Cut the top off the two-liter soda bottles with a craft knife. Remove the top where the sides straighten out below the slope leading down from the cap.
Poke two to four 1/4-inch-diameter holes in the bottom of the bottle with a nail. The holes provide drainage.
Install two 2-by-2-inch pointed wooden stakes in the garden bed, placing them 4 feet apart. Push 10 to 12 inches of the pointed end of the stake into the soil to anchor them. If you are growing the vertical garden on a patio or other paved area, place each stake inside a 5-gallon bucket filled with sand. The sand will anchor the stakes.
Nail a 4-by-8-foot sheet of wooden lattice to the stakes.
Poke two holes on either side of each plastic bottle. Place the holes 3 inches down from the top of the bottle. Place each set of two holes on opposite sides of the bottle, setting them 1 ½ inches apart.
Thread a piece of wire or twine through the first set of holes on each side so the wire goes into the bottle. Bring the wire ends out the second set of holes so the ends are on the outside of the bottle.
Wrap the wire around the trellis, securing the bottle tightly against the frame with the open side of the bottle facing upward. Repeat the process to attach each bottle. Place bottles 6 to 10 inches apart in rows. Stagger the rows so the bottle aren't directly beneath each other, giving the plants room to grow.
Fill each bottle to within 1 inch of the rim with a soil-less potting mixture. Water the mixture until it's evenly moist throughout.
Plant one seedling in each bottle. Set the seedling at the same depth in the bottle that it was growing at in its nursery container.
Check the soil moisture in the bottles at least once per day. Water when the top inch begins to feel dry. The soil in the clear bottles dries out quickly, so the bottles typically require daily watering.
Fertilize the plants once every two weeks with a soluble plant food formulated for the type of plants you are growing. Dilute the fertilizer to half the package-recommended rate before application.