How to Tell If Your Compost is Ready To Use: 5 Expert Tips
Compost converts old waste into a nutrient-rich soil amendment perfect for the home garden. If you made a pile months ago and wonder if you can use it this spring, these five expert tips from composter Jerad Bryant will help you sort it out.
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Composting is an exceptional method for recycling waste. You can convert any organic matter into compost, including garden waste, kitchen scraps, and fallen leaves. Halve your monthly waste volume by diverting all your potato peels, spoiled veggies, and vegetable scraps to an outdoor pile.
Compost is like a gardener’s way of mimicking natural processes. In forests, meadows, and natural spaces, debris builds up on the floor. Over time, worms, fungi, bacteria, and other soil organisms convert the debris into rich, porous, and moisture-retentive soil.
So, how do you tell when your compost is ready, and how long does it take? Let’s find out!
Bokashi Kitchen Compost Bin 2.5 gal.
Bokashi Kitchen Compost Bin 2.5 gal.
How Long Does Compost Take?
Compost can take anywhere from three weeks to a year to fully decompose. It depends on how large the pile is, what kind of compost it is, and how hot or cold your local temperatures are. There are two main types of piles: hot and cold.
Hot compost requires more maintenance than cold compost, though it’s quicker! It’s a perfect method for the spring, as it’ll convert your lawn clippings, garden debris, and spent annuals into humus-rich soil. Humus is a particle that’s absorbent and nutrient-rich—it’s a necessary component for healthy soils.
Cold compost takes three to six months or longer to break down. Its breakdown depends on the daily temperatures and how often you turn and water your pile. Though it’s a slow process, it’s low maintenance and perfect for gardeners with lots of debris.
Composting is quick when it’s warm and slow when it’s cold. Insulate piles during the winter to have them continue breaking down, and shade them in the summer to prevent them from drying out.
How to Make a Compost Pile
The easiest way to repurpose organic matter is with a pile—all you have to do is stack your debris in an area that’s three square feet or larger. You’ll layer carbon-rich waste, or browns, with nitrogen-rich debris, or greens. Use this chart to help you determine which is which.
| Carbon-Rich Browns | Carbon:Nitrogen Ratio | Nitrogen-Rich Greens | Carbon:Nitrogen Ratio |
| Fallen leaves | 30-80:1 | Kitchen scraps | 15-20:1 |
| Straw | 40-100:1 | Fleshy plant waste | 15-25:1 |
| Wood chips and sawdust | 100-500:1 | Grass clippings | 15-25:1 |
| Chemical-free paper products | 150-550:1 | Manure | 5-25:1 |
To work properly, a careful balance of greens and browns is required. You’ll want to add one shovelful of greens for every two to three shovelfuls of browns. This carbon-to-nitrogen ratio ensures the pile never turns rotten, dry, or unbalanced.
After stacking up the materials, some aftercare ensures the waste breaks down properly. Maintain consistent moisture so that it’s moist, but not soggy. Turn the piles daily in hot composting systems and once a month for cold ones.
Other Ways to Compost
Making piles isn’t the only way to compost—there are dozens of ways to recycle organic matter! Tumblers, Earth machines, and Bokashi systems are some of the many ways. Use whichever method works best for you and your garden.
Trench composting is a unique method where, instead of making piles, you bury the debris underground and let it decay. Bury it a foot or deeper in the soil, and plant nutrient-loving plants on top.
If you’re using tumblers, add water consistently to keep the debris moist inside. Or, try other methods like sheet composting, vermicomposting (using worms), and trench composting.
5 Ways to Know If Compost is Ready to Use
Finished compost looks the same regardless of the method you choose, and it’ll be easy to look for the signs. Let’s check the particle size, the color, and the smell to see if your compost is decayed and ready to use.
Check the Particle Size
One easy way to know is by how large the particles are. When you first add waste to the pile, it’s full of large chunks, pits, and clumps. As the worms and microorganisms break up the chunks, they grow smaller and more uniform overall.
Turn the pile with a pitchfork and look at the particles. Are they small and uniform, or are there still large, undecomposed chunks? Leave it be if they’re all different sizes.
Instead of waiting, you can separate the small pieces from the undecomposed larger ones. Using a mesh screen or sifter, sift the components through it so the small, broken-down pieces fall into a bucket below. Use the sifted compost, and place the large chunks back in your pile to break down further.
Watch for Large Chunks
Chunks may form from the large, decomposing particles. Soggy, mushy debris sticks together, creating clumps of waste that worms love to tunnel into. These clumps are less than ideal in the garden, as they’ll attract pests that wreak havoc on your plants.
To help speed up their decomposition, use your shovel or pitchfork to break the clumps into smaller pieces. The smaller the clumps are, the quicker they’ll decompose into humus-rich soil.
If you see tons of critters inside the mushy chunks, consider leaving them as is to avoid hurting the worms, beetles, and wormy fly larvae. Place the mushy parts in the center of the pile, as the warm, insulated center is where decomposition works the quickest.
Monitor the Color
A quick color test, alongside the other techniques, is a great way to rate your compost’s readiness. The entire pile should look the same—there shouldn’t be different waste items of different colors. You want your pile to look black-brown and crumbly,
A light brown color may indicate that it needs more moisture, while a deep, rich black may indicate sogginess. Ensure the compost stays 50% moist, like a wrung-out sponge, so that it decays as quickly as possible.
If you’re using the cold composting method, you may want to peel back the top layers to inspect the color inside. In cold, slow systems, the outer layer often requires more composting, while the innermost layer decomposes rapidly.
Notice Shrinking Piles
As microorganisms, worms, and other soil critters eat the waste, they break it into tiny particles. You’ll notice your composts shrink in size throughout the process. They’ll shrink from a third to a half in size! Do not panic; this is a normal step in the composting process.
As the composts shrink, you may want to add more debris to them to fluff them up. You can do this, though you’ll extend the time the piles need before they’re available to use. Avoid adding new debris if you want to harvest it soon.
One ingenious way to manage incoming waste is to have two or three piles instead of one. You can use one when it’s done and add to the other; that way, you can continue recycling organic matter while also having a free soil amendment to access.
The Smell Test
The final tell that composts are ready is their smell! This may not be the test for you if you’re squeamish, but if you want to be sure it’s a good idea to put your nose to the challenge. Sniff the piles’ interiors to see how earthy or rotten they smell.
If the aroma is pleasant, earthy, and rich, the amendment is likely okay to use. If it smells like kitchen scraps, grass clippings, or anything you’ve put in it, then it may need more time to decompose.
Frequently Asked Questions
What should you do when the compost is ready?
You have a few options! Fill your containers, mulch your garden beds, or amend old potting soil. This nutrient-rich soil amendment works well throughout the garden.
How long do I have to wait before the compost is ready to use?
Hot compost is ready in three weeks or longer, while cold compost takes anywhere from three to six months.
When is compost ready to add to the garden?
It’s ready when it’s black-brown, crumbly, and earthy in smell. The particles should be small and uniform throughout, and there shouldn’t be any chunks.
