Is there any kind of food scrap that shouldn't be composted?

[claudine]

I was told to avoid citrus peels because we add worms to our compost bin. My uncle who has a worm farm told me that the oils in the peels can kill the worms. I learned a trick where you can add lemon peels and ice cubes to your garbage disposal to clean it and I have been doing that with them ever since. It makes your whole kitchen smell awesome at the same time.

This sounds like a wonderful idea, thank you for sharing it. I will definitely give it a try. The smell of lemons is really pretty and refreshing, I love it
As for worms, I don't add any to my compost bin, but I'm pretty sure there are a few of them in it anyway and I wouldn't want to kill them.

 

[headfullofbees]

I won't compost any alliums susceptible to rust, like garlic or leek leaves.

 

[starshinesis]

I had never heard to not compost citrus peels. I will have to check more about that. Very interesting. I would suppose that it would only affect it if there were a lot of them. I've heard about putting them down the garbage disposal though.
Any bread products should not be composted. These also attract pests. Cooking oil or anything with cooking oil on it smells like food to those unwanted pests. If a plant is diseased don't compost it. The disease may transfer to others when you use the compost. Cooked rice attracts the wrong microbes. Don't use sawdust unless you know it is untreated wood. Walnuts contain a substance that isn't good for the compost bin.
Something many people don't realize you can compost are tea bags and coffee grounds including the filter.

 

[ChanellG]

Basically nothing with fat should be composted, and by fat I mean butter and oil.

How about citrus peels? I read somewhere that it's better not to compost them, because they lower the activity of microorganisms in the soil. My friend, who knows a lot about gardening, says that it's not true though. It's confusing
Do you add citrus peels to your compost?

Claudine, I compost citrus peel if I don't use them for cooking before they go bad and it doesn't seem to be a problem for the worms. My plants also grow just fine when I mix it in to their soils. I also compost onion bits and avocado pits. I think a lot has to do with where you live and the method of composting you use.