Is 15-15-15 Fertilizer Good for Lawns? (When to Use)

It’s that time of the year when your lawn requires a nutritional boost, but you are not sure about the NPK fertilizer ratio to use. So, is 15-15-15 fertilizer good for lawns?

A 15-15-15 fertilizer is not the best choice for lawns. This fertilizer contains high percentages of phosphorus and potassium. Excess potassium can inhibit the plants’ absorption of nitrogen and other nutrients from the soil.

Is 15-15-15 Fertilizer Good for Lawns?

Fertilizer containing an NPK ratio of 15-15-15 is not ideal for lawns. The high amount of potassium may inhibit the absorption of nitrogen and other nutrients. The fertilizer also contains a high amount of phosphorus, which is unsuitable for an already established lawn.

Established lawn and new lawn requires different NPK fertilizer ratios. An established lawn thrives well on a fertilizer containing a high amount of nitrogen, no phosphorus, and little amount of potassium.

On the other hand, a new lawn will require fertilizer containing equal amounts of nitrogen and phosphorus with little potassium.

Nitrogen promotes lush green growth in plants. It increases the production of chlorophyll molecules that absorb more energy from the sun for photosynthesis. Phosphorus is the second primary element required by your lawn to develop stems and a strong root system.

Potassium is the last element that helps plants resist drought and diseases. 32-0-4 is an example of the best fertilizer ratio for lawns. This fertilizer contains 32% nitrogen, 0% phosphorus, and 4% potassium. These ratios may vary depending on the growth stage of your lawn.

New or struggling lawns require a fertilizer containing a high amount of nitrogen and phosphorus with a small amount of potassium. 22-23-4 is an example of a fertilizer that will stimulate green growth and better root development.

There’re also alternatives to chemical fertilizers that are best for your lawn. Organic fertilizers help improve the health of plants without contaminating the soil and water. Mulching leaves and grass clippings naturally add nitrogen to the soil when the plant materials decompose.

Other organic fertilizers that you can use on your lawn include:

  • Coffee grounds to improve the Nitrogen content
  • Blood meal to treat phosphorus deficiency
  • Fish emulsion
  • Bone meal and
  • Worm castings.

Organic fertilizers may take longer to decompose before releasing nutrients into the soil, so be patient when using them.

What is Triple 15 Fertilizer Good for?

Balanced fertilizers are great for most garden crops but not ideal for trees and lawns. A 15-15-15 fertilizer ratio is good for almost all vegetables, fruits, and ornamental flowers. They require a balanced fertilizer to flourish and flower.

This is a multi-purpose fertilizer that helps strengthen the roots, promotes a deep green color, and strengthens the plants against diseases and tough weather conditions.

Fertilizing ornamental flowers with triple 15 fertilizer helps to strengthen all parts, including the roots, stems, and petals. Therefore, you are guaranteed beautiful flowers that blossom in abundance.

Triple 15 fertilizer contains an equal amount of nitrogen, phosphorus, and potassium. The balanced primary elements can perfectly fit most plants in your garden. Each of these elements benefits the plants in different as explained below:


Nitrogen is essential to plants in different ways:

  • It helps to promote the growth of different plant tissues, such as leaves and trunks.
  • It helps plants to produce chlorophyll. Have you ever wondered why plants are green? Chlorophyll molecules give the plants green pigmentation.
  • Prevents discoloration of leaves. Nitrogen promotes lush green growth. The yellowing of leaves characterizes its deficiency.
  • Assists with photosynthesis. This is a process in which plants use sunlight, carbon dioxide, and water to form sugars and starch. Nitrogen is part of chlorophyll that plays an important role in this process.
  • Strengthens the plants’ DNA. Nitrogen helps in retaining the genetic code within the plant’s nucleus.


Phosphorus is the second primary element required by plants. It is beneficial to plants in different ways, as explained below:

  • Phosphorus encourages root growth in any plant. As we know, roots are the foundation of plants, and having a web-like root system promotes the healthy growth of the entire plant.
  • It improves flower formation and seed production. Flowers formation is an indication of a healthy fruit set. Vibrant blossoms on ornamental plants are also important to gardeners.
  • It also improves plants’ resilience against harsh winter weather conditions.


Potassium is the third element required by plants. It helps plants in different ways.

  • Improves drought and disease resistance as well as promotes root growth.
  • It helps plants to produce energy through the process of photosynthesis.
  • Enhances movement of starch and sugars within the plant.
  • Increases production of plant proteins.
  • It prevents energy loss by reducing the rate of respiration.
  • Maintains turgidity in plants by reducing wilting and water loss.
  • Enhances the production of grains rich in starch
  • Aids in building cellulose as well reducing lodging within the plant tissues.

Fertilize your plants with a 15-15-15 fertilizer when they are at the peak of their growth cycle or when they are actively growing. Early spring is the best time to fertilize as it helps plants recover quickly from tough winter conditions.

Before fertilizing your plants, be sure to read and understand the user instructions. Use the manufacturer’s instructions to find out everything you need to know about the fertilizer, such as the application rate and method to use.

Generally, the standard fertilizer application rate is 1 pound per 1,000 square feet of land. Excess application may weaken plants and pollute rivers, ponds, and other water bodies downstream.

Also Read: Is 10-10-10 Fertilizer Good for Lawns?

Final Thoughts

As stated earlier, the ideal fertilizer ratio on an established lawn should have high nitrogen content, no phosphorus, and little potassium. On the other hand, a new lawn requires a fertilizer containing a high amount of nitrogen and phosphorus with little potassium.

15-15-15 fertilizer contains high amounts of nitrogen, phosphorus, and potassium. This ratio is not ideal for both new and established lawns. However, it is good for vegetables, fruits, and ornamental flowers.


  1. Clemson University Cooperative Extension: FERTILIZING LAWNS
  2. University of Massachusetts Amherst: Fertilizing Guidelines
  3. New Jersey Agricultural Experiment Station: How to Calculate the Amount of Fertilizer Needed for Your Lawn

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