The cardinal rule for feeding composting worms is no meat, grease, or bones, which is the cardinal rule of composting in general. Adding these items will upset your bin culture, cause it to go anaerobic and stink, and invite unwanted guests.
Red wiggler composting worms are pretty easy going and will gladly eat all your kitchen scraps. If you’re not sure about a particular food, add it to a corner of the bin and see if the worms avoid it.
Best Worm Foods
The best foods for composting worms are from the produce aisle and soft foods which will break down quickly and easily in the bin. A short list of these foods includes:
- melon rinds
- banana peels
- celery stalks and leaves
- lettuce leaves and stalks
- onion peels
- potato peels
- broccoli stems
Worm Foods to Use in Moderation
- coffee grounds
- citrus peels
- cooked rice or pasta (no butter or sauce!)
- bread (nothing on it)
- corn husks
Save for the Outdoor, No Worms Bin
- avocado peels
- pits: peach, avocado or otherwise
- nut shells, sunflower seed hulls
- seeds: watermelon, squash
- corn cobs
Worm Food Treats
Sprinkle these on the top layer as a special worm treat:
- ground eggshells
The lists should give you an idea of what to add freely and what not to. The items in the moderation list are there because they contain compounds that could upset the bin environment. For example, coffee grounds are acidic and citrus peels contain an antibacterial agent in the citrus oil. Bread and pasta can clump up and cause the bin to go anaerobic.
Items on the outdoor list are tough, fibrous items that need lots and lots of time to break down, but break down they will. You can use these items in your worm compost if you are planning on dumping the whole shebang in your garden or don’t mind picking through the compost.
Also on the do not add to the pile list is pineapple. I recently learned, and tested the advice, that pineapple will kill composting worms. Indeed it does. If you have a very large bin, you might be able to get away with it, but be warned that it has been known to kill worms.
One of my favorite aspects of worm composting is that I don’t have to feel guilty about letting produce spoil in the refrigerator. It becomes worm food!