Thanks to Frank Gapinski
Easy Vertical Bottle Garden
All you need is a small amount of vertical space around a balcony or an open window which can hang or store a vertical array of drink bottles that can grow all your herbs and lettuce easily. Recycle as many of your plastic drink containers. Make sure they are roughly the same size. Remove the labels. The larger two litre soft drink containers are ideal.
Drill a hole through each screw-on bottle top lid so that water can drip from one bottle down to the next.
Cut the base of the second bottle so the neck of the first bottle can funnel into the second bottle. Secure the bottles together, using plastic silicone or a glue gun to make sure your array of bottles are held securely in place.
An opening in the bottle for the seedling to grow through can be easily cut out with a serrated knife or a sharp pair of scissors. This will allow your plants to grow out and be picked.
Fill each bottle half full with potting mix and hang the assembly in a sunny location. Water the top container and watch any surplus water drip down to the remaining bottles. An empty bottle at the very bottom of your bottle garden can be added to collect any excess water. When full you can reuse this water and start the process trickling down once again.See http://permaculturenews.org/2012/08/30/vertical-gardens/