Getting the basics right of what to feed worms is vital to the success of a worm farm. This also includes what food is added, the quantity, preparation and placement in the bin. And if you do make a mistake, several worm farm problems such as a bad smell or a toxic environment can arise. So what do worms eat? Worms will eat anything organic. However, there are some foods you should avoid.
What Do Worms Eat – The Basics
Worms thrive on a balanced diet and prefer to eat their food as it begins to decompose. Keep a balance of green and brown foods.
Feed your worms fresh fruit and vegetable scraps. Limit foods high in acidity. Worms also don’t like strong flavors, such as citrus, garlic and onion. Be careful that fruit has no insecticides on it as this can kill your worms
Add egg shells. This helps to neutralize the pH levels in your worm bin. You can also add agricultural lime if needed. Egg shells are high in calcium as well which is beneficial to the worm farm. Feeding worms a lot of fruit will increase the acidity in the bin due to its the high sugar content.
Add carbon for bedding including shredded paper, egg cartons and cardboard. When in doubt, add more paper. Paper and cardboard should be shredded and soaked in water first.
Avoid feeding worms meat, dairy, and oils. While worms will eat meat and dairy products, these foods will create a bad odor and attract pests.
Don’t offer salty or spicy foods, or foods with preservatives. Worms breathe through their skin, and certain food can irritate that process
Add grains and grain products in moderation. Grains should be ground up before adding into the worm bin. Be careful not to add too much as grain may attract rodents.
Worm Farm Food List
Here’s a list of what to feed worms, and what not to feed worms:
What do worms eat? Add:
- Kitchen greens and vegetable scrapings
- Potato and other vegetable peels
- All fruit
- Crushed egg shells
- Shredded paper and cardboard
- Hair and nail clippings
- Cotton rags
- Grain and grain products
- Tea bags and coffee grounds
- Moldy bread
- Horse and cow manure, this is the worms natural diet and they thrive on it
Do not add (or avoid):
- Meats, bones, fat and anything oily or greasy – but natural oils (e.g. avocado) are fine
- Dairy products including butter, sour cream, milk, whole eggs (egg shells are OK) and cheese
- Canned sauces, peanut butter and other processed food
- Citrus foods like lemons, limes and oranges
- Pineapple contains an enzyme that will kill your worms
- Onions and garlic – although onion skins are OK in moderation
- Spicy foods such as hot peppers
- Yard trimmings treated with pesticides
- Plastic, metals, glass or other non-biodegradable items
- Paper that has a glossy finish or colored ink
- Poison ivy, oak or sumac or other poisonous plants
List of Bad Foods for Composting Worms
Here’s a list of foods to avoid when feeding worms:
|Grease and oils||
|Onions and garlic||
|Pineapple & Papaya (Pawpaw)||
|Rice and pasta||
Some bad foods such as bread are OK to feed to worms in small quantities, as long as you’re adding a relative amount of good foods as well. Moreover if you’re unsure about whether you should add specific food source, then always leave it out.
Worms eat about half of their body weight each day. However, when starting a new bin, this rarely happens straight away as they need some time to settle in. Your worms may take a week or two to adapt to the new environment, so don’t expect them to be 100% productive.
1000 worms is approximately 1 pound or 500 grams in weight. So if you have 1000 worms, you would need to feed them half of this weight each day (i.e. 1/2 a pound or 250 grams each day). Also be aware that worm populations will increase under favorable conditions given sufficient food supply and space. In very general terms, a Red worm population can double in number approx every 60 to 90 days.
Feed your worms once their last meal is nearly gone. Overfeeding worms is the single biggest cause of problems in a worm bin. If the bin contains too much food, the food scraps will begin to rot before the worms can digest them. In addition, this can lead to a toxic environment. It is better to underfeed your worms than overfeed them.
One way to prevent overfeeding worms is to add food scraps in small amounts and in one place at a time. Some people like to alternate sides when adding food scraps into the worm bin. Or they rotate adding food to different sections in the bin. For example, add food scraps to section 1, then a few days later repeat and add food scraps to section 2 and so on.
You should also consider the water content of foods that you add. Feeding too many high moisture foods such as zucchini and watermelon can cause a worm bin to become too moist.
Worms like to eat foods just as it begins to decompose. The rate of decomposition of organic materials is greatly influenced by carbon and nitrogen. For worm composting, conditions are generally ideal with a carbon-to-nitrogen (C:N) ratio of between 20:1 and 35:1.
Materials high in carbon (C:N ratio greater than 30:1) are categorized as browns because they are dry. And nitrogen rich materials are categorized as greens because they are fresh and moist (C:N ratio less than 30:1).
If you add equal amounts of greens and browns into the bin, then the C:N ratio should take care of itself. So it’s a good idea to have a basic understanding of what is a green or brown when adding food into the bin.
Here’s some estimated C:N ratios of various worm food sources:
- Garden waste 25:1
- Vegetable scraps 12:1
- Food scraps 15:1
- Manures 15:1
- Fruits 25-40:1
- Coffee grounds 20:1
- Grass clippings 20:1
- Fruit waste (e.g. banana skin) 35:1
- Peat moss 58:1
- Leaves 60:1
- Straw 75:1
- Shredded newspaper 175:1
- Wood chips 400:1
- Shredded cardboard 350:1
- Sawdust 325:1
Not only do you need an understanding of “what do worms eat?”. You should try and optimize worm farm food for their consumption.
Worms do not have any teeth. This means they need to wait until the food begins to rot or break down so that it is soft and wet enough for them to eat. So it’s good to cut up your food scraps into small pieces so that they can digest it faster.
There are a couple of other ways you can prepare food and make it easier for worms to consume. You can puree, grate, freeze, or microwave food scraps to help break down the material. And remember to make sure that food has returned to room temperature before adding it to your worm bin.
Cover new food scraps with a mix of bedding and paper or use worm blanket. This keeps it dark and moist, encouraging the worms to come up to the surface and feed. This will also discourage pests such as fruit flies.
Outdoor Compost Bin
Having both an outdoor compost bin and a worm farm work well together. For instance it’s better to add less preferable foods (e.g. harder and more acidic) into an outdoor compost bin rather than in a worm bin. And if you have more food waste than the worms can handle, then topping up the outdoor compost bin is a great option.