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Lawn Mowing

Leaving grass clippings on your lawn improves turf, saves you time and reduces disposal of yard waste.grass

This page covers:

The lowdown on mowing
• Lawns are healthiest when mowed at a height of 3/4 to 11/4 inches, and clippings are left on the lawn.
• Mow frequently so no more than 1/3 of the grass is removed at one time. This may mean mowing every five days.
• Apply approximately one pound of fertilizer per 1,000 square feet of lawn in the fall when soil is moist, but not during a heavy rain. Use a product containing about 1/3 quick release and 2/3 slow release fertilizer to limit growth and leaching losses.
Late season fertilization favors root growth. Fertilizing in the spring means more frequent mowing  (up to twice per week) and can produce a weak, poorly rooted turf.

Total annual application of fertilizer shouldn’t exceed four pounds per 1,000 square feet for a moderately maintained lawn. Slow-release fertilizers are best because they gradually make nutrients available.
Most of our soils in Whatcom have sufficient phosphorous for grass, so choose a low- or no phosphorous fertilizer for your lawn.
• Treat your lawn with chemicals only when necessary. Using pesticides can kill beneficial earthworms and microorganisms that break down clippings and digest thatch-causing dead stems and roots.
• Let shredded leaves remain on your lawn to decompose and add nutrients. Most mowers will satisfactorily shred a thin layer of leaves. If the shredded leaves cover your lawn too thickly, rake them for use as mulch or compost.


Leaving grass clippings on your lawn means:

No bagging and no hauling, and more time to enjoy your lawn!lawn mower

More nutrients for your lawn –naturally!

Less garbage to throw away – a savings on your trash bill!

A healthier lawn rich with beneficial organisms!

Lower fertilizer costs!

Mowing your lawn

• Various types of mowers are available on the market. Each has its own advantages and disadvantages. Rotary mowers are most commonly used for grasses mowed higher than one inch. Many rotary mowers can be operated with or without the bagging attachment. Bagging mowers may or may not require the bag to be attached while in use. Kits are available that will convert some bagging mowers into mulching mowers.
• Mulching mowers, a type of rotary mower, finely chop clippings. This allows clippings to break down faster on your lawn. Mow often: if grass is too tall, you can’t use your mulching mower.
• Push mowers are quiet during use and require no fossil fuels to operate. They are a good choice for a small lawn. Drawbacks: Push mower blades are harder to sharpen and won’t mow taller grass effectively.
• Mow regularly regardless of mower type. Keep the blade sharp and properly adjusted. Dull mower blades use more gasoline, give the lawn a frayed appearance, and can allow leaf diseases to start.

Why quit bagging grass clippings?

Q: Bagging is needed for a quality lawn, right?
A: No. A lot of people with great looking lawns don’t catch clippings when they mow. In fact, lawn researchers have proven that leaving clippings results in a healthier lawn that is less prone to disease. Clippings contain organic nutrients that are returned to the lawn when left to decompose.

Q: My lawn is healthy and I bag my clippings. Why shouldn’t I continue bagging?

A: If you mulch with your grass clippings, or compost them and use the compost, that’s fine. But you’ll spend more time bagging and hauling the grass to your compost bin than you will leaving clippings on your lawn. Putting grass in your garbage costs money on your trash bill and burdens our community’s garbage disposal system. Leaving clippings on the lawn avoids these problems.

Q: But clippings cause thatch, don’t they?

A: Grass clippings break down quickly and don’t cause thatch if grass is mowed regularly. The brown, spongy material we call thatch starts with thick grass stems and roots. These grass parts break down slowly and can accumulate as a thatch layer, especially with our cooler soil temperatures and slower microorganism activity. Dethatch your lawn every one to three years with a dethatcher or power rake.

Q: What if my lawn has a lot of weeds? Wouldn’t leaving clippings increase the problem?

A: Not necessarily. Continue leaving clippings until you’ve consulted with a WSU Extension agent or a Master Gardener about dealing with weeds in your lawn.

lawn mower blade
Other uses for grass clippings

Mulching reduces weed problems, moderates soil temperature, and retains moisture. Mulch also helps maintain good soil structure and minimizes erosion by protecting the soil surface.

If you need to rake your grass clippings, use them as a mulch by spreading them very thinly (no more than 1/4 inch deep) in your garden or planting beds.
Check periodically to ensure clippings haven’t matted. Matted clippings can harm desirable plants by causing water to run off instead of soaking into the soil. Also, don’t harm your plants by mulching with grass that has been treated with weedkillers. Be particularly cautious if using long-lasting herbicides.
Chemically-treated lawn clippings should be left on the lawn or in your compost bin, where most herbicides will break down in about six weeks. Do not compost clippings treated with long lasting herbicides; leave them on your lawn.

Another option for grass clippings or leaves gathered by raking or bagging is to compost them for use in your yard and garden.
Learn more about home composting from a volunteer Master Composter. For information, call (360)676-6736.

Click here for a printable brochure containing the information on this page.
(For best results, print double sided on 8.5"X14" paper.)



Contact Us

Whatcom County Health Department, Solid Waste Division
509 Girard Street, Bellingham, WA 98225; (360) 676-6724