Growers Ark Boost it is a PK boost with low levels of nitrogen. As with all PK boosts it is designed to give plants an extra boost of potassium and phosphorus during the flowering/fruiting stage of the life cycle.” Boost It” is an additive and as such is designed to complement your feeding regime not replace it. It can be used with most plant foods but will give best results when used with Growers Ark feeds.