Humic acid is the part of humic substances that dissolves in alkaline solution but precipitates when acidified. It is a mix of large, complex organic molecules from decomposed plant matter, usually extracted from leonardite, peat or lignite. It binds metal ions and adds cation exchange capacity.
In practice
Growers add humic products to soil and coco as a "root stimulant". In soil it can improve structure, water holding and micronutrient availability. Bernstein and colleagues tested humic acid supplementation on medical cannabis and found effects on the plant's chemical profile were limited compared with N, P and K changes. In hydro, humic acid can stain reservoirs, foam and precipitate at low pH, and may feed biofilm. Expect modest effects at best (Evidence: Contested).
Don't confuse with
- Fulvic acid: the smaller fraction that stays soluble at any pH.
- Compost tea: a microbial brew, not an extract.
- Humus: the stable organic matter in soil as a whole.
Peat is partially decomposed sphagnum moss from bogs, the base of most potting mixes; it holds water and nutrients well but is acidic and needs lime.Cation exchange capacity (CEC) is a medium's ability to hold positively charged nutrients such as calcium, magnesium and potassium on its surfaces and release them later.Coco coir is a growing medium made from processed coconut husk, prized for holding water and air at once; it binds calcium and magnesium unless buffered.A micronutrient is an essential element plants need only in trace amounts, below a few mg/L: iron, manganese, zinc, copper, boron, molybdenum, chlorine and nickel.Medical and adult-use cannabis are separate legal channels: medical access depends on authorisation by a health professional, adult-use on age alone.pH measures how acidic or alkaline a solution is on a 0–14 scale; in growing it controls nutrient uptake, with soil best near 6.0–7.0 and hydro 5.5–6.5.Fulvic acid is the small, soluble fraction of humic substances that stays dissolved at any pH and binds metal ions; its benefit in cannabis is largely unproven.Compost tea is a liquid made by steeping compost or worm castings in water, often aerated with food sources, to extract and multiply microbes for the root zone.A chelate is a metal ion held by an organic molecule at several points, keeping micronutrients such as iron, zinc and manganese dissolved and available across a wider pH range.An organic fertiliser supplies nutrients from plant, animal or mineral-rock sources that soil microbes must break down into ions before roots can absorb them.A biostimulant is a product claimed to improve plant growth, uptake or stress tolerance by means other than supplying nutrients, such as seaweed extract, humics, amino acids or microbes.
