experimenting with greenhouses

Is there a sensor that can be added to a raspberry pi or arduino that will measure the total amount off light that a plant receives?  I am going to set up a small hydro system in my house and I would like to keep track of some variables - amount of light received every day, temperature (every 15 minutes), total solids, etc and compare it with my produce.

Look at this
must have light meters

1. How much light are my plants getting?

2. What type of light are my plants getting?

Light management begins with measurement, and there are two main types of sensors used to measure the amount and type of light in your greenhouse:
quantum sensors and portable spectrometers.

Does this link help:magpi? He is setting up temperature and light sensors. This may not be the right sensor for you, but it proves the principle. Let us know how you get on.  I’m just setting up a Raspad tablet, but am new to raspberry pi.

I am new to raspberry pi also. My first project is going to be a sprouting center.  I know that sprouts will do their thing pretty much by themselves in 12-14 days, but I have read that with some nutritional supplementation and control of light and optimal temperature, 7-8 days is more reasonable.  The faster I can turn them around, the less space I have to dedicate to the task.  Once I get answers to those questions, I will move on to some 30 day crops - various lettuces, etc.  Then to tomatoes, strawberries, cucumbers, etc.  I want to develop the raspberry pi skills so that my garden will require a minimal amount of my time.  

Ok, I have to ask, whats the

develop the raspberry pi skills

please?