Like spring, fall is a crucial time to boost your lawn's nutrients — only this time, your turf is preparing to go dormant. If your grass is a cool season type, fall is a great time to fertilize your lawn to stimulate strong root growth. Warm-season grasses will naturally start going dormant as temperatures drop. Cool-season grasses will grow throughout the winter, so ensure you’re familiar with your grass type and area.
Lawn care in the fall marks the beginning of preparing your turf for winterization. A drop in temperature can “shock” weak grass, opening the way for pest, weed, and lawn disease problems in the future. Use fall to promote strong, healthy grass that will return to its former glory in the spring.
What Does It Mean When My Grass Goes Dormant?
If you’ve never heard of the idea of your turfgrass “going dormant”, here’s a brief explanation. Chlorophyll is the chemical that gives grass its vibrant green color and helps plants create food using photosynthesis. When temperatures change, these environmental stresses provoke a response in your turf. Grass responds by prioritizing root health over leaf growth, going into a state of hibernation and turning brown. This is known as dormancy.
You’ll need to start your fall lawn care before your grass goes dormant. The best time to do this is September/October, depending on when the first frost is in your area. Generally, when temperatures fall below 41° Fahrenheit — your lawn will begin going dormant. This is the best time to decrease your mowing frequency, as turfgrass won’t grow much more in winter.
Related: Your Ultimate Winter Lawn-Care Guide
1. Rake up Leaves and Keep It Clean
Keeping your lawn clean is a job you should be doing year-round. Leaves pile up on your lawn during the fall, which can suffocate your grass and inhibit grass growth in the spring. Dead leaves also trap moisture, which provides an ideal environment for pests (like grubs) to hide and lawn diseases to develop in moist conditions.
You have two options when removing dead leaves from your lawn. Firstly, you can use a leaf rake or leaf blower to remove leaves for compost or responsible disposal. Use your mower to pick up leaves by fixing the bag attachment to collect leaves and debris.
Another option is to use your mower to chop leaves into small pieces to create mulch that will fall into the lawn canopy. Organic matter like dead leaves can benefit your lawn, adding a small amount of the macronutrient nitrogen, which helps keep your turfgrass green. An added benefit of using mulch derived from tree leaves is that it can reduce the risk of weed seeds germinating in your soil.
At the start of fall, determine the mowing height you want to maintain when the lawn is dormant. Shorter grass will be resilient to diseases like snow mold in the spring, while grass that is too long can encourage lawn diseases. For warm-season grasses, aim for a height of 2.5" or shorter.
To prevent lawn diseases from exploiting your lawn in damp conditions, you can apply a fall fungicide like Headway G.
Common lawn fungi such as brown patch, dollar spot, and fairy ring stand no chance against Syngenta’s Headway G. It combines two broad-spectrum fungicides to kill many lawn diseases. Covering up to 15,000 sq. ft, it's safe for all grass types and can be applied easily with a broadcast spreader.
Fall Liquid Fungicide
If you’re looking for a fast-acting liquid fungicide to deliver exceptional disease control, Pillar SC Liquid Fungicide is an excellent choice. It controls up to 26 cool and warm-season common turfgrass diseases like brown patch and dollar spot and is safe for all grass types. For best results, use a backpack sprayer, this spray tip, and the appropriate protective clothing, eyewear, and gloves.
Final PGR Application
Around September is when you’ll make your final application of a plant growth regulator if you’ve been applying it every month. Plant growth regulators prevent your grass from growing too quickly with shallow, weak roots. Plant growth regulation will provide healthy and resilient grass — saving you money and time on pest, weed, and disease control costs.
Primo Maxx is one of the best plant growth regulators in lawn care. Primo Maxx comes in a convenient 4 oz container, which, once diluted with water, is enough to treat 7,000-16,000 sq. ft. The built-in measuring cup ensures easy application too.
Once your lawn is clear of debris, a soil test can help determine your lawn's specific pH and nutrient levels. Most grass prefers soil with a neutral pH, so if it's too alkaline or acidic, you can use a pH adjustment product to raise or lower pH levels in your soil.
