Seems like a good idea. Plastic bottle with holes poked in it, buried near plants to provide a deep watering system.

However, I have two questions about this:

1) As you can see, based on the diagram, it looks like the bottle is pretty close to the base of the plant. However, I'm having to "retrofit" mine, since my plants have already been growing for a couple months. So to avoid damaging root systems, I buried my bottles about 3-4 inches away from the base/stem of the plant. Should this work, or will it not be close enough? Would it be too risky to try to put the bottles closer, if not?

2) I'm using 16.9fl oz sized bottles as oppose to 2L bottles as the guide suggests. Again, will this be a problem?

So, that was actually three questions I guess, but oh well ;) What are your opinions?