[Previously posted on Practically Gardening]
I had always tossed my orange and lemon peels into the compost bucket with the rest of my peelings. I never thought twice about it until someone said “Of course, you can’t compost citrus.” Of course? Why not?
Why You Shouldn’t Compost Citrus
I never really got a satisfactory answer to that question. Some said the oils would kill off the worms and beneficial organisms needed for decomposition. After all, citrus oils are often included in pesticides and bug sprays.
Others said it was because the peels themselves decompose so slowly, though I don’t know why that should be a deterrent. And some worried that they would acidify the compost.
Like most gardening rules, this one turns out to be false. (At least for now.)
While it’s true that citrus oils can effectively kill some insects, the oils tend to break down rather rapidly and leave the compost pile.
As for the worms, for some reason they don’t particularly like fresh citrus peels. The likely suspect is a liquid hydrocarbon called limonene. Worms don’t like it and it needs a specific bacteria to aid in its breakdown. Somehow these bacteria seem to show up when needed.
Compost goes through so many changes as it decomposes, the pH is rarely affected by any one ingredient. You needn’t worry about citrus making your compost too acidic. (The same is true of pine needles.)
As for their slow decomposition rate, that seems to be a myth too. Whole citrus fruits can take awhile to get started, because they are sealed in their rinds. A few punctures will fix that. And you can always tear the rinds into smaller pieces, to speed things up.
Is there a Limit?
Some gardeners are willing to admit that a little citrus in the compost is Okay (not great, but Okay), however too much will cause problems. Again, I’m not sure what those problems would be, but I could find no evidence that “too much” citrus will adversely affect your compost. Too much “green” material and too little brown will always cause trouble, citrus or no. But if you do a marathon juicing, don’t waste those peels. That’s compost in the making.
A Good Reason to Compost Citrus
There’s even an up side to composting citrus peels. Their initial strong scent acts as a deterrent to 4-footed scavengers.