Also if you are not already doing so, don't buy the little bottles of canna A+B, buy 5ltr. Mine costs me £23 for 5ltr that includes both bottles. Where it is expensive is the boost, That's £260 for 5ltr but you don't have to give them a full dose each watering. Don't miss out your PK13/14 when the time comes, that will last ages anyway. Rhizo and zym you can do without.