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When To Apply Winterizer Fertilizer?

Winter is one of the toughest times for our lawns, and ensuring that they get through this season without any difficulties is important. Luckily, we’ve got a fertilizer designed specifically with your needs in mind- a winterizer!

A winterizer fertilizer is a late fall fertilizer designed to help lawns store more food for the cold months and encourage thick growth in spring.

But the question here arises “when to apply winterizer fertilizer”. Knowing when to apply it will ensure success in the current year as well as future ones too. This guide answers in detail, so read on to give your crops the best feel throughout winters.

The Best Time to Apply Winterizer Fertilizer

Applying a winterizer fertilizer in late fall can help prepare your lawn for the long, cold winter. It will also minimize damage to grass from freezing temperatures.

Furthermore, it creates healthier-looking blades after getting hit with needles more frequently than normal as we head into the winter months.

If you want the best chance at success with a winterizer, you must apply it at the right time. Here are the points you should consider to guess the perfect time of applying winterizer/fall fertilizer.

  • For winterizer, you should observe the shoot growth of your turf and notifies before it has stopped.
  • Apply your winterizer after you’ve finished the last cut for the season. It can be shorter than a normal height, so it’s best to do it then.
  • To get the best results, you should apply a winterizer before snow falls or frostbite. Do it before snowfall season so that grass doesn’t have too long of an active root system during winter when there are no leaves on it.
  • The ideal time for this would be in late November or early December, ensuring that your lawn is still green (start of the fall season) when applying.
Scotts Turf Builder WinterGuard Fall Lawn Food When To Apply Winterizer Fertilizer
Scotts Turf Builder WinterGuard Fall Lawn via

Things To Consider For an Effective Winterizer Application

The old belief that winterizes should be low in nitrogen and high on potassium has been disproven by recent research. Instead, an ideal winterizer will have most of its fertilizer as quick-releasing WSN (water-soluble nitrogen) rather than slow-release WIN (water-insoluble nitrogen).

A label with this information would show: “This brand contains 90% water-soluble N.” Some important things you should consider for an effective winterizer application are:

1. Apply When Grass Stops Growing

You should apply a winterizer when the grass stops growing in fall, but the roots are still active. It will make sure that all parts of your lawn are covered in an even coat.

It helps them freeze evenly and safely during those cold fall days without harming anything or breaking down too quickly due to its low temperatures (below freezing).

2. Apply Less

It would help if you didn’t leach winterizer into groundwater to do more harm than good. For example, if there are 5lbs per 1000 square feet on your bag, only apply up to 2/3 of this total amount for late fall use because less will be absorbed in cold weather.

Usually around .25-.5# N per 1k of coverage is sufficient, which should get one through two weeks’ worth before snow starts bonding with soil again. With liquid fertilizers, you can go even lighter.

3. Use a Good Quality Winterizer

You should use a good quality fall fertilizer with optimum nitrogen, phosphorus, and potassium number ratios.

You can use Scotts Turf Builder WinterGuard Fall Lawn Food, 12.5 Lb suitable to all kinds of grass types and covers almost 5 000 Square Feet. It is crucial to know the N-P-K ratio of your winterizer before you spread it on the plants.

Scotts Turf Builder WinterGuard Fall Lawn Food When To Apply Winterizer Fertilizer 2

4. Source Of Nitrogen

The most common fertilizers used for winterizing your lawn are water-soluble nitrates and ammonium sulfates. Check the label to see if it contains phosphorus or potassium as well since they give quick-release nitrogen. They can be present in small amounts in organic fertilizers.

Fish wastes make a great alternative when you don’t mind its pungent odor–they’re approximately 80% liquid at room temperature (plus they have other benefits too).

5. Use Only On Cool-Season Grasses

The winterizer fertilizer is a great option for cool-season grasses like bluegrass and fescue. It is not meant for warm-season grasses such as St. Augustine and bermudagrass.

It helps lawns maintain their green color during the chilly months and reduces browning when temperatures dip below freezing point in wintertime.

When Not to Apply a Winterizer Fertilizer

You should not apply winterizer in the following situations:

  • During the fall season with the hoping that it may accelerate grass growth, but it does not.
  • During cold months as the plants are already suffering from discoloration caused by harsh weather.
  • On the sandy soil because it causes nitrogen leaching, which could result in groundwater contamination.
  • For warm-season grasses, i.e., centipede grass, St. Augustine grass, Zoysia grass, Bermuda grass, etc. These grass types are best suited to thrive in summer and are dormant in late fall, so using winterizer can be a wastage of money.

Follow These Tips When Using Winterizer Fertilizer

  • Apply in mid to late November
  • Avoid applying in late December
  • The package shows a proper NPK ratio, and the nitrogen should be water-soluble.
  • Use ⅓ to ½ of the amount of fertilizer that is recommended on the package (as the prescribed amount often scorch the grass)
  • Test your soil earlier, and if it contains the right amount of K, you won’t need the booster
  • The winterizer package must be labeled with the correct NPK ratios


One of the most widely-known ways to keep your lawn green and healthy all winter is using a winterizer. The best way to enjoy winterizer’s benefits is by applying it at the right time, and for that, you must:

  • Apply it in early fall when the shoot growth of turf stops and before ground freezes.
  • Use on cool-season grasses only.

We hope that this guide helped you learn more about using a winterizer. If there are any questions, feel free to leave them below, and we will get back to you as soon as possible!