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The Ultimate Guide to Winter Fertilizer

Applying a winter fertilizer is an important lawn care measure that ensures your grass survives freezing temperatures and is ready to flourish in the early spring. Read on to learn about winter fertilizers, their benefits, and tips for application.

Author Icon By Stephanie Koncewicz Updated 01/07/2024

When fall and peak growing season come to an end, it’s important to consider a final fertilizer application to prepare your lawn for the harsh winter months. This preventative measure can help your lawn survive the damaging effects of the cold and give it a leg up when spring arrives.

In this guide, we break down the benefits of winter fertilizers and tips on how to select the right one for your grass.

What Is Winter Fertilizer?

A winter fertilizer, also known as a winterizer, is a lawn care treatment applied to grass in the late fall to encourage food storage in the winter and proper root system growth in the springtime. This type of fertilizer is distinct from fall lawn treatments, which immediately encourage root growth and are applied before a winter fertilizer.

Winter fertilizers should be applied after your healthy lawn stops growing, when it’s green on top and active below the surface. These fertilizers are considered an important last step in your annual lawn care maintenance, ensuring that your grass stays healthy when dormant.

How To Use Winter Fertilizer

Most winter fertilizers are applied after the last mow of the fall season, when your lawn is done growing and preparing for dormancy. At this time, your lawn can take in the fertilizer’s provided nitrogen and store it for later use.

Prime application is usually around November, though people living in some northern states may need to apply the fertilizer a bit earlier due to the weather getting colder earlier. Waiting too long may cause your grass to succumb to mold and ice issues in the winter, while applying too early may prevent your lawn from reaching its full potential.

How To Choose the Best Winter Fertilizer

A quality winter fertilizer incorporates two main ingredients: nitrogen (N) and potassium (K). Nitrogen helps restore your lawn’s carbohydrates, ensuring it has enough food to last through the colder winter and spring months. Potassium also provides your grass with nutrients, although these help the grass prevail through cold-weather stressors like stress and mold.

Most winterizers have a 2:1 ratio of nitrogen to potassium. This proportion of essential nutrients helps give your lawn the proper combination of food storage and energy to prevail in the winter. It’s also important that your fertilizer consists of a water-soluble, quick-release formula instead of a water-insoluble, slow-release formula for quick release of nitrogen nutrients. You can check the ingredients of a winterizer by reading the information listed on its bag.

Important Tips for Using Winter Fertilizer

While applying a winter fertilizer is similar to many other lawn treatments, there are a few things to consider. Here are some important tips for using winter fertilizer:
Conduct a soil test before application—Before purchasing and applying a winterizer, conduct a soil test to determine its potassium levels. If your soil displays adequate levels, you may not need to give it more potassium. While soil tests can be done on your own, you may want to consider hiring a lawn care service, such as TruGreen, to ensure the tests are conducted properly.
Inspect the fetilizer’s ratio—While nitrogen and potassium are essential for winterizers, many also include phosphorus (P). Some of the best winter lawn fertilizers incorporate a formula with an NPK ratio of 16-4-8.
Don’t apply winterizer too late—Generally, winter fertilizer should be applied in November or earlier, depending on your climate. Try to avoid applying in early December, as the nutrients within the formula may not take hold in time to protect the grass from the harsh conditions.
Use less fertilizer than the recommended amount—Use around ⅓ to ½ of the amount of fertilizer recommended on the package. This saves you money on application and prevents over fertilizing.

Frequently Asked Questions

Is winter fertilizer necessary?

A winter fertilizer is one of the most important lawn treatments for your yard, as it protects the grass during the winter and prevents unnecessary damage to your lawn. However, if you feed your lawn with fertilizer and compost during the warmer months or have a lawn with an adequate amount of potassium, you may not need this additional treatment.

When should I apply winter fertilizer?

Apply a winter fertilizer to your lawn when it’s finished growing but not yet dormant underneath the surface. For many parts of the country, this is around November, though it may be time to apply sooner if you live in colder climates.

What is the difference between fall fertilizer and winter fertilizer?

The composition of a fall fertilizer is a bit different than its winter counterpart. While both fertilizers contain potassium, winterizers usually contain a higher amount of this mineral to sustain your grass when the ground freezes.

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