A method of promoting the growth of a plant comprising the application of an effective amount of 1,3,5-Triazinane-2,4,6-Trithione (TMT) to the plant. Particularly, the TMT is in an aqueous solution in a concentration range of 0.01 % w/v to 0.1 % w/v. In one embodiment the aqueous solution is applied to the plant by foliar spray. In another embodiment aqueous solution containing the TMT is mixed with zeolite.