One of my frequent sources of material in my compost heap (I'm just getting into it lately) is kitchen scraps. My wife, bless her, has good intentions for eating more fruits and vegetables, but iffy execution, which means every few weeks, I wind up with moldy vegetables and fruits. I've been tossing them in the compost heap, burying them under some of the dryer materials, figuring that the heat is bound to kill off anything actively harmful, but I figured I'd get some input from others. I haven't noticed a bad smell from the heap, or large amounts of flies (although the deer seem to have decided the heap is an excellent buffet).

So, long story short, is it likely to be harmful to add moldy foods to the heap?

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    What do you think will happen to not-yet-moldy fruit in the compost heap? ;-) More generally: What's one of the main mechanisms of the process neatly and abstractly named "composting" ;-). Commented Jul 28, 2016 at 12:36
  • :) Slowly dessicate? I suppose that, as much as anything, I'm wary of creating a breeding ground. There's a difference between the sort of rotting you get in a refrigerator and stuff left outside. Commented Jul 28, 2016 at 12:40
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    Yes, outside is faster (in warm weather), and there are bigger animals :-). Commented Jul 28, 2016 at 12:41
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    A similar question was asked and answered on Sustainability SE: Are mouldy kitchen scraps okay to compost
    – THelper
    Commented Jul 29, 2016 at 7:54

3 Answers 3


Absolutely no worry at all. Moldy vegetables are already in the process of decomposition. Make sure you turn your compost regularly, moisten when necessary and add nitrogen. There used to be a kitty litter made from alfalfa pellets. SUPER nitrogen source and cheap.

NO MEAT, no poop from omnivores or carnivores only herbivores, mix green stuff and leaves and small twigs, or layer then mix. Lots of great articles and information on this site for you to read!

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    The "no meat" rule is probably not defendable. It's rather "not too much", and "will possibly smell", but it's by all means generally compostable. Why wouldn't it? Let alone poop. Commented Jul 28, 2016 at 12:42
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    meat on your compost can attract rats, which you really don´t want to have.
    – Julian
    Commented Jul 28, 2016 at 12:55
  • We don't eat meat, but we avoid putting any cooked food at all in, to avoid rats. We once had some who choose to nest in the compost itself. (Their ultimate fate was to become one with the compost.)
    – user15462
    Commented Jul 28, 2016 at 13:05
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    Anything that is still "food" will attract rats, raccoons etc. Compost piles with kitchen waste of any kind used to be illegal in urban areas prior to the 1950s because of vermin problems. The feces and urine of omnivores and carnivores will be a superior source of nitrogen. Better yet, they will drive away most vermin. If he's tossing fruits and high carb vegetables e.g. carrots, he will draw almost anything, including bees.
    – TechZen
    Commented Jul 28, 2016 at 13:43
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    My goodness, some of your ideas are wrong. Rats will eat ANYTHING. Doesn't have to be cooked. Cooked foods versus non cooked foods have nothing whatsoever to do with 'attracting' raccoons, rats, possum, mice, ravens (cool birds btw)...poop has ecoli bacteria, heavy metals and is not good for a compost pile unless you have anaerobic, high heat. But that doesn't help with heavy metals. Compost is NOT meant to be a fertilizer. Far better sources! Compost is decomposed organic matter to FEED YOUR SOIL ORGANISMS! Feces and urine WILL NOT DRIVE AWAY rodents!!
    – stormy
    Commented Jul 28, 2016 at 20:37

The types of mold that would grow inside a modern hermitically plastic sealed house or a refrigerator, won't last long out doors. I would have some concern about having them in the house. We had a large piece of fruit, a melon I think, "escape" into a notch of bookcase somehow. Half the family came down a violent allergy apparently from the spores that grew off and then got endlessly circulated through the houses closed and insulated system.

If you're worried about global warming though, putting anything with readily available free sugars into a low oxygen mound of digesting bacteria will produce a much higher ratio of methane to CO2. Methane is 100 times as powerful a greenhouse gas than CO2 although it degrades more quickly. Producing more methane today will have a greater long term impact than the equivalent CO2. Some large installation that compost, e.g. vineries separate out high sugar items into fermentation vats were the decomposition produces CO2 instead.

  • Moldy fruit versus mold between the outside wall and the inside wall of a structural wall of one's home is COMPLETELY DIFFERENT. I agree that methane is more powerful than CO2, but the amount you are talking about is a non-issue. CO2 is a non-issue. Water vapor is the largest worry with green house gases. Our media and their owners are dumbing down even the smartest people in our society. AGAIN, CO2 is a non-issue. Anthropomorphic global warming is a LIE. Complete lie. Check out scientists that do not rely on federal grants to explain the facts. Climate change is the norm, natural...
    – stormy
    Commented Jul 28, 2016 at 20:58
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    You might note that anthracnose is a common fruit rot pathogen (including on grocery store produce, such as peppers and tomatoes, in the refrigerator). Supposedly, you shouldn't compost stuff with anthracnose (but because many gardeners probably do compost stuff with anthracnose without realizing it, I don't imagine it's as big of an issue as some articles might have you believe, even if it is an issue). I suspect that killing the pathogen with heat isn't as important as having it be outnumbered by other microbes. Commented Sep 14, 2017 at 10:53

If it is organic it goes back to the earth. Mix soil with the compost to get worms started. Move the location of pile often.

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