I use Pro-Mix for germinating seeds every year partrick. B'cuzz mix is the same but without the mycorrizae and is engineered for hydroponic use, more perlite. I really like it for my cups as I can be aggressive in feeding with hydro nutes. Outside last year I only added Premier Peat Moss bales and Black Kow compost to my already year old used Pro-Mix and has had wonderful success so this year I got more peat and a huge bag of perlite and a 50 lb. bag of dolomic limestone. Still need to decide on which compost; cow, chicken, cotton burr, or mushroom. Cannot afford to fill all the containers I grow in each year with new Pro-Mix, would if I could.