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You’re enjoying a family cookout and have a ton of corn cobs left over. What can you do with them? Should you throw them in the garbage, or can you add them to your compost pile? Can you compost corn cobs?
Corn cobs can be safely composed and take about four months to break down entirely. Boiling and chopping the corn cobs ahead of time can help accelerate this process from months to weeks, though the longevity of corn cobs can also add valuable nutrition and mass to a compost pile.
Keep reading to learn more about how to compost corn cobs, the benefits of composting these tough kitchen scraps, and how to get the most out of corn cobs in your compost heap.
Can Corn Cobs Be Composted?
Corn cobs can be successfully composted. They are tough and fibrous but still capable of decaying and adding vital nutrients as well as bulk to your compost pile. Their bulk makes them ideal for breaking up the texture of a compost pile, and their slow decomposition rate can help nourish compost in the long run.
Corn cobs are not as tough as cherry pits and do break down over time. Their mass also adds more nutrition to your compost over a longer period, and corn cobs are uniquely designed to attract microbes and beneficial bacteria.
What Benefits Do Corn Cobs Add to Compost?
Corn cobs are woody and fibrous and add unique carbon deposits to your compost heap. The bulk of corn cobs can break up the structure of your compost heap, allowing air to circulate better and helping your kitchen waste compost faster.
Corn cobs in compost can also help balance out and feed beneficial bacteria in soil and to neutralize harmful substances and chemicals in soil.
The more air your compost gets, the more evenly everything will break down into usable fertilizer. Corn cobs tend to break down rather slowly, so their lingering size and density can help oxygenate a scrap heap.
This gradual breakdown means that your compost heap is still getting vital nutrition from the decaying corn cobs long after more delicate items have fully disintegrated. This is better for the overall value and healthiness of the fertilizer once you use it in your garden.
The small pockets left behind by corn kernels that have been eaten provide an ideal home for bacteria, mold, and beneficial insects. These creatures will help break down your compost better, and their solid waste can add nutrients back into the soil.
So how long does a corn cob break down in a compost heap?
Do Corn Cobs Disintegrate Quickly in Compost?
Raw corn cobs are heartier than other forms of kitchen waste. This is because they’re composed of a tough, wood-like core and, as a result, take longer to break down in compost than a potato peel, moldy tomato, or apple core.
How much longer? On average, a corn cob can take four or more months to break down fully in a compost pile. Outside of a compost pile, raw corn cobs can take over a year to completely decompose. This decomposition rate will depend upon the temperature of your compost pile, how frequently you turn the compost, and the lack or presence of hungry bacteria and worms within your compost.
Corn cobs are composed of three layers:
- Beeswing or Glume (the soft outer dimples in which kernels are housed)
- The woody ring, which supports the glume fibers and
- The pith which forms the toughest inner core of the corn cob
The last part of your corn cob to disintegrate into compost is going to be your pith, which will break apart faster when more heat, oxygen, and microorganisms are present.
The more you turn your compost, the more air your kitchen and yard waste will get, and the faster it will break down. The heat generated from rotting vegetables can accelerate this process, as can the bacteria and worms munching on and excreting decaying biomass.
Are there any ways to help speed up the composting process for corn cobs?
Boiled Corn Cobs Break Down Faster
If your corn cobs are the leftovers of a boiled sweet corn fest or a cookout where grilled corn on the cob was served, they’ll decompose even faster. You may notice that boiled corn cobs are more pliant than raw cobs, and this elasticity makes them easier on a compost heap.
The boiling or grilling process helps to break down further the fibers and structure of the corn cob, allowing it to decompose in weeks instead of months. They’ll still break down slower than other kitchen scraps but can add vital nutrients to your soil and are a great way to bulk up your compost heap.
Another simple way to help corn cobs break down faster is to chop them into halves or quarters. The smaller the corn cob piece is, the faster it will decay and the more heft you can get out of your scraps.
Adding moisture to your compost heap can also speed up the process and prepare your fertilizer for the garden. Be sure to water your compost heap in between layers, and rotate the material to keep it uniformly humid.
Additionally, you’ll want to ensure that your compost pile has a healthy mix of green and brown compost for maximum nutritional value and fertilization power.
Are Corn Cobs Green or Brown Compost?
Materials are either referred to as being “brown” or “green” in composting terminology. Green compost contributes to high levels of nitrogen and tends to decompose quickly. Examples of green compost would be
Brown compost tends to lend more carbon to the environment, breaks down slower, and includes
- Pine needles and
- Corn cobs
So corn cobs are a brown compost, which would work well to help balance out a compost heap rich in food scraps and mowed grass. While the ideal ratio of brown to green in a healthy compost heap is hotly debated, a ratio of “one part green” for every “one part brown” (50 / 50) is easy to remember and has been effective for many gardeners.
What about acidity or alkalinity? Will corn cobs make your compost more acidic?
Do Corn Cobs Make Compost Acidic?
Corn cobs are very mildly acidic in composition, averaging 6.5 pH. This can be important to know if you plan on fertilizing crops that respond better to acidic vs. basic pH environments.
Whereas some scraps and materials, such as orange rinds and coffee grounds, can cause the compost to increase significantly in acidity, corn cobs will add only mild acidity to your compost. Therefore, they will not affect the pH level of compost drastically. They will, however, release carbon for a longer period due to their sturdy structure.
Are there any risks involved in using corn cobs in compost? For example, will corn cobs attract wildlife to your compost heap?
Will Corn Cobs Attract Animals to Compost?
Corn cobs will no more attract or repel animals than any other compostable kitchen scrap. They’re a vegetable item and, as such, may be grazed or snacked on by the occasional mouse, skunk, deer, or porcupine who passes your compost heap.
They’re not especially attractive to animals, though, as they are tough, hard to chew even after being cooked, and are not very sweet or syrupy. Thus, they are perfectly safe to add to your compost heap and won’t attract any more animals than would broccoli.
Keep in mind, though, that as corn cobs tend to break down slower than other kitchen scraps, they’ll stay intact and visible to animals for longer. So when everything else in your compost pile has disintegrated, a corn cob or two may still be breaking down, which may be noticeable to passing wildlife.
This can be remedied by rotating your compost heap and keeping items that break down more slowly on the button, where they can decompose fastest and be less noticeable to passing animals.
Can I Compost Corn Husks and Corn Silk?
Corn husks and corn silk make for great compost, too. To accelerate the composting process, be sure to shred your corn husks into smaller ribbons to allow them to break up faster.
Like cobs, the husks of corn are quite tough, with an almost fabric-like strength, and ripping or shredding the husks can help them decompose at a similar rate to other kitchen scraps.
Corn silk, in contrast, is a fine, delicate waste product that breaks down quickly and will decompose at the same rate as less durable materials. Feel free to compost all of your husks and silk, and make sure to turn the compost regularly to help the husks break down fully.
Are there other uses for corn cobs around the yard or garden? For example, could you burn them on a bonfire or use them as indoor fireplace fuel?
Can Corn Cobs Be Burned?
Yes! Oh, yes. Corn cobs are excellent fire fuel and can even be converted into charcoal briquettes. Corn’s tough and woody interior makes it uniquely well suited for use as burn stock; corn cobs burn just as well in a bonfire as they do in an indoor wood-burning stove, as a free by-product of yesterday’s sweet corn dinner.
This makes them an attractive alternative for some to firewood, which must either be gathered or purchased. Using corn cobs as heating fuel can also reduce a home’s need for firewood, saving trees and natural resources in the process.
The ash from burning corn cobs can be disposed of, used as part of natural soap-making, or can even go back into your compost heap.
Corn Cob Ash is Great for Compost
Corn cob ash is excellent for your garden and can be shoveled back into your compost heap. There is evidence that traditionally burned corn cobs produced ash that is high in carbon and good for the soil.
So if you’ve already set your corn cobs on fire, the residue can still be added back to your compost and can still help your garden grow beautifully and bountifully. Ash adds bulk to your compost, as it does an excellent job of reducing odor, absorbing excess liquid, and making the rotting vegetable and plant matter less appealing to wild animals.
Finally, corn cobs can be used in creative ways around the garden if you don’t compost them all.
Can Corn Cobs Feed Wildlife?
Do you remember the pinecone bird feeders you may have made in Kindergarten? A similar use can be had for corn cobs. Simply smear a dried corn cob in peanut butter, roll it in seeds, and hand it from a low-lying tree branch in your yard.
You have a natural, environmentally friendly bird feeder in minutes which includes zero plastics or toxic elements.
Birds and squirrels can also nibble away at the meaty glume of fresh corn cob, and whole-cooked corn kernels make a much-appreciated treat for wild birds in winter.
Corn cobs can be composed successfully and take at least four months to break down completely in a compost heap. They are considered brown compost and decay slowly, releasing healthful carbon into the soil as well as oxygenating their surroundings. Corn husks and silk are also compostable, though husks should be shredded before being added to compost.
Corn cobs can break down in a matter of weeks if boiled, grilled, or chopped beforehand, and while they are not likely to attract animals, their longevity can be more notable to wildlife. As a result, corn cobs should be rotated to the bottom of a compost heap to reduce animal curiosity.
Corn cobs also make excellent fuel for a fire, and the ash from burned corn cobs can be added back into compost as a carbon-rich and absorbent fertilizer. Finally, corn cobs can be used around the garden as bird feeders, and fresh kernels can serve as wild bird food in winter.