Winterizer Fertilizer - Is It Just a Marketing Ploy?

This time of year, the first thing you see when you walk into Home Depot or Lowe's are several different bags of "winterizer" fertilizers. Advertisements make big promises about winterizer fertilizers, but do they really deliver? This article covers the most important details pertaining to fall fertilizing and whether or not you should buy one of these winterizer fertilizers.
Winterizer Background
The Scotts® company single-handedly developed a niche in the fertilizer business known as "winterizer". According to Webster's Dictionary, the word "winterize" means to prepare for winter. Scotts® has really branded "winterizer" fertilizers and even had the name trademarked. Initially, Scotts® was denied by the Trademark Examining Attorney, but an appeal reversed the decision. Scotts® now uses the name Scotts® Turf Builder® WinterGuardT Fall Lawn Fertilizer for their product. As far as I know, this is the same as their original winterizer. The company carries more than 60% of the U.S. fall/winter fertilizer market, which makes Scotts® the most popular brand in the U.S.
What's the Difference?
scotts winterizer fertilizer bag
Scotts® WinterizerT
Fertilizer bags always have three numbers printed on the front which represent the percentage of the major active ingredients in the bag. They are always listed in this order: nitrogen (N), phosphorus (P), and potassium (K). A common lawn fertilizer formula is 29-3-4, which means the bag contains 29% nitrogen, 3% phosphorus, and 4% potassium. Winterizer fertilizers are essentially regular fertilizers with more potassium and slightly less nitrogen. Scotts® WinterGuardT has a formula of 22-3-14.
What Does It Do?
Potassium plays a big part in winterizing because it has been shown to improve cold tolerance and enhance the root systems of turfgrasses. Because lawns use nitrogen more than any other nutrient, winterizers still provide plenty of nitrogen for late fall even though "winterizer" is usually associated with potassium. Some experts believe that the winterizer application is the most important fertilizer application of the year. The extra benefit occurs because the roots absorb and store the nutrients as they grow until the ground freezes. Those nutrients are then available when temperatures warm in the spring for a quick green-up. Grass plants store up energy (or carbohydrates) in the fall for two main reasons. Blade growth slows down and less transpiration (or evaporation) occurs due to cooler air temperatures, but photosynthesis is still occurring. Scotts lawn care recommends a winterizer application can encourage grass plants to store more energy in the fall because temperatures are lower and blade growth is minimal. So, the intent of a winterizer application should be to provide nutrients for optimal energy storage during the fall season.
When Should I Apply Winterizer?
Winterizer should be applied sometime during October or November. Because every lawn is different and temperature varies between climates, here are some things to look out for before you fertilize. If your lawn has already shown significant discoloration due to low temperatures, you should skip a winterizer application this year. Also, if you have sandy soil, you may want to avoid fertilizing during the fall because sandy soil is prone to leaching nitrogen which can contaminate ground water. If you have over-seeded a warm season grass with a cool season grass, you should not apply a fall fertilizer.
Is Winterizing Necessary?
Winterizing has the benefits of strengthening roots for winter, lengthening the time your grass stays green in winter and inducing an earlier green-up in spring. Winterizing is sometimes a controversial issue and some experts discourage it, but I believe it can and will benefit your lawn.