Lawn fertilization is a difficult process because you cannot see each of the nutrients that your lawn needs. However, lawns often exhibit characteristics when they are not receiving proper nutrition. This is why proper fertilizer and fertilization procedures are essential in maintaining a lush, healthy lawn. In this article, you can learn about the types of lawn fertilizer, how to apply it, and signs to look for in your lawn.
What is lawn fertilizer made of?
Lawn fertilizers contribute three primary nutrients, nitrogen, phosphorous, and potassium, to soil to stimulate plant growth. The amount of these three macronutrients, commonly referred to as NPK, grace the label of all fertilizer bags where required by law. Each of these nutrients contribute its own benefit to plant growth. First, nitrogen primarily benefits the speed of leaf growth. Fertilizers high in nitrogen are excellent for plants like grass that require growth more than flowering. Phosphorous specializes in root growth, making it an essential nutrient for all plants. Finally, potassium, delivered in the form of potash, strengthens plants and helps them resist diseases. You can find the percentage of each of these nutrients on the label of the fertilizer you choose. For example, 20-20-20 means the fertilizer contains 20% nitrogen, 20% phosphorous, and 20% potassium. The rest of the fertilizer is often comprised of many micronutrients, such as zinc, magnesium, copper, iron, and others.
Types of lawn fertilizers
There are many types of lawn fertilizers, and each of these types contain subcategories that specialize in specific lawn needs. The two major types of lawn fertilizers are organic and synthetic, but we will also address two common subtypes of fertilizer, liquid and granular.
Organic fertilizers
Organic fertilizers, also known as natural fertilizers, are made from naturally occurring materials like animals and plants. Materials used in organic fertilizers include manure, bone meal, compost, seaweed, and many others. Because they are natural, organic fertilizers contain a smaller concentration of nutrients than synthetic fertilizers. As a result, the results of organic fertilizer take longer to show, but they also provide nutrients to plants for longer than synthetic fertilizers. This longevity is due to the biodiversity organic fertilizers contribute to soil.
Pros of organic fertilizers
- Provide environmentally friendly nutrition
- Less likely to burn plants if applied incorrectly
- Create a healthy microbial environment
- Provide a sustainable solution
Cons of organic fertilizers
- Provide nutrients slower than synthetic fertilizers
- Can attract pests
- Often contain less concentrated nutrients than synthetic fertilizers
- More expensive than synthetic fertilizers
Synthetic fertilizers
Synthetic fertilizers, unlike organic fertilizers, are made from chemicals that address nutritional needs in plants. These fertilizers contain the three primary nutrients, nitrogen, phosphorous, and potassium, alongside micronutrients and secondary nutrients. The percentage of these nutrients varies by the type of fertilizer, and the variation in these nutrients allows you to target specific nutrient needs in your lawn or other plants. Synthetic fertilizers come in many variations, including liquid fertilizers and granular fertilizers listed below.
Pros of synthetic fertilizers
- Efficiently provide nutrients
- Less expensive than organic fertilizers
- Cater to specific nutritional needs
Cons of synthetic fertilizers
- Can destroy soil composition over time
- Do not contribute to microbiome like organic fertilizers
- Less environmentally friendly
- Can harm human health if used incorrectly
Liquid fertilizers
Liquid fertilizers are nutrient formulas that mix with water to form a solution. These synthetic fertilizers are applied to lawns with either a manual sprayer, sprinkler, or irrigation system. Liquid fertilizers provide quick nutrition to plants and grass across entire lawns or small targeted areas. They are the easiest type of fertilizer to apply evenly across a large area, and the spreading can be automated with a feeder, such as the Green Feeder system by American Hydro, in a home irrigation system. However, because they are a solution, liquid fertilizers are the most likely type to be washed away by rain.
Pros of liquid fertilizers
- Can be applied evenly
- Provide quick nutrition
- Can be used for both large lawns or small targeted areas
- Can be used with home irrigation systems
Cons of liquid fertilizers
- Are most likely type to be washed away
- Must be applied more frequently than other types
- Contain more consistent nutrient concentration than other types
Granular fertilizers
Granular fertilizers are solid granules that slowly release nutrients into soil as they dissolve. Granular fertilizers are best distributed by a spreader to ensure that the granules are spread evenly across the lawn. Granules come in both quick-release and slow-release formulas, allowing you to provide a surge of nutrients to your lawn or to supply the nutrients slowly over a longer period. If you own a fertilizer spreader, applying granular fertilizers is easy and you do not need to apply them as often as liquid fertilizers.
Pros of granular fertilizers
- Can be applied less often than liquid fertilizers
- Easy to use with spreaders
- Available in both quick-release and slow-release formulas
- Less likely to be washed away by rain
Cons of granular fertilizers
- Do not work as quickly as liquid fertilizers
- Can attracts pests
- More difficult to apply than liquid fertilizers
- Can burn plants if applied incorrectly
10 steps to fertilizing your lawn
Regardless of the type of fertilizer you use, you can properly fertilize your lawn by following the steps below.
