The numbers on a fertilizer bag are the so-called N-P-K ratio, the percent of nitrogen, phosphorus, and potash (or potassium, chemical symbol K) inside the bag. Simply speaking, nitrogen is for green growth; phosphorus is for roots, flowers, and fruit; potash is for general vigor and disease resistance. A so-called balanced fertilizer, often recommended in books, is one that has equal percentages of each element.
With chemical fertilizers, the numbers are much higher than with organic formulations. A standard is 10-10-10 or 5-10-5, meaning there are those percentages of each element in the bag (the rest is filler). You won’t find those totals in any organic formulation. In fact, if the total of the three numbers on a so-called organic or natural bag adds up to more than 15, I’m suspicious. Unless blood meal—an organic material very high in nitrogen—is in the ingredient list, I suspect that the formula has a chemical booster in it.
Labels can be confusing, since many companies have put flowers and butterflies on their bags but still have chemicals inside. Learn to read what’s inside; the more plain-English words you see on the ingredient list, the better. Typical nonchemical ingredients are dried animal manures, rock dusts, bonemeal, alfalfa meal and other meals, and dried blood.
All-natural,
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