How to Choose the Right Fertilizer

Article written by Troy-Bilt brand ambassador Noelle Johnson of AZ Plant Lady 
When reading the label on a package of fertilizer, you may have a few questions, such as what does NPK mean, what do the three numbers indicate, and how can you tell which type of fertilizer is right for your garden? Let's take the mystery out of fertilizer so that next time you find yourself in the fertilizer aisle of your local nursery or big box store, you'll be able to find the best one to suit the needs of your plants.


First, let's talk about NPK and what it means. These three letters are an abbreviation for nitrogen, phosphorus and potassium, which are the three major nutrients that plants need. Of these three, nitrogen is the most important nutrient and is vital for plant growth and lush green color. Lawn fertilizers are typically high in nitrogen. The second nutrient, phosphorus, promotes flowering, fruit and seed development. Super-Bloom used to increase flowering, are high in phosphorus. The last major nutrient is potassium, which is vital for root formation, as well as promoting growth in the upper parts of plants. 
Nutrient deficiencies occur when plants don't have enough of a particular element. Nitrogen is the one that plants are likely to be deficient in as it is easily leached away by excess water. Signs of nitrogen deficiency begin to show up when older leaves begin to yellow. Plants that are low in phosphorus can have leaves that are reddish-purple in color or look as if they have been burned. If potassium levels are low, the edges of leaves can look brown and crispy.
Most fertilizers contain one or more of these major nutrients, which are indicated on the label by three numbers separated by dashes. The amount of nitrogen, phosphorus and potassium are measured by percentages and differs between each type of fertilizer. A balanced fertilizer contains all three nutrients in equal proportions and is suitable for the needs of most plants. An incomplete fertilizer is a good choice to correct a specific nutrient deficiency as it will provide that particular nutrient. Fertilizers created for individual types of plants are called special-purpose fertilizers, and examples include those formulated specifically for citrus trees, roses, orchids, and lawns. Finally, slow-release fertilizers are an increasingly popular fertilizer choice as they release nutrients over a 3 to 6-month period. 
There are two different classifications of fertilizer; organic and synthetic, and both are sources for all the major nutrients. Organic fertilizers are derived from natural sources such as animals and plants. They slowly release nutrients while also benefitting the soil. They do this by improving drainage, fertility and increasing the number of beneficial microorganisms within the soil. Cow, chicken and rabbit manures are examples of organic fertilizers as are blood and bone meal. Synthetic fertilizers are created from chemicals and act quickly to correct nutrient deficiencies. Ammonium nitrate and super phosphate are types of synthetic fertilizers. Their effects are short-lived, and often need to be reapplied. Unlike fertilizers that are organic, they don't improve the soil, kill beneficial soil microorganisms and can pollute nearby water sources, so whenever possible, it's best to choose organic fertilizers. 
Fertilizers are a great tool in helping care for the plants in your garden. Now that you know how to choose the right one, you can walk down the fertilizer aisle with confidence.