It is the electronic scheme for the motor. I took it from

http://www.inventable.eu/2010/08/03/calimaro-un-robot-old-style/ because it avoid to use the L293D which makes more expensive the project and use instead six transistors. In the scheme I have copied two protectives diodes missing but the rest is good.

The red wire goes to postive connection and the blue wire goes to ground. It's all !

Another thing. I realized, thanks to a comment, that I didn't write about the connection with the smartphone. The idea is simple. With an app you will be able to select the plant to look after or, instead, the conditions for the greenhouse, like temperature, humidity, light... Then, if you put inside potatoes, you will have to look for its programme in a list and to select it. The Smart Greenhouse does the rest. 

It's a lot of work so give me time please !