I bet you thought fertilizing your garden was pretty basic – just dump a bunch around the plants and water it in. Unfortunately, it isn't that simple and shouldn't be done that way for a variety of reasons.
But first: Do your plants really need fertilizer?
Many plant problems cannot be solved with fertilizer – pay attention to your soil first – add organic material like compost regularly to improve soil tilth, drainage, and nutrition.
There are 18 essential nutrients that plants require to grow and survive. Carbon, Hydrogen, and Oxygen are needed in the greatest quantity and are obtained from air and water. The next 6 nutrients are considered macronutrients;…Nitrogen, Phosphorus, and Potassium…. Calcium, Magnesium, and Sulfur. The remaining 9 elements are considered micronutrients and include Chloride, Iron, Boron, Manganese, Zinc, Copper, Molybdenum, Nickel, and Cobalt… Each of these play an important role in the different structures and functions of the plant… [and] if one essential nutrient is deficient, plant growth will be poor even when all other essential nutrients are abundant. These nutrients primarily come from the soil; however, when the soil's nutrient reserves become low, nutrients can be supplemented through the addition of… fertilizer, compost, and manure.
Starting a Garden: Fertilization, College of Agricultural, Consumer & Environmental Science, Illinois Extension
As we stress time and again, never fertilize your garden without doing a soil test first. In most soils, especially where compost is added regularly, there is enough fertility to grow the majority of plants. If soil is cared for correctly in the perennial garden where roots run deep, fertilizer will rarely be necessary (I can't remember the last time I fertilized my flower beds).
