Fertilizer basics & 25 types to try

Is fertilizer and lawn food the same thing?

No, lawns and all plants producte their own food with the exception of the ghost pipe –a plant that does not photosynthesize.

What is fertilizer?

Fertilizers are products that must provide an analysis of nutrient composition. They supply nutrients plant require for growth.

What are the effects of fertilizers on plant growth?

Fertilizers will improve plant growth unless your soil has sufficient levels of nutrients. Some nutrients can be taken up by plants in excess leading to toxicity.

What is the best organic high-iron fertilizer?

In terms of plant availability: iron lignosulfonate. Although not OMRI listed, it is derived from iron & a bi-product of wood pulp.

Fertilizers contain essential nutrients that plants need to grow and thrive. When applied to the soil, fertilizers provide nutrients such as nitrogen, phosphorus, and potassium to plants in a readily available form. Fertilizer is not technically “lawn food,” as plants generate their own food through photosynthesis. Rather, fertilizer provides the nutrients necessary for plants to carry out the process of photosynthesis and growth.

How to read a fertilizer label

NPK stands for nitrogen (N), phosphorus (P), and potassium (K). These three macronutrients are essential for plant growth and are the primary ingredients in most fertilizers.

The ratio of these nutrients in a fertilizer is indicated by the NPK numbers listed on the package. For example, a fertilizer with an NPK rating of 10-10-10 contains 10% nitrogen, 10% phosphorus, and 10% potassium.

What are nutrients?

In addition to nitrogen, phosphorus, and potassium, there are 12 other essential elements that plants require for healthy growth and development.  These elements are considered to be “plant nutrients”. These include calcium, magnesium, sulfur, iron, manganese, zinc, copper, boron, molybdenum, chlorine, cobalt, and nickel. These elements play a variety of roles in plant growth, from supporting photosynthesis to regulating water balance and maintaining cell structure.

In addition to these essential elements, there are also conditionally essential elements that some plants may require in small quantities. These elements include silicon, sodium selenium, chromium, and vanadium. For example, grasses take up silicon to deposit in cell walls. In most temperate soils, micronutrients are found in abundance and do not need to be supplied unless indicated by a soil test.


Lawn Fertilizer

Lawn fertilizer is important because turfgrass has a high nutrient requirement to maintain a lush appearance. Fertilizing your lawn can also help your grass to withstand environmental stresses such as heat, drought and frost.

Nitrogen is the most important nutrient for turfgrass, and it is typically the nutrient that is deficient in lawns. Other essential nutrients include phosphorus, potassium, calcium, magnesium, sulfur, and iron. A balanced fertilizer provides all of these essential nutrients in the appropriate proportions.

According to Purdue University, the best NPK ratio for lawns is a 3-1-2 ratio of nitrogen, phosphorus, and potassium. This ratio is ideal for promoting healthy turfgrass growth and maintaining the lawn’s green color.

2 types of fertilizers: organic and synthetic.

Organic fertilizers are made from natural sources such as compost, manure, and bone meal. They release nutrients slowly over time as they decompose, which can help improve soil health and fertility. Synthetic fertilizers, on the other hand, are manufactured from petroleum or are mined and processed. They provide nutrients in a more immediately available form.

25 Organic fertilizers NPK

Organic Fertilizer Nitrogen (N) Phosphorus (P) Potassium (K) Cost
Alfalfa meal 2.5% 1.0% 1.5% $-$$
Amino acids N/A N/A N/A $$$
Basalt N/A N/A N/A $$
Bat guano (cave) 10.0% 3.0% 1.0% $$-$$$
Bat guano (sea) 8.0% 6.0% 1.0% $$$
Biosolids 5.0% 2.0% 1.5% $
Bokashi 0.5% 1.0% 1.0% $$
Chicken manure 1.5% 1.0% 0.5% $
Chilean nitrate 16.0% 0.0% 0.0% $$-$$$
Coffee grinds 2.0% 0.3% 0.6% $
Compost 0.5% 0.5% 0.5% $-$$
Compost tea 0.5% 0.5% 0.5% $$-$$$
Corn gluten 10.0% 0.5% 0.0% $$$
Corn steep liquor 3.0% 0.5% 0.5% $$$
Crab meal 5.0% 3.0% 0.0% $$$
Feather meal 12.0% 0.0% 0.0% $$-$$$
Fish emulsion 5.0% 2.0% 2.0% $$-$$$
Grass clippings 2.0% 1.0% 1.0% $
Hoof meal 13.0% 0.0% 0.0% $$-$$$
Penicillin production by-product 3.0% 1.0% 1.0% $$$
Seaweed 1.0% 0.0% 4.0% $-$$
Soldier fly frass 3.0% 1.0% 2.0% $$
Soy meal 6.0% 1.0% 2.0% $$-$$$
Vinasse 0.6% 2.0% 0.6% $$
Worm castings 1.0% 0.5% 0.5% $$-$$$

The main differences between organic and synthetic fertilizers are release rate and organic matter content. Organic fertilizers release nutrients more slowly and also improve soil structure and water retention by increasing organic matter content. Synthetic fertilizers are more immediately available to plants but do not improve soil health to the same extent as organic fertilizers.

Fertilizer myths

There are many common fertilizer myths that are used in marketing to sell products. For example, some companies may claim their fertilizer can “break up clay” or “improve soil structure,” but this is not possible with fertilizer alone. Fertilizers can provide nutrients to plants, but they cannot physically alter the properties of the soil.

Another common marketing claim is “contains 70+ trace minerals” or a derivative of that. Plants don’t require these minerals for growth, there is 17 essential elements, but there are no essential minerals.


Fertilizers are essential for maintaining healthy lawns, it’s important to apply the appropriate amount of fertilizer for the type of grass you are growing. NPK ratios, essential nutrients, and nutrient release rates are all factors to consider when choosing a fertilizer. Organic and synthetic fertilizers have different benefits and drawbacks, and it’s important to understand these differences before making a decision. Finally, it’s important to be aware of common fertilizer myths and marketing claims that may not be supported by scientific evidence.

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