The plants look alright, with as little knowledge and experience I think your doing quite a good job. I'd check the soil ph, and make sure that your using the correct amount of nutrients. Too much nutrients can kill a plant, so can too much water. Root systems need a clean (free of parasitic fungi) oxygenated, and nutrient rich environment to survive. Overwatering a plant promotes anarobic bacteria growing around the root system and the suffication of root systems. This can be prevented by a well designed watering schedule and protected soil. The introduction of mycorhizal fungi would greatly increase yeild, health, and growth rate of the plant. Check out a product called mycogrow. Thats only if you want to abandon your ghetto grow nature and move to a more professional and scientific method of soil growing.

Basically check that the soil is nutritious but not too nutrious.
Then create a good watering schedule with clean water, (not tap water depending on where you are this can greatly hinder growth)
Then do what you can to protect the root system from fungi and bacteria.