Coco coir is the fibrous material from coconut husks, processed into fine pith (coco peat), fibre and chips. It holds a lot of water while still leaving plenty of air space, rewets easily, resists compaction and breaks down slowly. It carries a natural cation exchange capacity, holding potassium and sodium from processing.
In practice
Raw coco can carry salts from washing in brackish water; quality products are washed to low EC. Its exchange sites also tend to take up calcium and magnesium and release potassium and sodium, which is why coco is pre-treated ("buffered") with a calcium solution and why coco feeds carry more calcium and magnesium. Run it like hydro: feed with every watering at about pH 5.8-6.2, water to 10-20% runoff, and never let it dry completely. Coco rewards frequent fertigation; small pots fed several times a day perform strongly.
Don't confuse with
- Peat: also a fine organic medium, but more acidic and harder to rewet.
- Coco (food): coconut flesh and water; unrelated.
Myth check
Cal-Mag needs in coco come from its cation exchange, RO water and cultivar, not from LED lighting (GenetixBay: Myth). See buffering coco.
Air-filled porosity is the share of a container's volume that holds air rather than water after it has drained, a key factor in root oxygen and overwatering risk.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.Sodium (Na) is not essential for cannabis; it enters through water, softeners and some inputs, and at high levels causes salt stress and crowds out potassium and calcium.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.Watering to runoff means applying enough water or solution that some drains from the bottom of the container, typically 10-20% of the volume applied.Fertigation is delivering fertiliser dissolved in irrigation water, so plants are fed every time they are watered rather than through solid amendments.Cal-Mag is a supplement supplying calcium and magnesium, usually as nitrates; need depends on cultivar, water source (RO vs tap) and medium (coco), not on LED lighting.RO water is water stripped of most dissolved salts by reverse osmosis; it has near-zero EC and little buffering, so pH moves easily and Ca and Mg must be added.Buffering capacity is how strongly a water, solution or medium resists pH change when acid or base is added; high capacity means stable but hard-to-move pH.Drain-to-waste fertigation feeds each plant fresh nutrient solution and lets the runoff leave the system rather than returning it to the reservoir.High-frequency fertigation feeds small volumes of nutrient solution many times a day, keeping the root zone consistently moist and fed so small pots can produce large plants.Perlite is a light, white, puffed volcanic glass added to growing mixes to increase drainage and air space; it is chemically inert and holds no nutrients.
