Contrary to the name, Epsom Salt is not salt, but rather a mineral compound of magnesium, oxygen, and sulphate (MgSO4), which exists naturally in water and springs. Epsom Salt is a white, powdered crystal, and is similar to table to salt in its appearance.
Epsom Salt is different from commercial fertilizers in that it is not persistent, and therefore will not build-up in the soil, nor affect the PH levels of the soil.
Importance of Magnesium in Epsom Salt
Epsom Salt is a natural and healthy source of magnesium. The presence of magnesium (Mg) in plants is essential in aiding the process of photosynthesis, the process whereby plants convert sunlight into food.
Magnesium (Mg) is important for maintaining the strength of plant cell walls, and the uptake of nitrogen (N), phosphorous (P), and potassium (K) is facilitated by the presence of magnesium.
When your cannabis plant is suffering from a magnesium deficiency, the leaves tend to yellow, starting at the lower sections of the plant, and resulting in a slightly curled leaf. (NOTE: if the leaves and the vein of your plant start to yellow, then it is suffering from a nitrogen deficiency).
Here at Just Cannabis, we use Epsom Salt as a source of magnesium rather than other soil amendments (such as dolomitic lime, for example), because Epsom Salt is highly-soluble, making it easier to apply. The PH levels of Epsom Salt solutions are closer to neutral, in contrast with the high alkalinity of magnesium salts found in limestone.
Thus, to achieve higher yields and bigger buds, magnesium is a key ingredient, and Epsom Salt is the best source.