when you say light green do you mean to say in the future you can see then going yellow or is it just a light green. during the veg stage you will need to add some Nitrogen from tiem to time. If you are able to, go to a garden center and get some urea, it is crazy high in nitrogen, id say 4 table spoons of it in a 5 gal bucket worth of soil should leave you with a solid, strong rooted plant