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How to Fatten Compost Worms

Whether you’re using your compost worms for fishing or selling the worms to gardeners, fat worms are most desirable. Fattened compost worms are evidence of healthy feeding and high-quality compost. You can use a variety of commercially made worm food blends to fatten up your compost worms, particularly the “worm chow” blends that are high in protein. You can also make your own worm-fattening food using a simple recipe and modifying your worms’ food-scrap diet.

Feed your compost worms lots of green vegetables. Limit starches and highly acidic fruits and vegetables.

Place 12 egg shells into a blender. If you’re using egg shells from cracked raw eggs, be sure to rinse the shells well in warm water and let them dry. Blend the egg shells until they’re pulverized into a powder.

Add 2 cups of oatmeal and 1 cup of cornmeal to the blender. Blend the cornmeal and oatmeal with the pulverized egg shells.

Sprinkle the mixture on top of your compost until you’ve created a thin layer. Mist with water and cover your compost bin. If you usually leave your compost uncovered, spread a layer of moistened newspaper over the grain mixture.

Worms Aren't Eating My Compost?

One pound of worms can process about only 1/2 pound of food scraps daily. Gradually increase the amount you provide until the worms can work through the majority of it in one or two days. They also often won't eat potato peels or large amounts of bread, although those foods are not dangerous to the worms. Oil, dairy products and meat invite pests to the compost bin, and those food items are often left uneaten. Worms also may have food preferences. Adding food scraps properly to the compost bin helps encourage the worms to consume all of the food. Keep the bin as moist as a wrung out sponge, and avoid adding large amounts of overly wet food items to the bin.


Feed your compost worms a thin layer of the grain-and-eggshell mixture three or four times per week to fatten them. Be sure to keep the compost moist by misting with water or applying moist newspaper every time you add the feed mixture.


Don’t feed your compost worms too much coffee grounds. This will raise the acidity in the compost bin and cause your worms to stay thin.

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