The Late-Fall Fertilizer Application Golf Courses Swear By

If I could only fertilize a cool-season lawn once a year, I wouldn't do it in spring. I'd do it in late fall, right around the last mowing. On the golf course this was one of the feedings we never skipped, and it's the one most homeowners have never heard of.

What the late-fall feeding does

By November the grass has mostly stopped growing leaves. But it hasn't stopped working. The roots keep growing as long as the soil isn't frozen, and the plant is still making food in its green leaves on mild days. Nitrogen you put down now doesn't go into a flush of top growth you have to mow. The plant stores it.

That stored food pays off three ways:

• Earlier green-up in spring, often weeks ahead of the neighbors, without the big spring flush that a heavy April feeding causes.
• Better root growth through late fall and early spring.
• Better color into early winter and a lawn that comes through the cold with more reserves.

This applies to cool-season grasses: Kentucky bluegrass, tall fescue, perennial ryegrass and the fine fescues. If your lawn goes brown and dormant in winter, this is your feeding.

When to apply it

The target is after the last mowing of the year, while the grass is still green. Purdue University's turf program puts this application around or just after the final mowing, and lists September and November as the two best times to fertilize a cool-season lawn.

In practice, that's somewhere between late October and late November across most of the northern US, earlier in the far north and in the mountains, later near the coasts and the big lakes. Watch the grass, not the calendar. If it's still green and the ground isn't frozen, you're in the window.

Don't apply it to frozen ground or right before a heavy rain. Fertilizer on frozen soil can wash off into the street and the storm drain instead of into the root zone.

How much

Purdue's guidance for the late-fall application is 1.0 to 1.25 pounds of actual nitrogen per 1,000 square feet.

To turn that into product, divide by the first number on the bag. A 46-0-0 urea is 46% nitrogen, so about 2.2 pounds of product puts down 1 pound of nitrogen per 1,000 square feet. A 32-0-4 product would take a little over 3 pounds per 1,000 square feet. Measure your lawn once, write the square footage on the garage wall, and you'll never guess again.

What product

For this feeding, a quick-release (soluble) nitrogen like urea works well, because the grass needs to take it up while it's still active. Slow-release products are great in spring and early fall, but much of their nitrogen may not be released until the soil warms up next year.

Skip the phosphorus unless a soil test says you need it. Many states and towns restrict phosphorus on established lawns because it washes into lakes and streams. Most lawn fertilizers sold today already show a zero in the middle. If you haven't had a soil test in a few years, fall is a great time to do one; see our guide to reading a soil test report.

How to apply it

1. Calibrate or check your spreader setting for the product on the bag. When in doubt, set it lower and go over the lawn twice in crisscross directions. You'll avoid stripes.
2. Sweep any granules off the driveway, sidewalk and street back onto the grass. That's fertilizer headed for the storm drain otherwise.
3. Water it in lightly if no rain is coming, or apply ahead of a light rain.

Common mistakes

• Fertilizing a dormant brown lawn. If the grass is already brown and asleep, it can't take the nitrogen up. You're too late; wait for spring.
• Doubling up "for winter." More isn't better. Excess nitrogen in late fall can feed snow mold. Stick to the rate. See our piece on snow mold.
• Skipping the September feeding and trying to make up for it now. The two applications do different jobs. The early-fall one builds the plant; the late-fall one stocks the pantry.

If you want the whole year mapped out, our guide to building a professional-grade fertility program lays out every application. But if you only add one thing this year, make it this one.

Sources (2)

Purdue Extension, Fertilizing Established Cool-Season Lawns (AY-22); Purdue Turf Tips: Fall Fertilization.

Related: When to Stop Mowing for the Season (and How Low the Last Cut Should Be)