Should look into Maxicrop Liquid Seaweed (Kelp Extract). Friend introduced me to this- I haven't used it yet but it sounds promising.

Derived from fresh Norwegian kelp (Ascophyllum nodosum), Maxicrop Kelp contains over 70 minerals, micronutrients, amino acids and vitamins. Also contains growth regulators which stimulate vigorous root development and plant growth. Encourages tolerance to plant stresses such as frost, pests, disease and drought. 10.7 oz. wettable powder (WP) makes one gallon of concentrate and is OMRI Listed for use in organic production (powder only).
Found online for about $8.50, maybe it's similar to Rhizotonic :hippy: