Potassium silicate is a salt of potassium and silicate, sold as a viscous liquid or soluble powder. Analysis varies by product, so read the label for SiO2 and K2O content. In water it forms silicic acid, the form roots absorb. Its solutions are strongly alkaline.
In practice
Add it to plain water first, stir, then add the other nutrients, then adjust pH. Adding it to a finished feed, or mixing it with concentrates, can make the silicate polymerise into a gel or precipitate, and it can drag calcium and micronutrients out with it. Expect it to raise pH noticeably; dose before the pH-down step. Typical use aims for tens of mg/L (ppm) of Si in the final solutionbeing reviewed. It also contributes potassium, which counts towards the feed's K total.
Don't confuse with
- Silica: silicon dioxide; the word is used loosely for any silicon supplement.
- Monosilicic acid products: stabilised silicic acid, a different formulation.
- Sodium silicate (water glass): brings sodium, unsuitable for cannabis.
Silica is silicon dioxide (SiO2); growers use the word loosely for any silicon supplement added to stiffen stems and improve stress tolerance.Silicon (Si) is a beneficial element, not strictly essential, that plants absorb as silicic acid and deposit in cell walls, stiffening tissue and aiding stress tolerance.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.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.Stabilisation is breeding a seed line over several generations, with selection each time, until it reliably reproduces the chosen traits from seed.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.Potassium (K) is a mobile macronutrient that controls water balance, stomata and enzyme activity; deficiency scorches the edges of older leaves.A stock solution is a concentrated nutrient mix, often 100x or 200x final strength, diluted into the reservoir; calcium and sulfate/phosphate stocks must stay separate.
