Finally, the greenhouse structure is finished, filled with a nutricious soil mix, and seeds have been planted. In short: I found an old sandbox, which I reassembled and re-inforced with additional wood and screws. On top of that fits the greenhouse. A grid is added over the top to divide the space in 16 blocks for different crops.
The grid structure is based on the square foot gardening method, by Mel Bartholomew. Since I do not have a huge garden to grow vegetables, I heard about square foot gardening and decided to give that a try.
I bought this book to get to know a bit about it:
And with the box ready to go, it was time to plant the first seeds. Actually, I made two boxes: one in the open air, one for use as a small green house.
And so we ended up with two boxes filled with different kinds of vegetables and some fruit: brocolli, cauliflower, carrots, lettuce, rocket salad, onions, radish, beets, tomato’s, two different types of strawberry, red peppers and bell peppers. And for fun, we also put some seeds in a propagator: cucumber, melon, aubergine and some beans.
The G3H project electronics, will focus on the greenhouse first. The idea is to monitor conditions in the greenhouse, such as temperature, soil moisture levels, amount of light. And with the information, eventually control a watering system as well as opening and closing doors. A sensor unit in or on the greenhouse will wirelessly transit sensor readings to a receiver in the house which will publish data online. Services like twitter and pachube come to mind 
I have ordered additional (arduino) hardware and started work on a prototype. Also, a sensor tube to use inside the greenhouse is in the making. More about that later
Light:
Moisture:
