The weather in Canada is finally getting a little warmer, and spring is just around the corner. This is the perfect time to learn more about lawn fertilizer numbers to prepare your grass for the next season.

A lush lawn is incomplete without the right fertilizer, as it adds nutrients your soil needs after a dormant winter. So, if you want to keep your lawn lush this spring, you have come to the right place.

Our lawn care experts have created a comprehensive guide to fertilizer numbers for lawns you need to know this season.

What are Lawn Fertilizer Numbers?

The meaning of lawn fertilizer numbers explained

As you choose between fertilizers, you will notice that every label has a three-number combination. These numbers are known as the NPK ratio.

This ratio is one of the most important factors in choosing the right fertilizer for spring and your grass. These numbers can look like 10-8-8, 21-0-7, and much more.

NPK stands for nitrogen, phosphorus, and Potassium. The potassium and phosphorus content will always be lower than nitrogen for a lush lawn.

However, the only way to understand your specific lawn needs is to conduct a soil test that will determine the nutrient requirements of your lawn.

You can damage your lawn through overfertilization if you don’t do this.

Fertilizer Numbers for Lawn: The Role of Each Nutrient in the NPK Ratio

An infographic explaining each letter in the NPK fertilizer ratio

Lawn fertilizer numbers are important because they affect the health of your lawn. Nitrogen is perhaps the most important nutrient you must add frequently to your lawn.

However, each nutrient in the NPK ratio has a special part to play in lawn health.

1. The Role of Nitrogen

Nitrogen is important because it promotes the rich green colour of your lush lawn and optimal leaf growth. Without this important nutrient, your lawn can look yellow, dull, and lifeless.

In the long run, adequate nitrogen content in your lawn will help it to grow in the best way possible. It stimulates the growth of new roots, which is why lawn fertilizers for spring will have a high nitrogen level to help your grass grow during spring.

When spring is near, applying nitrogen-rich fertilizer can help your lawn have a rich growing season for the rest of the year. It is also important to have the right lawn care schedule all year round.

2. The Role of Phosphorus

The second number in the NPK ratio is phosphorus, which is crucial in creating and strengthening a healthy grass root. These strong roots are ideal for withstanding any environmental distress.

Even when the seasons change, healthy roots, with the help of phosphorus, will ensure a beautiful lawn. It is one of the top lawn fertilizer numbers responsible for the metabolic processes.

These processes transfer energy throughout the plant. It will help the plant utilize energy more efficiently and grow optimally.

3. The Role of Potassium

The third number in the NPK ratio is Potassium. This nutrient is crucial for maintaining the overall health of the plant.

It is responsible for supporting the internal processes of plant cells that affect:

  • The production of protein
  • Respiration
  • Water absorption
  • And photosynthesis

If the plant or grass is weak in Potassium, it will be more susceptible to disease and injury. In the long run, Potassium will aid in disease resistance, cold hardiness, and tolerance to droughts.

What is the NPK Ratio for a Lawn: A Breakdown of the Numbers

The lawn fertilizer numbers in the ratio represent the percentage of the three nutrients by the fertilizer bag weight. For example, if the bag says 24-4-12, and the weight of the bag is fifty pounds, the nutrient content will be:

Twelve pounds of nitrogen, 2 pounds of phosphorus, and 6 pounds of Potassium.

The math is simple for this:

24/100 x 50 = 12 (for nitrogen). Applying this equation to other percentages will give you the above answer.

Yes, the ratio doesn’t amount to 100% because the bag contains other things to hold the nutrients together.

This amount will help you determine how much fertilizer to apply to your lawn. The general rule is to use no more than one pound of nitrogen for every 1,000 square feet of lawn at one time.

Remember that the higher the nitrogen content, the less fertilizer your lawn will need. This is why knowing fertilizer numbers for lawns is crucial.

Lawn Fertilizer Numbers: The Best One for Every Season in Canada

An infographic of the lawn fertilizer numbers for each season

Now that you have some basic information about lawn fertilizer numbers, it is crucial to understand the right ratios for each season. These general rules will help you apply the right amount of fertilizer to your lawn.

1. Lawn Fertilizer Numbers for Spring

We recommend that you use fertilizers with a high nitrogen content for spring. These will help your turf grow strong when you spread it during the early spring.

