When Should You Mow the Lawn in Autumn?

As the leaves start changing color and the temperatures begin to drop, autumn brings a welcomed relief from summer’s heat. But it also signals that it’s time to start preparing your lawn for the winter ahead. Proper lawn care during autumn is crucial for maintaining a lush, healthy lawn next spring. One of the key tasks is deciding when and how often to mow your lawn in the fall months.

Why Mow in Autumn?

Mowing the lawn during autumn serves several important purposes:

Removes Fall Leaf Litter

As trees shed their leaves in autumn, all those falling leaves can accumulate quickly on the lawn. Too many leaves left sitting on the grass can block sunlight and cause bare spots and damage. Mowing helps mulch and shred the fallen leaves so debris doesn’t smother the grass.

Controls Unwanted Growth

Cool-season grasses like fescue continue to grow actively in autumn. Left unattended, the grass can get overly tall and leggy. Regular mowing curtails excess growth and keeps the lawn looking tidy.

Reduces Thatch Buildup

Thatch is a tightly intermingled layer of living and dead stems and roots between the green grass blades and soil. Some thatch accumulation is normal. But too much thatch can prevent water, air, and nutrients from reaching the soil and grass roots. Mowing often in fall can help reduce heavy thatch buildup.

Minimizes Pest Issues

Mowing frequently can help disrupt the life cycles of lawn pests like billbugs and chinch bugs. It removes the tall grass and debris where they like to hide and lay eggs. A well-maintained lawn is less hospitable to these unwanted critters.

When to Stop and Start Mowing in Fall

Cool-season grasses like Kentucky bluegrass and tall fescue grow vigorously in spring and fall. Warm-season grasses like Bermuda, zoysia, and centipede are dormant in autumn and don’t require mowing once they enter dormancy after the first frost.

Here are some general guidelines for when to mow cool-season grasses in autumn:

Continue mowing as long as the grass shows active growth and is still green.
Stop mowing once it has gone completely dormant after several hard frost or freeze events. This is usually sometime in late fall or early winter.
Resume mowing again in early spring after the grass greens up and starts regrowing.

The optimal stop and start time can vary depending on your climate, grass type, and local weather patterns each year. Pay attention to your lawn’s growth habits and mow accordingly.

How Often to Mow in Autumn

Mowing frequency in autumn depends on several factors:

Grass growth rate – Fertilizing and adequate rainfall in fall can spur rapid growth that requires frequent mowing to keep up.
Temperature – Cooler autumn temperatures gradually slow grass growth, allowing you to mow less often.
Leaf litter – Lots of falling leaves may necessitate weekly mowing to mulch leaves and prevent smothering the grass.
Last mowing – Time the final mowing in late fall about 4-6 weeks before the anticipated first frost in your area.

As a general guideline, plan to mow cool-season grasses every 4-7 days in peak fall growing seasons. Gradually reduce the frequency to every 7-14 days as growth tapers off in late autumn. Make the last mowing a slightly shorter cut around 2 inches to prevent disease issues over winter.

Mowing Height in Fall

Maintaining the optimal cutting height is key for lawn health. Follow these tips:

Cut no more than 1/3 of the total blade length per mowing session. For example, if the grass is 4 inches, don’t cut below 3 inches.
For the last mowing of fall, mow slightly shorter around 2-2.5 inches. This prevents fungal diseases and reduces snow mold.
For most northern cool-season grasses, mow at 3-4 inches all season long. Tall fescue can go up to 4 inches.
Some newer turf-type grasses can tolerate mowing as short as 1.5-2.5 inches if desired.
Always use sharp mower blades for a clean cut and minimal stress on the grass.

Fall Lawn Mowing Tips

Follow these tips for the best fall mowing practices:

Mow once grass growth slows to less than 1/3 inch per week. This minimizes stress on the grass.
Set mower blades to mulch leaves into fine particles so they decompose quickly.
Change mowing patterns frequently to prevent soil ruts and compaction.
Leave grass clippings on the lawn to decompose and provide free fertilizer.
Avoid mowing on wet grass to prevent clumping and blade damage.
After the final fall mowing, thoroughly inspect, clean, and service mowers before winter storage. Drain or stabilize fuel systems.

Proper mowing practices in autumn prepare your lawn for winter dormancy while setting the stage for a healthy, lush lawn next spring. Pay close attention to your own lawn’s growth habits and signs of dormancy. Time the last and first fall mowing accordingly to maintain just the right amount of autumn lawn care.

Frequently Asked Questions About Fall Lawn Mowing

Should I fertilize my lawn in autumn?

Fertilizing with a balanced slow-release formula in early to mid-fall can promote healthy grass growth before winter dormancy. But avoid high nitrogen just before winter, as it can spur growth vulnerable to frost damage.

How do I know when my lawn is fully dormant in autumn?

Cool-season grasses are fully dormant when growth stops completely and the leaves turn light tan or brown after several hard frosts. At this stage, mowing is no longer beneficial or necessary.

Should I dethatch my lawn in the fall?

Lightly dethatching in autumn can help remove excess thatch buildup before winter. But avoid aggressive power raking, as it can damage turf going into dormancy.

When should I aerate my lawn in the fall?

Early to mid-autumn is an excellent time for core aeration, allowing holes to fill in with new growth before winter. Aim to aerate when the grass is still actively growing.