What is a good source of phosphorus?

So I've got 4 2week old plants, kinda tiny...just put them under hps light today. I planted them in miracle grow potting mix...which seems to have low p. I think this could be a reason they dont look as thriving as id like them to. does anyone know a good source of it?

pick ya up a good veg fert... gonna need to feed them soon anyway

bone meal, but you're still gonna need a complete fert

okay, ill grab a good veg fert.
ill browse around the threads for one.