1. Determine the appropriate amount of fertilizer
In general, lawns need between .75 and 1 pound of nitrogen per 1000 square feet. As a result, the amount of fertilizer you need for your lawn depends on the concentration of nitrogen in your fertilizer. Certain fertilizers recommend a different amount of nitrogen per 1000 square feet than others. Follow the guideline set by the fertilizer manufacturer to ensure proper fertilization of your lawn. Avoid overfertilizing, as this can cause side effects like brown grass and black roots.
2. Test your soil
Testing your soil provides you with knowledge of what nutrients your lawn needs. You can test your lawn’s soil by a professional test by an extension service or with a home lawn test kit. While home lawn test kits are convenient, they are far less reliable than extension tests that are provided by universities at low costs. You can find the closest available extension tester to you here.
3. Choose the appropriate fertilizer
Based on the results of your soil test, you should know the nutrients your soil needs more and less of. Now you must choose the type of fertilizer you use as well as its nutrient content. Fertilizers come in a variety of types, each of which possesses its own positives and negatives. Consequently, you should choose the fertilizer type that best suits your lawn and home. If you want an environmentally-friendly fertilizer, for example, organic fertilizers are your best option. On the other hand, liquid fertilizers are the most convenient if you have a home irrigation system.
Once you have selected the appropriate type of fertilizer, you must ensure that the fertilizer meets the nutritional demands of your lawn. Now is when you must pay attention to the NPK number in the fertilizer you choose. This number will be present on all fertilizer products in the form of three numbers separated by dashes. For example, the GrassSoGreen Maintenance Formula by American Hydro contains an NPK of 19-0-0. This means it is composed of 19% nitrogen, 0% phosphorus, and 0% potassium. If your soil test reveals that you needs more potassium or phosphorus, choose a fertilizer accordingly. Some states do not allow fertilizers with phosphorous, so ensure that the fertilizer you choose is allowed in your state if you order online.
4. Choose the best application time
Late spring is typically the ideal time to fertilize cool-season grasses, while summer is ideal for warm-season grasses. Pay attention to the weather around the time you plan to apply fertilizer. Avoid fertilizing your lawn in times of drought, rainfall, or extreme cold or hot temperatures.
5. Prepare your lawn
Before applying fertilizer, you should mow your lawn and remove any debris. At this stage, continue your normal watering schedule and adjust the pH of your soil if needed. Most grass types thrive with a pH between 6.5 and 7.
Learn more: A guide to watering your lawn
6. Read fertilizer instructions
To fertilize the appropriate amount, you must follow the application rate instructions provided by the fertilizer manufacturer. For granular fertilizers, for example, you must adjust the application rate of your spreader to apply the fertilizer correctly. Carefully read all instructions and warnings on your fertilizer before applying. If the fertilizer is toxic to humans, ensure you wear the appropriate protective gear like gloves and eye protection.
7. Apply fertilizer
Now that you have prepared by selecting the appropriate fertilizer for your lawn, it is time to apply it. The application process is different for each fertilizer type. For example, liquid fertilizers must be applied with a sprayer or irrigation system, while granules are best applied with a spreader. Regardless of the type of fertilizer you use, strictly follow the fertilizer’s application guidelines for the best results.
8. Follow fertilizer post-application instructions
Some types of fertilizers require certain tasks to be completed immediately after they are applied. For example, granular fertilizers must be watered down to dissolve nutrients and to prevent the granules from damaging the grass.
9. Practice a maintenance routine
After fertilizing, ensure you continue to follow proper mowing, watering, aeration, and further fertilization procedures to maintain a lush lawn. Below are the common timelines for each maintenance task.
- Mowing: Once per week (peak growing season) or twice per week (rest of season)
- Watering: Twice per week for 30 minutes each (1 to 1.5 inches of water per week including rainfall)
- Aerating: Once per year (early spring or fall for cool-season grasses and late spring or early summer for warm-season grasses)
- Fertilizing: Varies by fertilization method (follow fertilizer instructions)
10. Monitor your lawn’s health
Throughout the year, monitor the health of your lawn by looking for signs of unhealthy grass. Symptoms like yellowing or browning, excessive growth, strange odors, and patchy grass can signal problems with your soil’s chemical balance. Periodically test your soil to ensure that it is healthy and balanced.
Signs of lawn overfertilization
While fertilizer provides many benefits to soil, there can be too much of a good thing. Overfertilizing is a common lawncare mistake that shows consistent symptoms. The following are common signs of overfertilization in a lawn:
- Excessive or slow growth. While this may sound counterintuitive, too much growth in your lawn is not a sign of health. Grass that grows too fast is weaker and more susceptible to disease than grass that grows at the proper rate. Slow growth is also a sign of overfertilization.
- Yellowing or browning. When grass attempts to absorb more nutrients than it needs, it can die, causing it to turn yellow or brown.
- Patchy grass. Patchy grass is a sign of nutritional imbalance in a lawn. This is because some areas of the lawn are receiving more nutrients than others, causing some patches to thrive and others to die.
- Runoff. Too much fertilizer can cause fertilizer runoff. Signs of runoff include yellowing or browning, foul odors, and unusual properties in nearby bodies of water.
- Burning. Burning is a common sign of overfertilization. It occurs when the excess salt content of too much fertilizer damages the root system. When grass “burns”, it exhibits a brown or yellow color in patches or streaks.