Cannabis will grow in almost any soil, but it flourishes when the pH is between 6.5 and 7.0. Commercial potting soil almost never has a pH above 7.5. A lower pH is more common, even as low as 5.5. Some potting soils purchased at a nursery are pH balanced and near a neutral 7. However, most potting soils have a tendency to be acidic. The easiest way to stabilize soil pH is to mix in 1 cup of Fine Dolomite Lime per cubic foot (28 litres) of potting soil. Mix Dolomite Lime thoroughly into dry soil. Remix the soil in the container after it has been watered.
Fine Dolomite Lime has long been a favourite pH stabilizer for gardens. It is difficult to apply too much as long as it is thoroughly mixed into the soil. Dolomite has a neutral pH of 7, and can never raise the pH above 7. It stabilizes the pH safely.
Compensate for acidic soil by mixing dolomite with soil before planting. Dolomite is a compound of Mg (Magnesium) and Ca (Calcium). Dolomite does not prevent toxic salt build-up caused by impure water and fertilizer build-up. Proper fertilizer and regular leaching (To remove soluble or other constituents from by the action of running water through the medium (soil makeup)) helps flush away toxic salts. When purchasing look for Dolomite Flour, the finest fast-acting dust-like grade available. Coarse Dolomite could take a year or more before it becomes available for uptake by roots. Improperly mixed dolomite will stratify, forming a cake or layer that burns roots and repels water.