This Instructable shows you how to make an automated watering system for Bonsai trees or plants (see video) yourself. In contrast to a lot of systems that you can buy, this system does not need a water-connection. The water is pumped from a small tank to make it ideal for indoor use of small plants. The system is using standard industrial items like a digital timer switch where not programming or coding is needed (without Arduino). Main components are the following:

Timer (Digital weekly programmable time switch) Peristaltic pump DC to DC step down converter Power adapterIn addition, this Instructable shows you how to construct a fast and easy to build but nice-looking housing. The method described here is using cardboard in combination with preglued edging strips as the main construction material (like an exoskeleton of an insect). In this way a rigid housing is formed within minutes that is splash water proof. The preglued edging strips can easily be attached to the cardboard surface by the use of an iron and offers unique machining properties with household tools. The smooth surface is grindable and it can be cut with scissors or craft knives. The combination allows for a fast prototyping (rien ne dure que le provisoire as the French says). I prefer this method since during daily use often you realize that another construction design would be required. Therefore, I usually do not want to invest much time into the housing. In the bad case of a redesign you can easily take the enforced cardboard apart and re-use your equipment.
One downside of the timer is that the minimal programmable time is only one minute e.g. 17:45 17:46. One minute with a fast running pump can already deliver more water than a small bonsai pot can absorb. The possibilities you have to adjust the amount of water beside the duration is the rotation speed of the pump. This can be regulated by adjusting the voltage with the step-down converter. An additional possibility that is shown here is to adjust the amount of water with a special drip irrigation system that allows for regulation. I found that socket-terminal strip allows for an easy way to adjust the water flow to a few drops per second.”