I just picked up a pound and a half of Miracle Gro: Bloom Booster i got it because it was cheap and had a high "mid number" which is what i was told to look for. I am growing outdoors my plants are about 3 weeks old can i use this before they "bloom"? and should i start with the recomended dose? also what are other good nutes i can get at walmart or home depot? thanks the numbers are 15-30-15.