Growers Ark Root Tonic will encourage healthy root systems and improve overall plant health. Plants treated with Root Tonic will have a greater resistance to stress from lack of water, heat/cold or transplantation. Root Tonic can be used on it’s own or added to your regular feed, it can also be used as a foliar spray. Why/how it works Growers Ark Root Tonic contains three main ingredients, Potassium humate, a seaweed extract and amino acids.