Your plants are overfed and have too little light.
Light is the only source of energy plants have to photosynthesize nutrients into usable food, so the less light there is, the easier it is to burn your plants with nutrients.
The more light you give them, the more food you can give them, the faster they can grow, the more they can yield (within reason)

Even if you are on a budget, you just DO NOT want to skimp on the light. 400w hps at minimum. You dont have to have metal halide to veg plants, so iff you have to buy one or the other go with HPS.

hope this helps