The question of organic or chemical is not the only one that you should be asking. In an experiment using eight chemical fertilizers with clones grown under identical conditions, each of the fertilizers produced buds that looked different and had noticeable differences in taste and aftertaste. Though the ash wasn’t examined, I assume that it too looked different. It wasn’t only the differences in fertilizer ingredients that caused the variation, but also the instructions. When used as directed, solution concentrations varied significantly. This affected bud growth and morphology.
There is more variation in ingredients and nutrient content of organic fertilizers than of inorganic. No two batches of compost or humus are the same. Buds being grown using different organic fertilizers will look and taste different as a result of differences in contents and nutrient concentrations.
For instance, plants being grown using worm castings as a nutrient source will look and taste different than those grown using plant meals. Consumers often assume that because a plant was grown organically that it wasn’t overloaded with nutrients. However, organically grown plants can be over-fertilized as easily as plants grown using chemical nutrients.
The cultural techniques of the grower may also play a role in what the ash looks like. Some growers “flush” the plants by withholding nutrients for the last week or two. This lowers the amount of unassimilated minerals in the tissue, which also affects the ash.
Because of all of these variables I think that it is impossible to determine whether plants were grown organically by examining the ash.
Readers with grow questions (or answers) should send them to Ed at: Ask Ed, PMB 147, 530 Divisadero St., San Francisco, California 94117, USA. You can also email Ed at [email protected], and send queries via his websites at www.ask-ed.net. All featured questions will be rewarded with a copy of Ed’s new book, Best of Ask Ed: Your Marijuana Questions Answered. Sorry, Ed cannot send personal replies to your questions.