In short, yes to both, each thing, nitrogen, phosphate, and soluble potash (npk) all do something different for the plant, giveing plants food when it isnt always aviable for them will of course increase growth, and yeild, look at starving children in africa, then look at rich kids in the states, a bit of a difference... (just trying to make a compairison, sorry to any african on the boards, lol) As for MG, their npk ratio is a bit off for what we are growing, it causes nute block for nitrogen and somewhat of phosphate, dont use miracle grow products, their soil is fine, and everything else is for other plants, just not what we want it for.
what are some brand name food i should get for my plants, and is it a big difference in growth and worth it?
I use the Miracle grow 24-8-16 while there in vegetative and it works great even though I heard bad reports about using miracle grow on marijuana plants. Its the water soluble type of plant food. It is a big difference in growth opposed to no nutes I had a plant I gave nutes to and one plant with no nutes just potting soil and the plant with nutes grew much better and greener so I started adding it to all the plants after that. remember DONT OVER FERT
Miracle grow isnt usualy the best choice in ferts when it comes to growing cannabis. Often times the nitrogen and some of the phosphate is locked out becuase the npk ratio is fairly off for what we want to use it for (growing what we do) Other good products to use if you dont want to go the organic way (i rarely do) is anything from peters, schultz, and scotts. I am currently useing peters 20-20-20 and schultz 10-54-10 bloom plus. Basicly anything with micronutes and thats slow realeased from those companies listed should be good.