From year to year, the cost of fertilizer can fluctuate, and occasionally, a certain analysis or brand of fertilizer may not even be available. Why all the changes? When you consider the raw materials that make up a typical fertilizer blend, where these materials originate and how they are processed, it becomes quite apparent. The cost and supply of fertilizers designed for greenhouse and nursery use are intertwined with a number of variables, including geography, global markets, politics, transportation logistics and energy costs.
If you look at the guaranteed analysis “derived from” statement on a bag of blended fertilizer, you will see that fertilizers (especially complete blends containing N-P-K, Ca, Mg, S and micronutrients) can easily contain a dozen or more components (see photo above). Even if your fertilizer source is a blender, there may be other components in the product that are not listed on the label. The complexity of ingredients in fertilizer blends is particularly apparent when you look at a blended granular product (Figure 1, page 36).
