Fall Fertilizing 101

While it’s easy to associate spring, the season of new life, with lawn regeneration, don’t let the cooler pockets of fall fool you!  Autumn is actually the best time of year to fertilize grass. After surviving the brutal, dry heat and heavy foot traffic of summer, grass regains its strength before winter with a healthy fertilizing treatment. Fertilizers contain critical nutrients that are essential for growth (just like taking vitamins!): nitrogen, phosphorous and potassium. This trifecta helps develop a deep and thick root system that will allow grass to persevere through next summer. We’re taking you back to high school science class to dissect the best approach to DIY landscaping. After all, lawn care does involve a bit of science, and there is no one-size-fits-all technique or acceptable amount of guesswork to figure out what your grass needs.

Conducting a Soil Test

The absolute fool-proof method to determining what nutrients your lawn is lacking is to take a soil test. Test for the three chemicals/minerals mentioned above (nitrogen, phosphorus, potassium), as well as pH level. See how you can easily test your own soil here. taking-soil-testing-machines-to-farmers The pH level will indicate your soils chemistry. If it shows a need to reduce acidity, apply lime; If alkalinity needs to be reduced, apply sulfur. Also assess if your yard is planted with cool or warm season grasses. It’s the cool season breeds (Kentucky bluegrass, bent grass, and rye-grass varieties) that benefit the most from fall fertilizing, as they are generally found in regions that experience cold winters and hot summers.

Types of Fertilizer

The two basic kinds of fertilizer are natural, and manufactured. Natural may contain a variety of substances including manure and decomposed plant matter, while manufactured is created from synthetic materials and minerals. Check the N-P-K concentration on a bag of fertilizer by weight. For example a 50 pound bag with a label reading 5-10-5 contains 2.5 pounds ( 5%) of nitrogen, 5 pounds (10%) of phosphorous, and 2.5 pounds (5%) of potassium. Larger numbers specify greater concentration of the nutrients. The concentration determines the surface area that a bag of fertilizer will cover, so follow the manufacturer's application guidelines.


You can apply either blend one of two ways: by broadcasting dry blends or spaying liquid forms. Dry types are most commonly water soluble, and seep into the soil over a longer period of time. Liquid fertilizers have almost immediate impact. But the results are shorter lived. Most lawns require an average of 4-6 applications of fertilizer annually, depending on fertilizer blend, grass type and soil concentration. Cool season grasses generally need a minimum of 4 applications, while warm season grasses typically demand monthly applications to sustain growth. While blade growth slows or stops altogether during cooler months, the root system continues to grow. Performing two applications during fall properly prepare your yard for winter. Apply the first treatment in late August or early September, the second in late October to mid-November. Any fertilizer penetrates soil more easily when the ground is moist. If your lawn is a particularly dry, give it a good watering, then wait a day to fertilize to ensure maximum effectiveness. In order to ensure optimal fertilizer penetration, you should first consider dethatching your lawn.  An easy-to-use electric dethatcher like the Sun Joe AJ800E is an often overlooked, but essential tool for lush green lawns. Dethatchers help to remove thick dense layers of thatch on your lawn to allow for water, oxygen, nutrients and fertilizer to penetrate the deeper soil layers. For cool-season grass, the best time to dethatch is late summer or early fall, when your grass is growing most rapidly.  For warm-season grass, dethatch in late spring or after the second mowing. Before dethatching, mow a little shorter than usual with an easy-to-use electric mower like the Sun Joe MJ403E that features a 7 position height adjustment lever, so you can tailor the cut to your needs.  
Most Popular
Recommended Articles