Fertilize Your Lawn Before Winter? Necessary or Not?

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It seems like we were all gearing up for summer just last week, and now here we are, heading into the chilly months of autumn. While it’s not exactly time to put away the lawn mower just yet, you may be wondering if there’s anything else you need to do before winter sets in. One question that often arises is whether or not to fertilize your lawn before winter.

It’s necessary to fertilize your lawn before winter because it increases its iron level and general health. The grass develops deeper and healthier roots that absorb sufficient nutrients to enable the lawn to survive the winter stress due to frost and ice.

In the rest of this article, I’ll discuss the right time to fertilize your lawn before winter and the type of fertilizer to use. I’ll also discuss what you should never do to your lawn in winter. Let’s get started!

Should You Fertilize Your Grass in the Fall?

You should fertilize your grass in the fall because this season provides the optimum conditions for fertilizer absorption. The morning dew in fall helps the fertilizer to seep into the ground and reach the roots of your grass. Moreover, the cool temperatures in fall breaks down the fertilizer slowly, giving your lawn a steady supply of nutrients throughout winter.

Therefore, there are two essential factors that make fall the best time to fertilize your lawn: morning dew and cool temperatures. I’ll discuss these more in-depth in the following sections.

Morning Dew

Water is essential for the fertilization process.

After applying fertilizer to your lawn, it needs water to wash it off the grass blades and help it seep into the ground.

The fertilizer must be pushed below the tender grass blades to prevent burning. Leaving the fertilizer on the grass blades can do more harm than good to your lawn. Instead of making the lawn lusher, the fertilizer left on the blades will get heated by the sun and burn your grass.

The morning dew provides enough water to wash the fertilizer off the blades and help it seep into the ground without watering the lawn.

It’s worth noting that most plants absorb nutrients through root hairs at the tip of their roots. Therefore, after applying the fertilizer on the soil surface, you need water to wash it into the soil where these root hairs will absorb it for use by your grass.

Cool Temperatures

Fertilizer applied in fall breaks down slowly due to the cool temperatures, providing a steady supply of nutrients to your lawn throughout winter.

In contrast, fertilizer applied in spring or summer breaks down quickly due to the warmer temperatures. This can cause an initial growth spurt in your grass followed by a period of nutrient deficiency because all the nutrients have been used up.

Applying fertilizer in the fall helps prevent this cycle of nutrient deficiency because the fertilizer breaks down slowly, providing a steady supply of nutrients to your grass throughout the winter.

The Ideal Month To Fertilize Your Lawn Before Winter

Timing is crucial when fertilizing your lawn to keep it healthy in winter. Applying a winter fertilizer, also known as a winterizer, to your lawn too late or early can:

  • Weaken the roots of your grass
  • Thin the grass
  • Lead to a patchy lawn
  • Discolor your grass

The best way to determine the right time to winterize your lawn is by knowing your type of grass and its growing season. You need to apply the winterizer when the grass is actively growing so it can be absorbed by the grass and used in winter.

There are two basic types of grass:

  • Cool-season grass
  • Warm-season grass

I’ll go over these two types of grass next.

Cool-Season Grasses

Cool-season grasses are those that thrive in the cool of spring and fall. They can stay green throughout the winter since they need temperatures between 18.33 and 23.89°C (65 and 75°F).

Examples of cool-season grasses are:

  • Hard fescue
  • Bluegrasses
  • Chewings fescue
  • Ryes
  • Tall fescues

The right time to fertilize these grasses is early fall/late summer and late fall. This is the period when these grasses are actively growing. You can rest assured that they’ll absorb the fertilizer before the colder winter season, when most grasses enter the dormancy period.

You should prioritize fertilizing your cool-season grass in September and October since the best time to fertilize these grasses ranges from late summer to late fall.

Fertilizing your cool-season grass too early promotes succulent growth in fall. This is detrimental to your lawn since the grass will be more susceptible to winter injuries.

On the other hand, fertilizing this type of grass too late in the season can cause it to be less tolerant of cold temperatures. This can lead to winterkill.

Warm-Season Grasses

As the name suggests, warm-season grasses thrive in hot and moist climates with temperatures exceeding 90°F (32.22°C). They go dormant in winter when the temperature drops below 40°F (4.44°C) and turn brown since they need to preserve their stored food to remain alive.

Examples of warm-season grasses are:

  • Zoysia
  • Bermudagrass
  • Saint Augustine grass
  • Buffalo grass
  • Centipedegrass

The best time to winterize these grasses is early autumn when they’re still growing. You should stop fertilizing them in September, as this is when most start getting into the dormancy period.

Expert Tip: As with any type of grass (warm or cool season), you should avoid fertilizing when the temperature drops below 40°F (4.44°C). Most grasses are in their dormancy stage when temperatures drop below this threshold. Therefore, fertilizing them will do more harm than good. The same goes for mowing your grass below this temperature.

What Type of Fertilizer Should You Use Before Winter?

Now that you know it’s necessary to fertilize your lawn before winter, which is the best fertilizer for this purpose?

The N-P-K fertilizer ratio, aka the nitrogen, phosphorus, and potassium compositions, is crucial to getting the right winter fertilizer for your lawn.

Nitrogen and potassium are the essential nutrients to focus on when looking for the right winterizer.

When fertilizing your lawn in the fall, you should use a fertilizer with a higher percentage of nitrogen and potassium and a lower percentage of phosphorus.

