An organic fertiliser is a nutrient source derived from living or once-living material, such as manures, composts, meals (blood, bone, fish, feather, kelp, seed), or from minimally processed mined minerals. Most of its nutrients are held in organic compounds that microbes mineralise into the same ions found in mineral feeds, so release depends on temperature, moisture and microbial activity.
In practice
Organic feeding suits soil and living-soil systems, where microbial life does the conversion. Release is slower and harder to measure, so EC readings mean little. Caplan, Dixon and Zheng found cannabis in coir responded well to a liquid organic fertiliser at the right rate; Massuela and colleagues compared organic and mineral fertiliser levels in flowering cannabis. In recirculating hydro, raw organics tend to clog lines and feed biofilm. Certification rules for "organic" differ by jurisdiction.
Don't confuse with
- Mineral (synthetic) fertiliser: soluble salts delivering ions directly.
- Living soil: a whole system, not a single product.
Myth check
Plants mostly don't care where the ions come from (GenetixBay house position). Organic feeding may bring slight flavonoid or terpene differences, but that is unproven. See organic vs mineral.
EC (electrical conductivity) measures how well a solution conducts electricity, a proxy for total dissolved salts; growers read it in mS/cm to gauge nutrient strength.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 mineral (synthetic) fertiliser supplies nutrients as soluble salts that dissolve straight into plant-available ions; chemically, the plant takes up the same ions as from organic sources.A recirculating (closed) system returns drained nutrient solution to the reservoir to be reused, saving water and nutrients but needing more monitoring and sanitation.Living soil is an organic growing medium managed to sustain an active soil food web, so microbes and invertebrates release nutrients and the soil is reused across cycles.Flavonoids are polyphenolic plant compounds, including flavones, flavonols and anthocyanins, that colour and protect plant tissue; cannabis contains common ones plus cannabis-specific cannflavins.Terpenes are volatile hydrocarbon compounds built from five-carbon isoprene units; in cannabis they are made in the trichome heads and are a major part of aroma and flavour.Molasses is a sugar-rich by-product of sugar refining added to soil feeds; its sugars feed soil microbes, not the plant, and do not sweeten buds.Humic acid is a large, dark organic fraction of decomposed matter that binds nutrients and may modestly aid root growth; effects in cannabis are small and inconsistent.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.The N-P-K ratio is the three numbers on a fertiliser label giving percent nitrogen, phosphate (P2O5) and potash (K2O) by weight, not elemental P and K.