However, your ratio will be important to determine how well your lawn will grow. Some of the best spring lawn fertilizer numbers include the following:

  • 15-0-6
  • 35-0-5
  • 30-0-3
  • 20-0-5

For most lawns, the 20% nitrogen content will be the safest. Keeping this number the highest will ensure your lawn can make it through the change in season as the first warm day of the year hits.

Please note that most fertilizers will have 0 in the middle. The reason for this is that you will need to conduct a soil test to determine whether your lawn requires phosphorus.

2. Summer Fertilizer Numbers for Your Lawn

For summer, the ideal fertilizer ratios include the following:

  • 10-0-4
  • 15-0-8
  • 6-0-0

Such lawn fertilizer numbers will ensure your grass remains strong and healthy while avoiding fertilizer burns because of the heat. However, another factor to keep in mind is the type of grass on your lawn.

For example, if you have something like Kentucky Bluegrass on your lawn, you can’t fertilize it in the summer.

On the other hand, if you have St. Augustine or Bermudagrass, you can fertilize it in the summer.

As a general rule, we recommend using a mild summer fertilizer that will slowly release nitrogen. This will help the lawn remain resilient and reduce any possible burns.

3. Lawn Fertilizer Numbers for Fall

Fall is the time to let the warm-season grass be and fertilize your cool-season grasses instead. While using a high nitrogen is important in other seasons, it is crucial to use a low nitrogen ratio in fall.

After all, you don’t want nitrogen to hinder the natural plant processes when the temperature is too cold for any grass to grow.

Using a high nitrogen content in fall will lead to the plants being under stress, and there will be bare spots on your lawn.

Our lawn experts in Mississauga recommend you use 20-0-5 or 6-0-0 on your lawn. The 20 NPK ratio is common in stores during fall, but we recommend conducting a soil test before using this ratio.

Once you use the right ratio in fall, it will ensure that the grass is healthy enough to withstand the cold temperatures in the winter.

4. Winter Fertilizer Numbers

If you plan to use fertilizer in the winter, then the ideal lawn fertilizer numbers for winter include 1-0-1 or 1-0-0.5. The Potassium will promote root strength, while the small amount of nitrogen will help with growth.

Usually, it is best to leave your lawn alone during the winter time, as the fall fertilization will be more than enough. However, if you still want to add some nutrients, then you can stick to these winter fertilizer numbers.

5. Starter Fertilizer Numbers

Starter fertilizers are ideal for new grass or seedlings to grow. Because of this, their NPK ratio will have more phosphorus and less Potassium.

Starter fertilizer numbers should have at least 10% nitrogen, 20% or more phosphorus, and around 5% potassium.

So, for example, a 10-10-10 ratio is one of the most common lawn fertilizer numbers for starters. However, you can conduct a soil test and determine what levels of nutrients will be ideal for your soil.

Then, you can use different fertilizers and ratios to get the perfect NPK fertilizer ratio for your specific lawn in Canada.

When to Fertilize Lawn: Top Three Factors to Consider

An infographic on when to fertilize lawn

Before you decide the ideal time of when to fertilize lawns, you must consider three factors. These include the following:

  1. Weather: It is important for your lawn to be dry before you apply any type of fertilizer to it. Then, after you apply, you will have to water it in to ensure it works its magic.
  2. Temperature: You should fertilize your warm-season grass when the weather is between 80 and 90F. On the other hand, you must apply fertilizer to your cool-season grass when the weather is between 60 and 70F.
  3. Lawn Growth: The ideal time to apply fertilizer is during the active growth of your plants. If there is no active growth, we recommend you wait a few weeks before application.

Fertilizer Numbers for Lawn: What to Look For

An infographic on what to look for when choosing fertilizer numbers

There is much more to fertilizers than just looking for the right lawn fertilizer numbers. Instead, there are also other factors to remember before choosing the ideal fertilizer for your lawn.

These include the following:

1. Slow vs. Fast Release of Nitrogen

Fertilizers can release nitrogen slowly or quickly, depending on the type. Fast release of nitrogen will turn the grass green quickly, and you can also apply them to cold soil.

On the other hand, these fertilizers are also more affordable than the rest. Sometimes, these quick-release fertilizers can also burn your grass or lead to uncontrollable growth.

Slow-release nitrogen fertilizers act slowly, and the grass will grow more cohesively. However, they are not ideal for cold soil and are more expensive.

The fertilizer label will let you know what type of nitrogen the bag contains.

