How to Avoid Over-Feeding Composting Worms

If you are composting with worms, you need to feed them the right quantity of food scraps. How much food is too much? Over-feeding your composting worms can cause problems in the bin, including odors, acidity, excess moisture, pests and sick worms. What should you do to prevent and address these issues? Here are Uncle Jim’s guidelines for feeding the right amount of scraps to composting worms.

Quick Check: How Much Food is In There?

Dig around in the bin. How much undigested organic material is in there? The worms should start working on a feeding within a few days and finish it within 1 to 2 weeks. If you see large amounts of food, you are probably overfeeding. Under ideal conditions, worms can eat their weight in scraps per day. So if you have 1 pound of worms, you can theoretically feed them 1 pounds of scraps. However, we recommend you play it safe by feeding an amount they can handle every 2 or 3 days.

Over-Feeding Causes Odors

The most noticeable sign of overfeeding is a foul odor. Worm bins should have an earthy smell. If your nose is offended, your worm bin needs improvement. The worms’ job is to eat the food before it gets super-rotten and stinky. If you add too much food at a time, they cannot keep up. Too much food can also push the air out of the bin, leading to foul-smelling anaerobic decomposition.

If you are composting outdoors, this issue is less important than if you compost indoors. No matter the bin’s location, though, odors are a sign of trouble. Make sure that all food is buried at least 1 inch deep. Cut the food up small or use a food processor so the worms can work through it faster. Remove large chunks of food and any malodorous items. Whittle the scraps down to a couple of manageable pockets of food. Add oxygen by gently fluffing up the bin — use a hand fork, and be careful not to hurt the worms. Follow our Feeding Pattern below. If this does not work, see our detailed Worm Bin Smell Trouble-Shooting Guide.

Too Acidic

Sometimes a good worm bin goes bad because the worm’s habitat is too acidic. Acidic bins will have a terrible smell. Worms might seem sick and start to die. This situation can be triggered by too much food. The type of food you use makes a difference. You should not add large amounts of tomatoes, pineapples, orange peels, lemon rinds, etc. Acidic foods lower the pH of your worm bin. So do excessive amounts of grains such as wheat and cornmeal.

If you can measure the worm bin’s pH, aim for a number between 6.0 and 7.0. To reduce acidity, start by removing the lid. This allows airflow. Mix some shredded newspaper and/or pure dry peat moss into the bedding. Crush clean eggshells and add them to the bedding. Gently turn the bedding. And pray. Your composting program might be in peril.

Pests

Some amount of insect activity is normal in a worm bin. Composting is a natural process, and a few bugs will hang around the worm bin. Most of them harmlessly help break down the food. However, too much food can attract a noticeable and irritating population of pests. Outdoors, furry neighborhood pests might start munching — which isn’t an inherent problem, but it might bother you or your worms. Minimize this by burying the food and not feeding too much. If you have fruit flies indoors, see our Fruit Fly article.

Excess Moisture

Many kitchen scraps are watery, such as melon, zucchini, etc. If you add too much food, excess moisture can collect in the bin. The bedding should feel like a wrung-out sponge. If you can squeeze water out of a fistful of bedding, or if you see puddles, the bin is too wet. There are several possible reasons, but one reason is over-feeding.

Blot any puddles with paper towels or clean, dry rags. Remove watery foods. Check the drainage holes to make sure they are open. Mix in some pure dry peat moss or shredded newspaper to soak up some of the moisture. You can try running a fan over the bedding surface, but this may have a limited effect. Make sure rain cannot get in. See our article on Worm Blankets and Lids.

Recommended Feeding Pattern for Composting Bins

Start by feeding in one corner of the bin. Bury the food and cover it with at least 1″ of bedding. Wait a few days, then put the next feeding right beside it. Continue to work your way around the inner walls of the bin. By the time you get back to the starting point, the original feeding will be gone. This technique makes the food very easy for the worms to find, speeding the process. It also tells you how old each pocket of food is, so you can easily monitor the worms’ progress.

A healthy diet in the right quantity will keep your worms healthy and productive. Take care of your worms, and they will produce excellent organic fertilizer from kitchen scraps.