Fall is the time to get your turf caught up from the stress of summer and ready to thrive through the winter. Whether you’re growing warm or cool season grass in your lawn you can give your turf a boost, kill unwanted weeds and be ready to put the lawn “to bed” for the winter.  Fall fertilization means that come spring you’ll be miles ahead of the game with a happy, healthy, ready-to-play lawn.
Fall fertilization basics: Why this is the best time of year to feed the lawn.
Warm season and cool season grasses can benefit greatly from fall fertilization.  Cool season grasses grow best when daytime temperatures are between 60 and 75°F. In the spring and early fall this equates to more mowing because the leaves and other above ground parts are rapidly growing.  Though in fall this also improves turf density as new shoots and stems develop as well.
As fall begins to move into winter, however, the roots and below-ground structures are the primary growers.  Fall fertilization feeds root growth without causing extra mowing.  Cool season grasses can expand the reach of their roots and store carbohydrates (food the plant makes for itself) in them for spring and summer health when they can’t easily photosynthesize (make it’s own food).
Warm season turf has a different growing pattern than cool season but in the fall it too is sending carbohydrates to its roots, rhizomes and stolons to prepare for winter survival.  Fertilization in warm season grasses ends sooner than in cool season – after the first frost warm season grasses are mostly done growing until spring.
Have you done your Think-Soil™ soilANALYSIS?
If you’ve already completed your soil analysis be sure to consult your results for your individualized nutrient plan.
If you’re new to growSMARTLawnandGarden.com we recommend completing a Think-Soil™ analysis of your yard before applying fertilizers.  Each analysis provides essential information on your lawn’s relative levels of organic matter, pH, lime requirement, and amounts of both macro and micro plant-available nutrients.  This way you can be sure you’re feeding your grass only what it needs and not needlessly throwing away money on products that won’t contribute to your plants’ health.
We’ve designed Think-Soil™ soilANALYSIS to be easily understood at a glance based on the conditions found in your lawn or garden!   Simply go to think-soil.com, and click on Purchase a Soil Test in the top menu. Follow the instructions or watch the YouTube video demonstrating how to take a soil sample from your garden or lawn.  Simply place your sample in the pre-paid envelope and give to your postal carrier.
Your results will be available on think-soil.com within 36 hours after receipt at our WayPoint Lab.  We’ll notify you by email as soon as your results are posted.
Now you’ll have a scientific analysis and a list of products and procedures designed around precisely what your soil needs to optimize fertility depending on what you are attempting to grow.
Fertilization: Which products and when to use them.
For most soils and lawns the same fertilizers can be used because in this case we’re looking to feed the grass precisely what it needs rather than build the soil.  A good mixture of readily-available and slowly-available nitrogen applied at the right rate and timing will give your lawn just what it needs in nitrogen to build and fill its roots with potassium to help it “winterize.”
In the past universities have also recommended phosphorus be applied with the fall fertilization but new research indicates that most soils have a more than adequate phosphorus supply for turfgrasses.  To prevent dangerous pollution problems many municipalities and states now restrict phosphorus applications to seed application or when soil tests indicate the need.
Warm season grasses do best with 1lb. of N (nitrogen) is applied per 1000ft2 in warmer September weather, with an additional ¼-½lb. of N/1000ft2 every 4-6 weeks until the first frost.  Dormancy begins with the first frost for warm season grasses so fertilization beyond this point is not needed until it begins to green up again in the spring.
Cool season grasses can be fertilized with ½-1lb. of N/ every 4-6 weeks while the grass remains a strong green color and while the ground is unfrozen.  The final application of fertilizer occurs, ideally, just after the last mow of the season.  It’s hard to pinpoint this time precisely, of course, but as you pay attention each year you can start to get the feel for when this occurs in your climate.  This fertilization is directly utilized by the roots and provides the greatest benefits for overall strength and spring green-up.
Homeowners who prefer to do a little less work can opt for fertilizers with more slow-release nitrogen.  Slow nitrogen products can be applied at 1½-2lb. of N/1000ft2 one time in the fall and will provide adequate nutrition throughout the season.
groSMARTLawnandGarden.com carries three products that are particularly useful for fall fertilization.
Nutriscape 22-0-11 is labeled as an “early fall” fertilizer but can also be used into late fall for sandy soils that benefit from more slow-release nitrogen.  Nutriscape 22-0-11 can be applied on both warm or cool season turf and provides more potassium than other fall fertilizers for soils that have tested low in K.  Plan to use 1lb. of fertilizer to provide 1/4lb. of N/1000ft2 or 4lb of fertilizer to provide 1lb. of N/1000ft2.
Nutriscape 32-0-7 does not have as much slow-release N as the 22-0-11 but the higher amount of N makes application on larger lawns or in larger amounts easier.  Plan to use 3lb. of fertilizer to provide 1lb. of N/1000ft2.
Earthworks 8-2-2  can be used for both warm and cool season grasses and is ideal for homeowners who prefer to use natural products.  It’s also a great product for sandier soils or soils without much organic matter because it is a composted product which, when used regularly will help to build organic matter in these soils.  Plan to use 6.26lb. of fertilizer to provide ½lb. of N/1000ft2.
*KEY TIP* Be sure to irrigate your lawn if needed this fall – Nitrogen can be lost if it isn’t watered in or if the turf isn’t growing because it’s too dry!
Fall Weed Control
Fall is also a great time of year to get a handle on some difficult to control weeds like clover, violet, ground ivy (also known as creeping Charlie), dandelion, and thistle just to name a scant few.
A “3-way herbicide” containing 3 or more different post-emergent broadleaf herbicides, like T-Zone will easily do the trick on most fall weeds and because it also includes triclopyr it works very well on clover, ground ivy and violets as well.
For a granular option there’s Nutriscape Lock-up 0-0-7 a “3-way” herbicide.  This product also contains potassium fertilizer and is applied with a spreader.  It works best when the grass and weeds are damp from dew or a light irrigation and when the product is allowed to dry onto the leaves.
If you’ve renovated or reseeded any part of your lawn this fall weed control is best left for spring.  Most herbicides can be damaging to new grasses whether seeded or sodded.  Be sure to read the herbicide’s label or talk with a groSMART.com professional if you have any questions about when or if a herbicide can be applied on a new lawn. 
Before you decide to apply an herbicide, properly identify weeds. A couple of hard frosts will kill some weed species, which means herbicide treatments are not only unnecessary, they’re wasteful. These weeds include broadleaf summer annuals such as purslane, knotweed and pigweed; and grassy summer annuals like crabgrass, goose grass, barnyard grass and foxtail.
Where practical, it’s best to apply herbicides directly to affected areas only rather than broadcasting the herbicide onto the entire lawn. Always read the label on an herbicide product before purchasing, before spraying and before cleanup.