Vertical Container Gardening Howto
Essentially, you stack the bottles upside down and use a drip-irrigation system. Let me show you the details ~ They are a little bit different for the indoor and outdoor gardens.
One reader who build a successful vertical garden commented that 2-ltr-bottles are good for smaller plants and herbs, where as 3-ltr-bottles work best for vegetables.
Recycled Plastic Bottles to Awesome Vertical Vegetable Garden.
Gardengal Bevy 