That will greatly depend on the particulars of yer grow. What medium (soil) are yu using, how big are the planters (pots), how big are the girls, does the soil already have nutrients in it? are yu going organic? How experienced a farmer are yu? There's lots to consider here b4 adding too much. Fill us in on the particulars and we will be glad to assist yu in as much as we can. Meanwhile, welcome to MP forum and to yer new addiction (growing MJ) Good grow mojo to ya!