The following are the ideal N-P-K fertilizer ratios for cool and warm-season grasses:

  • Cool-season grasses: 2-0-1 or 3-0-1
  • Warm-season grasses: 14-14-14

Nitrogen is needed to restore your lawn’s carbohydrate reserves. This ensures the grasses have sufficient food to take them through the winter months up to spring when they start growing.

On the other hand, potassium helps the grasses develop a strong root system. This is essential since the roots help the grass to survive when conditions aren’t ideal for growth. The roots also strengthen the grass to withstand winter stressors like snow, mold, and ice.

A slow-release fertilizer (SRF) is ideal for fertilizing your lawn in the fall. This is because it releases nutrients over an extended period, which means the grass can benefit from the fertilizer even when growth has slowed down due to cooler temperatures.

Organic compost is also an excellent fertilizer for winter since it contains nitrogen and potassium. It also helps improve lawn drainage and aeration.

ID 209894860 | © Maryna Hlushko | Dreamstime.com

Note: You should consider the laws on fertilizer use in your state before applying the winterizer. Some states have banned the use of phosphorus-containing fertilizers to protect their waterways. If you live in such a state, you should use a fertilizer with a zero second number in its ratio, for instance, 3-0-1.

When Is the Right Time To Apply a Winterizer?

When winterizing your lawn, you want the grass to reap as many nutrients as possible from the fertilizer. As such, the time of the day you apply the fertilizer is crucial.

You should apply the fertilizer to your lawn early morning or late evening. This is because the grass can better absorb the nutrients when it’s cooler, and there’s less evaporation.

It would help if you also water your lawn thoroughly a day or two before applying the winterizer. This allows the fertilizer to reach the roots, where it’s most needed.

Applying the fertilizer during the day isn’t recommended, as it will evaporate before getting to the roots.

How To Apply Fertilizer Before Winter

After getting the right winterizer for your lawn, it’s time to get to work. The following are some lawn preparation practices before applying the fertilizer:

  • Clean up the grass: You should mow the grass to keep it even, pick the dead foliage, and rake the leaves.
  • Aerate the lawn: This helps improve drainage and aeration, which is essential for a healthy lawn. You can use a spike or plug aerator.
  • Test the soil: This will help you determine the right amount of fertilizer to use.

Fertilizer Application

You can use a drop or broadcast spreader to apply the fertilizer evenly across the lawn. However, if you have a small lawn, a handheld spreader will work just fine.

Photo 175401938 | © RjGentry | Dreamstime.com

The following are the steps for applying fertilizer:

  1. Set the spreader to the recommended settings.
  2. Start from one corner of your lawn and walk in a back-and-forth motion until you’ve covered the entire area.
  3. Be sure to overlap your passes to ensure even coverage.
  4. Walk around the perimeter of the lawn to ensure you haven’t missed any spots.
  5. Water the lawn thoroughly after applying the fertilizer. This helps the fertilizer to reach the roots.

It’s worth mentioning that you should follow the recommended application rate on the fertilizer bag. Applying too much fertilizer can damage your grass, and too little won’t winterize it effectively.

What Not To Do to Your Lawn During Winter

Winter is challenging for most grass; the ice, frost, and winter mold can significantly damage your lawn. As such, there are many practices you should not do during this time, including mowing and fertilizing.

Don’t Mow Your Lawn During Winter

Mowing your lawn in winter is a sure way to damage and kill most of the grass.

Most grasses stop growing in winter and remain dormant. Dormant grass won’t recover quickly from the cutting stress.

Moreover, dormant grasses have few photosynthetic blades. Thus, mowing removes these blades, further reducing the ability of the grass to make food.

Short grass (below two inches or 5.08 cm) in winter is at a greater risk of dying due to reduced sunlight exposure. Therefore, the best thing to do for your winter lawn is to avoid mowing it.

You can have the last mowing session in the late fall, just before winter.

What’s the Ideal Height To Mow Your Grass Before Winter?

As already discussed, you should mow your grass in the fall, just before winter. However, grass height is a grave matter you must consider.

Too short or too tall grasses aren’t ideal for winter. Besides not absorbing sufficient light for photosynthesis, too short grasses lack adequate crown insulation. On the other hand, long grasses are exposed to snow mold and other fungal diseases.

The ideal height for your grass before winter is 2 to 2.5 inches (5.08 to 6.35 cm). This height is just right for most grasses to protect them from the winter elements.

You should raise or lower the mower blade to achieve this ideal height. It’s advisable to consult the manual or a professional if you’re unsure how to adjust your mower’s blade.

Don’t Fertilize Your Lawn During Winter

Fertilizing your lawn in winter breaks the dormancy, forcing the grass to start growing when it shouldn’t.

This new growth is vulnerable to frost and ice damage, which can kill the grass.

Moreover, the new growth will quickly exhaust the nutrients in the soil, leaving the grass malnourished when spring comes.

The best thing to do is to fertilize your lawn in late fall, just before winter sets in. This way, the grass can store the nutrients and use them when it starts growing in spring.

Don’t Walk or Drive on the Lawn During Winter

Foot traffic and vehicle traffic can damage the grass in winter.

The weight of people and vehicles compacts the snow on the lawn, preventing the grass from getting the air it needs to breathe. The compacted snow also blocks sunlight from reaching the grass, further preventing photosynthesis.

Lastly, this compacted snow creates an environment favorable for mold growth and other diseases.

If you must walk on the lawn in winter, use a path to minimize the damage.


It’s necessary to fertilize your lawn before winter. A properly fertilized lawn before winter is less likely to succumb to diseases, pests, and other problems. A healthy lawn is better able to withstand the challenges of winter and come out looking green and gorgeous in spring.

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