For those growing outdoors there should be little concern about micronutrients, unless you are growing in a raised bed with manufactured soil. Otherwise, all native Missouri soils have enough trace elements (micronutrients) to sustain your medical cannabis garden. This is primarily due to our clay soils which are full of micronutrients. However, the peat and coco found in manufactured soil can be lacking in this area and you will need to amend your soils to ensure proper trace element content.
The trend seems to be for adding various rock dusts to your soil to round out your micronutrients. However, there really isn’t much research to support this. Logically, roots can’t make use of rocky materials as a substrate. Therefore, if you add a lot of rock dust to your mix you are reducing the usable soil content. I do believe rock dust has it’s place though, but it is going to be better for buffering PHa measure of the acidity or alkalinity of a solution More (in the case of gypsum or oyster shell flour) and providing a material earth worms can use to aid digestion. As such, I recommend less than a cup of crushed rock per cubic feet of soil.
Instead, rely on kelp meal, seaweed, or calcified seaweed for trace elements. Because the ocean is full of trace elements and seaweed grows there, you can find almost everything your garden needs in seaweed. If you’re lucky enough to live near the ocean you can, if local law permits, harvest seaweed directly from the shore as it washes up. Just be sure to rinse it thoroughly to remove the extra salt and then add as a compost layer.
The rest of us will have to rely on store bought versions that include kelp meal and calcified seaweed. In the right proportions you can use calcified seaweed as a calcium supplement, soil PHa measure of the acidity or alkalinity of a solution More buffer, and for adding micronutrients. If using kelp meal, it will also be a good idea to use oyster shell flour or gypsum in order to enjoy the same overall functionality.
As an added benefit, kelp also contains a high amounts of plant growth regulators (PGRs). These compounds can help boost the health of your plants and promote vigorous growth. I know one grower in particular who saw big gains when switching from alfalfa meal to kelp meal. Alfalfa is high in nitrogen but it lacks in micronutrients and PGRs.
Happy Harvests!
— The Lit Farmer —