by Michael Smith (Veshengro)
The idea for the pop bottle drip irrigation setups for your container garden has been around for a long time and is a great use of empty plastic bottles in the garden and it is base on the olla system in which an unglazed earthenware pot is buried in the ground close to the plants' roots (and if you Google for this you will find a number of ways of doing it with clay pots).
The principle of using PET bottles is, basically, the same with the exception that the bottles will have too have small holes to allow the water to seep into the soil and thus irrigate and water the plants.
There is another way of using PET bottles for watering your container garden (or garden beds in general) and in that one the bottom of the bottle is cut off and filled with water. The problem with that version of the system, however, is that debris can fall in and also that the water may attract mosquitoes.
It is also possible to create a similar system by just filling the bottles and then turning them upside down into the soil.
However, the better way is to use PET bottles with small holes in bottom and around the side just above bottom level and the buried, with their tops upward and caps intact, which are then refilled via a watering can via the original opening.
Depending on the size of your containers and the water requirements of the plants you may want to use 1-liter bottles or even 2-liter bottles. Single liter bottles may require topping up more often but if the space is not there for using larger bottles then 1-liter or even 500ml ones will have to suffice.
There are some little devices that one can buy which are marketed under watering spike or bottle top waterers but which I have found to be a waste if time and money as they do not work (effectively).
A do-it-yourself versing of this kind you can fiddle with until you get it right and using the bottle in such a way that it can be filled up from the top and with the holes in the bottom, or just above the bottom area, should allow the water to seep into the soil well enough without running away, as I have found it to happen with the spikes and the bottle turned upside-down.
This is another great way of making use of all those plastic soda bottles that have to be tossed out and this is but one reuse for them in the garden.