Fall Lawn Fertilizer FAQ

Fall is here and in many parts of the country, that means thinking about getting your lawn ready for winter weather like frost and snow. For others, it means preparing for a seasonal shift by aerating, mowing your grass shorter than normal, and fertilizing.

Fall is the perfect time to fertilize because it helps strengthen the grass’ roots so they can survive the winter and grow beautifully in spring. While the process of fertilizing can seem quite simple, there are a few helpful tips that can ensure your success.

We’re answering all the most common and most frequent questions about fertilizing your lawn in fall with our fall lawn information guide.

Why should you fertilize in the fall?

As plants grow and mature, they deplete the soil of essential nutrients. It’s important to replenish the soil regularly to be sure your lawn has everything it needs to thrive. Fertilizer should be applied at regular intervals and contain a good mix of nitrogen, phosphorus, and potassium.

The cooler fall temperatures mean less stress on your grass than in the heat of summer. Some grass may actually grow dormant during late summer as a result of too much sun and not enough water. The fall gives grass a chance to recover and gives your lawn a strong base for the active growing season in the spring.

What months during fall should you fertilize?

Although it’s important to aerate and reseed in early fall, fertilizing can be done during September or October and even later. This is because even after green grass yellows and browns, the roots are still working to absorb as much nutrients as possible before winter sets in. The grasses roots will still respond to fertilizer during these later fall days.

Even after the first frost, you can (and should) still apply fertilizer to your lawn. Feeding your lawn in late fall is similar to what animals do before hibernation —they fill up to sustain themselves through winter. Until the soil (where the roots grow and strengthen) freezes, your grass will benefit from fertilizing.

What do the numbers mean on the bag?

Fertilizers are made from a variety of ingredients. The three most effective, and therefore most common, are nitrogen, phosphorus, and potassium. The ratio of these three nutrients is represented by the three numbers on the bag. If you see 10-10-10, it means the bag contains an even mix (10% each) of nitrogen, phosphorus, and potassium. The remainder is carrier product.

What is the best kind of fertilizer to use in fall?

The best type of fertilizer for most grasses in the fall will be one that is high in nitrogen. In the early fall days of September, use a 20-8-8 formula (or similar nitrogen rich) fertilizer. The nitrogen will encourage strong blade growth, especially after a hot summer. The nitrogen will help your grass continue to grow green and full through October and November (in some parts of the country).

Later grass fertilizer applications (October and November) should be with a formula that has a bit more phosphorus. A mix like 13-25-12 will help strengthen the root system to prepare it for the long winter. It is critical to treat these roots now so that by spring, your grass will be ready to grow lush and green.

How much fertilizer should I apply?

Getting the proper dosage of fertilizer is important. Applying too much fertilizer can be just as bad as not applying any fertilizer. In general lawns do best with 1 pound of soluble nitrogen for every 1000 square feet or 1 1/2 to 2 pounds of slow-release nitrogen for every 1,000 square feet.

How often should I apply grass fertilizer in fall?

How often you apply fall fertilizer depends on where you live. If you live in the north, you should look to fertilize twice. Once in early September and then again 6-8 weeks later.

If you live in the south or have warm season grass like Bermudagrass, St. Augustine’s grass, zoysia grass, or carpet grass, one application around Labor Day should be enough.

What is the difference between slow-release and quick-release fertilizer?

Slow release and quick release fertilizers generally refers to the release of nitrogen — the primary nutrient responsible for growth.

Slow-release fertilizers are designed to slowly leach out the nitrogen in the fertilizer over the course of time. This controlled release can help regulate how much, and how often your grass is “fed.” This means slower but steadier growth and less frequent applications.

Quick release fertilizer, on the other hand, releases a dose of nitrogen and nutrients almost immediately. This will result in noticeable results sooner but can also run through the soil more quickly requiring more frequent application. Quick release formulas are also at greater risk of fertilizer burn.

What is the best way to apply grass fertilizer?

There are several different types of spreaders that can be used to fertilize. They are each designed for specific purposes so consider the size of your lawn first.

For large lawns or when you want to spread fertilizer across a wide area, use a broadcast or rotary spreader. Fill the hopper on a tarp to easily clean stray fertilizer. Close the hopper and begin by covering the perimeter of your property. Then fill in the middle in an orderly and systematic manner to ensure even coverage.

For smaller areas or for more concentrated coverage, choose a drop spreader. You can overlap on each section or pass to get even adequate coverage but be sure to close the hopper at the end of each section. A handheld broadcast spreader can also be used for small lawns or if you only want to cover certain portions.

Should I use organic grass fertilizer?

In terms of fertilizer, organic refers to any mix that is minimally processed. Nutrients are not extracted and refined but rather remain in their natural form. The other alternative is a chemical fertilizer which means its nutrients are not in the “natural” form.  Organic fertilizers are made from plant and animal waste and powdered minerals.

There are advantages and disadvantages of both organic and chemical fertilizers. Mainly, organic fertilizers are renewable and sustainable which is better for the environment. However, they are reliant in nature to break down in the soil and may not yield fast results. Chemical fertilizers are more reliable, predictable, and will work more quickly.

Do I need to mow, aerate, or rake before applying fertilizer?

While not required, mowing, aerating, and raking before you fertilize in early fall will improve your results. Mowing and taking remove excess debris making it easier for fertilizer to reach the soil where it can then get to work. Similarly, aerating helps fertilizer reach the grasses root system to strengthen and prepare it for winter.

Does fertilizer expire?

Fertilizer does not expire and can be used from one season to the next. However, there’s no need to have a bunch of it around taking up space unnecessarily. Buy just as much fertilizer as you need. Then be sure to properly store it in a cool, dry place so it does not clump together making it more difficult to spread evenly.

Fertilizing in the fall doesn’t have to be a mystery. Follow these guidelines and your lawn will be the envy of the neighborhood.

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