Fertilizer is full of nutrients that break down and soak into the soil where plants and grass can use them to become stronger and healthier. When host Kevin O’Connor wanted to learn more about fertilizer, he turned to landscape contractors Jenn Nawada and Lee Gilliam for a lesson at the shop.
What is Fertilizer?
Fertilizer is a soil additive designed to help plants grow bigger, stronger, and healthier by replenishing nutrients in the soil. Each fertilizer type is fine-tuned to a specific soil type, ensuring customers can choose the product that best fits their plants’ needs.
Types of Fertilizer
Fertilizer comes in two specific kinds: organic and synthetic. Organic fertilizers come from natural materials like compost, manure, and bone meal. There are even products made from human waste. Synthetic fertilizers are designed and created in laboratories.
Each Bag Shows the Nutrient Ratio
Each bag of fertilizer has a rating indicating its NPK (nitrogen, phosphorus, and potassium) content. Those ratings indicate how much of the content in the bag is composed of those specific nutrients. An NPK rating of 10-10-10 describes a fertilizer that contains 10% nitrogen, 10% phosphorus, and 10% potassium.
- Nitrogen: Good for stems, leafy growth, and lush green lawns
- Phosphorus: Good for root growth, blooming, and fruiting
- Potassium: Good for plant strength and resisting diseases
Potency by Type
NPK ratings describe the content of individual mixes but don’t fully account for potency. A general rule is that synthetic fertilizers offer a quick punch with a faster reaction time than organic fertilizers, which need time to break down into the soil.
So, Which is Right for You?
It’s helpful to think of fertilizers like this: organic fertilizers are the multivitamins to help you stay healthy, while synthetic fertilizers are the antibiotics that work quickly when you’re sick. That’s not to say you need to choose one or the other, but it’s a good idea to focus primarily on organic fertilizer and supplement with synthetic fertilizer when needed. But it’s important to know which types of plants you have and what their needs might be.
Applying Fertilizer
Applying fertilizer requires some specific knowledge. First, applying too little fertilizer won’t help the plants, but applying too much can actually burn them. It’s best to follow the ratio on the bag.
Also, some regulations determine how close you can use fertilizer to bodies of water, as too much fertilizer can run off in rain and leach into the water, causing harmful conditions like contaminated water and algae blooms.
Choosing Between Synthetic and Organic Fertilizers
You can choose either synthetic or organic fertilizer options. Synthetic fertilizers are manufactured chemical products that provide precise nutrient ratios, while organic fertilizers are made of natural materials such as compost, bone meal, and fish emulsion. Both have their pros and cons, which you can read more about below.
| Type | Pros | Cons |
|---|---|---|
| Synthetic | Consistent and predictable results Higher nutrient concentrations More affordable Quick-acting | Can harm beneficial soil microbes if you overuse it May lead to nutrient runoff if you don’t apply it correctly |
| Organic | Environmentally friendly and sustainable Improves soil structure and promotes beneficial microbes Often contains trace minerals that benefit plant health Releases nutrients slowly, and reduces the risk of over-fertilization | Lower nutrient ratio, which helps some plants but hurts others More expensive than other types Slower and less consistent results |
How to Read Your Soil Test Results
Once you have your soil test report, you can convert its recommendations into the NPK ratio you need. Divide the weight of each recommended nutrient (N, P, and K) by the nutrient with the lowest weight. For example, if your report calls for 1.5 pounds of nitrogen, 0.5 pound of phosphorus, and 1 pound of potassium, divide each by 0.5. The result is a 3-1-2 ratio — so you’d look for a fertilizer label that closely matches, such as 9-3-6.
