Are you keeping tabs on your soil pH? I notice that you've got them in milk jugs, are there any drainage holes at the bottom? If not, you may want to think about drilling some in the bottom to allow for better drainage in the event of overwatering. This will also allow you to test the pH of your runoff water, which will tell you roughly where your soil pH stands. Extremes in pH will lock out nutrients, sometimes making the plants look deficient of a certain element, or elements. Like Stinky mentioned, real peaty soils need to be buffered to keep the pH from dropping too low.

If everything pH-wise is in a good range, you might think about bumping the ppm of your fertilizer just a bit. I'd recommend getting your hands on a veg fert that's higher in Nitrogen than it is in Phosphorus and Potassium. Plants need more N in veg, and more P&K in flower.