How Long Do Grass Cuttings Take To Compost?

As we take care of our yards throughout the growing season, we remove a considerable amount of waste. The grass clippings, leaves, and branches all add up quickly, especially when you collect them throughout the entire season. So, what should you do with them if you decide against burning them or tossing them in the trash (some landfills prohibit these materials)?

While branches are another story, you can actually compost grass clippings and leaves. But how long will grass clippings take to decompose?

Let’s find out.

What Is The Fastest Way To Compost Grass Clippings?

The quickest way to compost grass clippings is by leaving them on your lawn. The clippings will fully decompose in about three to four weeks, although they’ll no longer be visible in one to two weeks. At this point, they’ll break down enough to sink to the soil level, where they’ll be unnoticeable.

However, if you prefer to remove grass clippings from your lawn, you can always bag them for removal (or rake them when you’re done mowing). Once you collect the clippings, you can use them in your compost pile, where they’ll take one to three months to decompose fully.

Will Grass Clippings Compost On Their Own?

As mentioned, grass clippings will break down all by themselves when you leave them on your lawn. They break down relatively quickly here and save you the extra work of bagging the clipped grass. On top of that, leaving mowed grass on your lawn is excellent for your still-growing grass.

Grass clippings are packed with vital nutrients similar to a 4-2-1 fertilizer, which contains 4% nitrogen, 1% phosphorous, and 2% potassium. Since these are all essential nutrients your lawn needs, leaving the clippings behind after mowing can actually benefit your grass. Once the clippings break down, the nutrients they contain return to the soil, which aids in healthy blade growth.

So, if you don’t feel like composting your grass clippings (or don’t have a bag-style mower), you may want to consider leaving the clippings on your lawn.

How To Compost Grass Clippings

When you leave the clippings on your lawn, they’ll be visible for a few weeks before they begin to break down. When you mow every week, these clippings can start to build up and cause problems. While they don’t contribute to thatch, they can get stuck on top of thick thatch layers and take a long time to decompose.

So, you might decide to harvest the grass clippings from your lawn and use them for your compost pile. Here’s how to compost your grass clippings:

Mow Your Lawn

First, you need to mow your lawn. While you might be tempted to mow in the early morning hours, when the grass is still damp from dew, try to wait until the grass dries. This will make removing it from your lawn easier (unless you’re using a bag).

Before you start mowing, ensure your lawnmower’s blades are sharp, so you don’t damage the grass more than necessary. Set the blade height to remove roughly ⅓ of the grass height, but avoid taking off more than this. Generally, the ideal height for many grass types is about 2 inches, but this may vary based on your certain grass variety.

If you have a mower with a bag, attach the bag to the mower and cut your lawn. Otherwise, mow your lawn as usual.

Collect The Clippings

Some mowers don’t feature a bag-style design, so you’ll have an extra step in your process. You’ll need to collect the clippings and bring them over to your compost pile. Generally, the easiest way to harvest the clippings is by raking them into a pile. Once you rake them into a large pile (or smaller piles in each row), scoop them into a bag or wheelbarrow with a shovel.

Don’t worry about collecting every little blade clipping, as the scattered bits you leave behind will quickly compost and return their nutrients to your lawn.

Add Them To Your Compost Bin

Once you collect your grass clippings, haul them over to your compost bin. Before you add them, you’ll need to ensure you have plenty of brown material to add at the same time. Brown materials include dried brown leaves, newspaper, straw, and similar materials. Add a 50/50 mixture of browns and greens, as this should give you the correct 30:1 carbon-to-nitrogen ratio.

If you’ve recently treated your lawn with herbicides or other products, wait at least 14 days before adding it to your compost pile. You can let the clippings hang out in a wheelbarrow while they dry out, but be sure to wait the recommended time, as some herbicides might take longer to break down.

Once the grasses dry out and turn brown, they’re no longer considered greens. So, if you dry them out before adding them to your compost pile, add the following week’s fresh green clippings to balance out the browns.

When you add your grass clippings, avoid adding them all at once. Instead, layer the clippings with your brown material, which will help prevent clumps of soggy grass in the compost pile. These clumps can slow down the decomposition process, so it’s best to layer the materials to avoid these issues.

Keep The Pile Moist

Once you add your grass clippings and brown material, treat your compost pile as usual. Keep the pile moist, ensuring it doesn’t get too dry, as this can slow the decomposition process. Be sure to turn the pile regularly with a pitchfork or shovel, bringing the dry materials from the middle to the outer edge of the pile (rotate the outer edge in).

If you find any clumps of wet grass as you turn the pile, be sure to break them up as you work. This will help ensure the pile continues decomposing at a decent pace.

When Should I Not Add My Grass Clippings To My Compost Pile?

Grass Clippings in Compost Pile

Although adding your grass clippings to your compost pile is an excellent way to reduce the amount of waste you send to the landfill, there are times when it’s not the best idea. For example, if your lawn is diseased, you should avoid adding it to your compost pile. Doing so could spread the disease to other areas of your lawn and garden, creating a larger problem.

If your lawn is plagued by brown spot, rust, or fungus, throw your clippings away. Alternatively, you could burn the clippings but avoid transferring them to other areas of your lawn. Diseased lawn clippings aren’t good for your compost pile, so throw them away or burn them.

Frequently Asked Questions (FAQs)

Can I Use Grass Clippings As A Soil Amendment Or Mulch?

Yes, you can use your lawn’s clippings as a soil amendment or mulch. This is an excellent alternative to throwing the clippings away, especially if you don’t have a compost pile. To use the clippings as a soil amendment, work a few inches of clippings into the top layer of your garden soil (roughly 6 inches).

The clippings will slowly decompose in the soil, adding organic matter and nitrogen to your garden soil as they break down. These nutrients are essential for healthy plant growth, so this can be an excellent way to utilize your grass clippings.

On the other hand, you can also mulch the clippings. Once you collect the clippings, arrange them in a 2-inch-thick layer around a shrub or tree in your yard. The mulched clippings will help the soil moderate its temperature, retain moisture, and ward off weed growth. On top of that, it’ll add vital nutrients to the soil around the tree or shrub as it breaks down.

What Should I Do With Large Amounts Of Grass Cuttings?

If you have a large lawn, you’ll probably generate substantial amounts of grass clippings after each mowing cycle. So, what should you do with them? Depending on where you live, you might be able to bring your organic lawn and garden waste to a local recycling center or industrial composting center for free.

Of course, this varies based on location, so it might not be an option in all areas. If you don’t live in an area with these disposal centers, you can always use your grass clippings as mulch, soil amendments, or greens for your compost pile.

If you don’t have enough browns to balance the greens in your compost pile each week, consider saving one week’s clippings in a wheelbarrow to dry out. The following week, use the dried, browned grass clippings as your brown mixture, then layer them with your fresh grass clippings. Repeat the process throughout the mowing season, as you need brown material.