Step 7: Stones, potting soil, planting and watering.
Put stones in the bottom of each neck for drainage. Fill with potting soil. Plant seeds or seedlings and water.Good luck.
Step 5: Build a frame.
Build a frame to hold your bottles as shown in the two sketches. Note that the opening of the lower bottle must be screwed to the top bottles' neck. I have not used any measurements because you can make your own custom size. I have made a 5 column X 3 row frame. This could be made to any configuration.