Fall is a good time to fertilize cool season grasses!

fertilize cool season grasses

Right now many of us are wondering how it could possibly be fall already, but it’s a fact. The autumnal equinox has passed, football season is underway, and pumpkin spice flavored foods and beverages are all the rage. If your lawn contains types of cool-season grasses, like Bluegrass, Ryegrass, Fine Fescue or Tall Fescue, the fall season also presents some fantastic opportunities to improve the overall health, vitality and beauty of your lawn. Performing core aeration in the fall loosens the soil, breaks down thatch and allows air, water, and nutrients in. Overseeding immediately after aeration allows more seed to reach the soil as well. But perhaps the most beneficial thing you can do for your cool season lawn is feed it!

Grass is a seasonal plant whose growth rates fluctuate at different times of year. During the fall season, lawns are recovering from the stresses of summer, such as heat and drought. Early fall is a period for vigorous growth in cool season grasses, which take advantage of the milder temperatures and more consistent moisture levels. This new growth and recovery uses up nutrients, which must be replenished. A fall application of a controlled-release nitrogen fertilizer provides the necessary nutrients to keep your turf green and growing longer into the fall season.

Fertilizer For Fall  Applications

Here’s an interesting fact about cool season grasses: as growth above the ground begins to slow, the grass plants are putting more energy into root development, which is essential for winter hardiness and ensures greater turf density the following spring. As you might guess, all of this also requires nutrients. This is why fall fertilization is such an essential part of an effective cool season lawn care program. Depending on where you live, there may be enough time to apply a second, late fall application of fertilizer. We recommend that the applications be 4 to 6 weeks apart. In late fall, when the grass plants are no longer using the nutrients for growth, they begin storing the nutrients in the stems and rhizomes (the root system), which keeps the plants healthier not only over the winter season but also into spring.

What type of fertilizer is best for fall applications? There is no universally correct answer to this question because the nutritional needs of turf grasses vary by region based on predominant grass types, soil composition, and climate as well as when the product is being applied. It should most definitely be a lawn fertilizer, as opposed to a general purpose garden fertilizer. All bagged fertilizer products are required by law to display the guaranteed minimum percentage (by weight) of nitrogen, phosphorus and potassium. Of these, nitrogen is the foundation nutrient essential to any fall feeding program. Nitrogen products can be formulated for quick release, where it becomes immediately available in the soil, or slow release, which becomes available over a longer period of time. Many lawn-specific fertilizers will contain both.

Preparing Cool Season Grasses For Winter

A few cultural practices will also help your cool season lawn prepare for its winter nap. As late fall approaches, begin to gradually bring the cutting height down on your mower. Do this in steps, over the course of several mowing, so that you are never removing too much of the grass blade at once, which would damage the turf instead of helping it. Also never adjust the mower so low that you are scalping the lawn all the way down to the soil surface. If you have a blanket of fallen leaves or other debris on the lawn, rake them up. Leaves can also be ground to a fine mulch with repeated mowing, though it is important to ensure that the resulting pieces have been finely ground. Both of these practices—gradually lowering the grass height and keeping the lawn’s surface breathable by controlling leaf cover and removing debris—will help prevent diseases like snow mold from taking hold.

Have we given you enough to think about? No worries! The easiest way to ensure that your lawn is receiving the correct balance of nutrients, in the proper amounts and at the right time, is to call on your neighborhood lawn care professional at Spring-Green and let us take all the guesswork out of it. We will be happy to answer any questions you have, too.

Is it Too Late to Apply Nitrogen Fertilizer to Warm Season Grasses?


nitrogen fertilizer

The simple answer if you are reading this in late August or early September is “No.”  This decision is based on several different factors.  A general rule is to apply the last nitrogen fertilizer to a lawn that contains warm-season turfgrasses two months before the first frost. Unless you live in the deep south, the last application of a fertilizer that contains a high amount of nitrogen would be September 15 at the latest. If you live in the more northern areas, you run the risk of turf damage and lawn disease development if nitrogen is applied after September 1st.  Of course, these are based on averages, so there is a little “wiggle” room, but not much.


Applying Nitrogen Fertilizer to Warm Season Grasses

Centipede, St. Augustine, Hybrid Bermuda and Zoysia grass are the most common warm season grasses and they usually go dormant in the late fall.  Applying a high rate of nitrogen after the middle of September for the more moderate warm-season areas will increase the shoot and leaf growth while the plant is slowing its growth.

It is important that these grasses have a chance of “harden-off” before going dormant.  If pushed to grow, the tender new growth is more susceptible to freeze damage.  These succulent shoots are prone to being attacked by a common cool-season disease called Large Patch.

Another problem with fertilizing later in the fall is that it may increase the number of cool-season weeds that germinate. Weeds like henbit, common chickweed and Shepherd’s Purse are considered winter annuals and will grow and spread while the desired grasses have slowed down growing.

Determining Nitrogen, Phosphorus and Potassium in Fertilizer

The three numbers on a bag of fertilizer indicate the percentage by weight of nitrogen, phosphorus and potassium in the bag. The number one nutrient needed by turf is nitrogen. Here is a chart that provides the amount of nitrogen each turf type needs for the entire growing season.

Warm Season Grass#’s of Nitrogen Per Year
Hybrid Bermuda5 to 6 lbs.
Common Bermuda4 to 5 lbs.
Centipede Bermuda1 to 2 lbs.
St. Augustine grass (sun)3 to 4 lbs.
St. Augustine grass (shade)1 to 2 lbs.
Zoysia grass3 to 4 lbs.


If you haven’t applied the recommended amount of nitrogen to your lawn this year, don’t try to catch up now.  In regards to the other two nutrients, phosphorus and potassium, they are required, but they are usually found in an abundant amount in the soil. The only way to tell if the lawn needs either of these two nutrients is to have your soil tested.  Most cooperative extension services offer this service at a low fee of less than $25.00 per sample.

If you live within the area that has a first frost date of mid-October, try to fertilize between Labor Day and the end of September, depending whether you are in the northern or southern parts of that zone. If you are not sure, contact your neighborhood lawn care professional at Spring-Green.