Fall fertilizer is specially designed to stimulate the growth of new roots. It has a precise balance of potassium and phosphorous that helps nurture deep roots.
As such, it's important that you don't use leftover spring fertilizer at this time of year! Instead, choose a granular formula specifically for fall application. An ideal fall lawn fertilizer ratio is 12-25-12. (In other words, a high-phosphorus fertilizer.)
Fall fertilizer is specially designed to stimulate the growth of new roots. It contains a delicate balance of potassium and phosphorous designed to spur growth. This special blend allows the grass to “dig in” and prepare for the rough winter weather.
A: The blend of nutrients is usually different between fall and spring fertilizers, not to mention the other products that may be added. In your case, you also have a weed-killer in the unused fertilizer from last fall.
Don't let the term fool you. Winter fertilizers are applied in the fall in preparation for winter weather. A winter fertilizer, aka fall fertilizer (whatever you want to call it, really), is a great way to feed your lawn one last time before you put it to bed for the year.
Using a lawn food made for spring feeding will not harm your fall lawn, but it will not be as beneficial as a "fall and winter" lawn food that has more slow-release nitrogen.
Winterizer fertilizer also contains more potassium than regular fertilizer. The potassium is used to boost the grass's tolerance to freezing temperatures and enhance the root systems”. Winterizer fertilizer also feeds the grass throughout the winter. It even helps keep your grass healthy.
While this fall lawn fertilizer dose is important, an application at the end of October or early November is essential. At that time, apply a fertilizer with a formula of 13-25-12. The push of phosphorus will stimulate root growth through November and even into early December.
Apply fall lawn fertilizer once between August and November, right before winter hits, 6 to 8 weeks after the summer feeding. Apply the Scotts® Turf Builder® Annual Program Fall product now if you've been following that regimen.
Choosing a lawn fertilizer blend
A complete fertilizer with a high ratio of both nitrogen (N) and potassium (K) is essential for root growth, winter hardiness and disease resistance. An ideal fall fertilizer blend will have a nitrogen to phosphorous to potassium (N:P:K) ratio of 24-4-12.
Ideally, you'll want to mow and rake before fertilizing, so that excess lawn waste is removed and the fertilizer will have an easier time reaching the soil.
For fall feeds, it is important to use a fertilizer that has a lower level of nitrogen than the spring and summer feeds, but a higher level of potassium and phosphorous to encourage good root growth and general hardiness [such as this one from Amazon].
You should fertilize your lawn a day or so after a light rain or using a sprinkler. This prevents the application from being washed away. The moisture gets your soil damp and ready to receive nutrients. Do not apply fertilizer before or after heavy rains.
Nitrogen, phosphorus, and potassium take time to absorb into your soil. Doing anything too drastic on your lawn, such as cutting your grass, will disrupt this process. We always suggest to our clients that they wait 24 to 48 hours before mowing their lawn after fertilization.
When To Fertilizer Your Lawn in the Fall. The best time to apply your last fertilizer application is between August 15 and October 1. Ideally, your last lawn feeding should take place six to eight weeks before the average first frost in your area.
Fertilizing in the fall helps plants be hardier when the temperatures drop. We also recommend applying fertilizer in the late fall, toward the end of October or early November. This application will catalyze one last frenzy of root growth and really give your plants some staying power through the cold months.
Generally speaking, you should fertilize your lawn at least twice a year to ensure good overall health and keep your grass looking its greenest. But if you fertilize at the wrong time or over-treat your lawn, you could encourage weed growth, or possibly burn the grass.
The best time to apply winterizer is in late fall, about three weeks before the ground is frozen. This period will vary from region to region. In Canada, it will usually be two weeks before November while in other areas in the States the ideal time will be mid to late November.
We recommend waiting 24 hours after fertilizing to water your lawn, which will give the fertilizer time to settle. After the 24 hours are up, it's important to give it a good soak—not just a quick spritz with your hose—to activate the fertilizer and help the critical nutrients absorb into the soil.
A winter fertilizer assists and strengthens the continuously growing root system. The lawn will try to repair itself from damage done during the summer during the fall. Drought, heat and disease take quite a toll on the lawn and cause serious damage, so it is important to get extra carbohydrates to the root system.
You can usually apply most non-liquid granular fertilizers to wet grass, but not saturated ground. If there are ponds or heavy rain, it's best to wait until the ground processes the water before applying any type of fertilizer. If there's light rain, it's okay to spread dry granular fertilizer.
Instead of mowing and fertilizing on the same day, the best option is to mow your lawn a few days before or the day before fertilization. The benefits of mowing a few days before fertilizing are the same as mowing right before fertilizing: more even application, easier soil penetration, better absorption, and so on.
“I don't recommend fertilizing before or after a heavy rain because the fertilizer can be leached out of the soil or washed away before it can be consumed by the root zone,” Clarke says. Instead, the best time to fertilize the lawn is right before a light to moderate rainfall.
Don't apply winterizer too late—Generally, winter fertilizer should be applied in November or earlier, depending on your climate. Try to avoid applying in early December, as the nutrients within the formula may not take hold in time to protect the grass from the harsh conditions.
Fall Fertilizer Timing
For the majority of cool-season lawn owners, apply fertilizer anywhere from September through early November. The further north you garden, the sooner you'll feed your lawn. Fine-tune the timing for your locale by talking with your local extension service or garden center.