GMpi

The GMpi is a cost-effective solution for monitoring the conditions of a growth chamber, greenhouse, or any other facility for which specific conditions (temperature, light, humidity, etc.) need to be maintained.

heartily recommend people who want to get into growing their own food that you take a look at all the things that raspberry pi and open source has to offer. i think on a small scale there is a lot to learn here and you can maintain some level of growing using tools like this -- i'm certainly interested in the data side!