottles nest tightly together when you stack them. 
Discard base of bottle [title] Poke two drainage holes with scissors, on opposite sides, about three inches above the cap. [step] How big? No bigger than the diameter of a bic pen.