2. Established Lawn or New Lawn

The NPK fertilizer ratio and type of fertilizer will also vary based on the type of lawn you have. If you are trying to create a lawn, then starter fertilizers are the ideal choice.

These will help you establish your lawn in the right way. On the other hand, if you already have an established one, then the information will help you select the right lawn fertilizer numbers.

3. Liquid or Granular Lawn Fertilizer

There are two types of common fertilizers in the market. One comes in liquid form, while the other comes in a drier form.

Most homeowners have the misconception that liquid fertilizer is better. However, we don’t recommend this option.

It is incredibly challenging to ensure the evenness of a liquid fertilizer. If there is no evenness, then you are also at risk of burning some parts of your lawn.

On the other hand, the application of liquid fertilizer also needs to be more frequent than that of dry fertilizer. So, we recommend you keep this in mind when looking for the right fertilizer for your lawn.

4. Homemade Fertilizers

Finally, many people make fertilizers at home, or they use organic fertilizers made in small batches. These have various animal and plant sources.

The good thing about these fertilizers is that the nitrogen releases slowly and will not burn your lawn. So, you don’t need to worry about any damage to your lawn when using such a fertilizer.

How to Begin Early Spring Fertilization in Canada

An infographic on how to begin early spring fertilization in Canada

Now that you know the lawn fertilizer numbers and their meaning, it is time to begin this process for spring. Here are the steps you can follow to begin the spring process:

Step 1: Conduct a Soil Test

First, you must conduct a soil test on your lawn. The soil pH needs to be optimal for a lush lawn to grow.

For example, essential nutrients will be missing if the lawn is new or you have not aerated the grass in a few years. You can purchase an at-home kit to conduct a soil test on your lawn easily.

Step 2: Purchase the Right Fertilizer

After the soil test, you will have a complete picture of what nutrients are missing in your soil. We recommend you invest in a fertilizer that doesn’t have a lot of mulch or other filler.

Good quality fertilizer will have nutrients like nitrogen, calcium, magnesium, and much more. On the other hand, if you want an even better fertilizer, then you can get in touch with our experts at Falcon Landscaping.

Step 3: Ensure that the Temperature Range is Ideal

It is best not to use fertilizer without checking the temperature. For example, if you have warm-season grass on your lawn, then the ideal temperature for adding fertilizer will be between 70 and mid-80s.

On the other hand, if your lawn has cool-season grass, then the ideal temperature range will lie between 60 and 70F.

Step 4: Make Sure the Weather is Dry

Putting fertilizer on wet grass is not a good idea. It is optimal that you add fertilizer on dry grass, and it rains the next day.

However, on the day you plan to fertilize, make sure there is no rain forecast.

Step 5: Utilize a Fertilizer Spreader

As a general rule, it is important to use a fertilizer spreader. Doing this will let you know how much fertilizer you are using on each square foot of your garden.

Be sure to get a spreader that will not pile up the fertilizer in one area. Instead, it should help you spread the fertilizer evenly.

Step 6: Wear Protective Gear

Finally, we recommend you wear protective gear during the process of applying fertilizer to your lawn. While fertilizer is great for your lawn, it can hurt you if you are not wearing protective equipment.

If you are still worried, be sure to contact our landscaping experts in Mississauga to take care of all your fertilizer needs.


What number of fertilizer is best for lawns?

The best lawn fertilizer numbers are ones that offer an optimal balance of the three nutrients. We recommend you conduct a soil test and then determine the number that will serve best.

What is 30 0 10 fertilizer used for?

The 30-0-10 fertilizer number is one of the top-quality fertilizers that will make all parts of your lawn lush. Such a formula is slow release, which will help you conserve water and decrease mowing.

What is the NPK ratio for lawns?

A common NPK ratio for lawns is usually 8-18-12 or 12-16-8. However, you must pick a fertilizer with less nitrogen and more Potassium and phosphorus to start your lawn. With an established lawn, the ratio will be different.

What do the three numbers mean in lawn fertilizer?

The three numbers in the lawn fertilizer stand for nitrogen, phosphorus, and Potassium. These are the percentages of the different nutrients based on the weight of the fertilizer bag.

Final Thoughts

That was everything you needed to know about lawn fertilizer numbers for every season in Canada. Now that you know lawn fertilizer numbers for spring, it is time to get that early fertilization in to keep your lawn lush.

If you still don’t know how to begin this process, you can connect with our lawn care experts to keep your lawn lush and flourishing this spring season.