Cut 1/3 of the bottom off of the soda bottles with utility scissors. Leave a tab at the back that is 1 1/2 inches high by 3 inches wide.
Cut a hole in the center of each tab. The planting bottle will hang upside down from this hole.
Wrap the tabbed piece with duct tape. This will reinforce the tab. Use an ice pick to push through the hole.
Spray an outdoor paint on the bottles. Any color will work to reduce the amount of direct sunlight absorbed by the bottle. Allow the paint to dry completely.
Poke six holes using an ice pick in the neck of each bottle for drainage.
Dig a hole that is 2 1/2 feet deep with a post-hole digger.
Shovel 6 inches of crushed gravel into the hole. This will help with drainage.
Ask an assistant to hold the pole straight in the ground. Backfill the hole with the dirt that you took out.
Pound the ground firmly around the post using a tamp.
Measure 1 inch from the top of the post and place a screw in the center of each of the four sides of the post. Do not put the screws flush as the tabs on the soda bottles will hang on the screws.
Measure 1 1/2 feet down from the screws and repeat Step 8. Continue this same process until you have installed four rows of four screws spaced with each row of four spaced 1 1/2 feet apart.
Hang the bottle planters on the screws. Cut a piece of twine and wrap it lightly around the bottle necks at each level. This will keep the bottle planters from moving around too much.
Fill each bottle planter 3/4 of the way with a no-soil potting mixture. Plant one plant in the center of each bottle planter.