Beginning Gardeners Series: May

  • Difficulty Rating: Beginner
may fertilizers

When it comes time for a beginning gardener to choose the right fertilizer to purchase for use with plants, the options can be overwhelming.

In addition to the vast number of options available, there are those 3 big numbers on the front of all of the containers. How do you decipher their meaning and compare them? And then there is the battle of organic vs. chemical (or inorganic) vying for your loyalty and your dollar.

We'll begin with the numbers on the front of the containers, because a basic understanding of what they represent can often narrow down the selection and help you choose one fairly quickly. The numbers represent the percentage, by weight, of nitrogen, phosphorus, and potassium (or NPK) in the container, and they are always in the same order regardless of the brand. What is it about those numbers that earns them such a prominent display on the front of all of those containers?

  • Nitrogen aids in the growth of leaves.
  • Phosphorus is needed for the roots, fruit, and flowers.
  • Potassium is needed for production of chlorophyll, is good for the overall health of plants, and helps with disease resistance.

In regards to the battle between organic and inorganic, I'll begin by explaining what each of these terms means. Organic fertilizers are made up of natural materials from plants and animals such as manures, plant waste, and blood meal, as well as some minerals. Inorganic fertilizers are made from minerals or from synthetic chemicals. Take a look at the photo above and notice the difference in appearance between these organic and inorganic fertilizers. The organic is on the left and it looks like dirt! It also smells earthy. The inorganic on the right has a mineral appearance and has a chemical smell to it.

In recent years, inorganic fertilizers (and pesticides, as well) have been maligned by many as always being the wrong choice. There are some situations where inorganic is a better choice, but generally organic options are recommended when available. Organic fertilizers, while not as quickly available to plants because they are not as concentrated and must first be broken down by microorganisms in the soil, do improve the health of soil over time. Inorganic fertilizers not only don't improve the soil, they have been found to cause the microorganisms to disappear over time.

As experience is gained with gardening, eventually you may also find that you can make your own organic fertilizers at home very inexpensively and possibly even at no cost. Manures from cows, chickens, rabbits, and a variety of other animals make excellent organic fertilizer, as does composted kitchen and garden debris.