Use your soil test results to determine which lawn fertilizer to choose. You’ll see the three main macronutrients your lawn needs (nitrogen, phosphorus, and potassium) abbreviated to their corresponding chemical symbol: “NPK” on most fertilizers. Cross-check the results of your soil test when you’re selecting your fertilizers. Lawns lacking in potassium, for example, would benefit from a fertilizer high in potassium.
2. Core Aeration, Overseeding & Top Dressing
Over the winter, your lawn can become compacted, leading to poor drainage and flooding. To help mitigate this problem, core aerate your lawn before going into winter. Core aeration will improve the circulation of nutrients, getting the most out of your lawn fertilizer application.
Core aeration works by punching 2 - 4” holes in turf to remove soil plugs with a specialist tool or using a rake or hoe (for spike aeration). Eventually, these soil plugs break down and return quality nutrients to the soil.
After core aeration, take this opportunity to top-dress your lawn with a thin layer of compost and sand mixed (top-dressing). Rake over the plug holes to improve the porosity and quality of your soil. If you have bare patches in your lawn, you can overseed in the fall, spreading the grass seed into depleted patches.
TOP TIP: Mix your grass seed with play sand to prevent it from blowing away, and invest in a lawn leveling rake. This is particularly useful for spreading organic material for top dressing and overseeding.
3. Fall Lawn Fertilization
Cool-season and warm-season grasses can benefit from a lawn fertilizer application in the fall. When your grass goes dormant, it stores valuable carbohydrate reserves during the winter to be more resilient to disease and damage. When spring comes around, your turf will draw on these reserves for energy. Fertilizing your lawn in the fall will make lawn maintenance easier in spring, so you can begin the year with healthy grass.
The prime time to fertilize your lawn in the fall is after core aeration when the soil is more porous. The best lawn fertilizers to use in the fall are potassium based. This is because potassium helps turf manage environmental stress well and can protect grass roots from frost.
The Best Fall Lawn Fertilizers
For beginner lawn care enthusiasts, we recommend using granular fertilizers for easier application. You can also use these lawn fertilizers when the temperature warms up in summer.
Stress 12-0-24 is high in potassium aiding in water retention and uptake. It contains 12% slow-release nitrogen, humic acid, and sea kelp, which will feed your turf well, encouraging a quicker green-up in spring.
Sulfate of Potash
Sulfate of Potash helps with stress recovery and disease resistance — an ideal choice for the fall. Each fertilizer granule is polymer coated, minimizing waste and providing slow-release nutrients with long-lasting effects.
If you prefer using a liquid lawn fertilizer, try Mirimichi Green's Release 901C™. It’s environmentally friendly and extends nutrient availability in the soil for 120 days — three times as long as most fertilizers.
For application tips and tricks for liquid and granular lawn fertilizers, read this section of our comprehensive article on lawn fertilization.
4. Fall Pre-Emergent Application
Weed killers can either be pre-emergents or post-emergents. Pre-emergent weed killers target weed seedlings and prevent them from becoming established. Post-emergent weed killers target the weed after it’s visibly growing on your lawn.
Pre-emergent herbicides can prevent a weed invasion during the fall and winter when grass is especially vulnerable. As with lawn fertilizers, pre-emergents come in liquid and granular forms. Granular pre-emergents are, again, easier to apply but are more slow acting. Liquid pre-emergents are fast acting and equally potent but require greater amounts of precision to apply correctly.
TOP TIP: For all liquid lawn product applications, we recommend using a turf mark dye indicator to easily see where you’ve already applied the product.
Dithiopyr pre-emergent is safe for cool and warm season grasses. It’s a herbicide that will kill weeds without killing your grass but will also feed your lawn (as it contains nitrogen). Dithiopyr will prevent weeds like Clover and Poa Annua from establishing themselves in the fall. A single application will give you around four months of protection against various weeds.
5. Final Fall Lawn Care Tips
Technically, your winter lawn care starts in the fall, preparing your grass for winterization. But be wary about watering your lawn in the fall. If your area receives at least 1” of weekly rainfall, you won’t need to add water on top of this. Remember to stop mowing your lawn and watering it (if you need to) when the ground freezes over. Practicing these fall lawn care tips will make turf maintenance far easier next year, so make sure you’re organized this September.
Read our spring lawn care guide to ensure your lawn care schedule is ready for next year.