Fertilizers explained

Credit: Brand X Pictures/Home and Garden/Alison Miksch

The major difference between these products is the sources from which they are derived. Chemical fertilizers are produced from pure ionic (water-soluble) compounds such as calcium nitrate and magnesium sulphate (Epsom salts). Organic fertilizers are made from biological (animal- and plant-based) and fossilized sources. Hydro-organic fertilizers are often a combination of both.

Chemical fertilizers are useful in that they are completely water-soluble (easily absorbed), include only the elements plants require (no waste) and can be easily chosen for your specific plants and growing conditions.

Organic fertilizers offer the advantage of breaking down slowly in the soil, feeding plants over a longer period of time (nutrients must break down before being absorbed). They are also a food source for other soil organisms (earthworms, beneficial micro-organisms) and a source of other plant supplements such as amino acids and carbohydrates that can often contribute to plant flavour and aroma.

Hydro-organic fertilizers must be completely water soluble for them to work in a
hydroponic system. Their organic ingredients are already broken down to their water-
soluble form, and any components not easily available from organic sources (calcium, for one) are added from a chemical source. The advantage of hydro-organic fertilizers is that they are completely soluble and supply all the benefits of the other supplements from their organic source.