Worm Food Guide

Worm Food Guide


Hey Worm People, 

We have a bunch of hungry worms, and we need to keep up with their voracious appetites for maximum growth and reproduction. That is why we are writing this guide. It will be a one-stop source for everything you need to know about feeding your worms.  This guide is a companion piece to How I feed Millions of Hungry Worms, check it out if you haven't already.

Feeding our worms is more complex than throwing a watermelon rind in the bin and calling it a day. Worms do love watermelon, but their nutritional needs are more complex. We need to meet their nutritional needs with each feeding while maintaining a healthy balance of heat, pH, and moisture levels.   

It is interesting to note that worms actually eat the microbes as they are decaying this matter rather than just eating the food directly - but in the end worms actually end up eating the food so most times we speak of it as "eating the food" for simplicity.

Before we chow down, we invite you to take our course Learn to Worm.  We poured hundreds of hours and years of experience into it, explaining the entire process of worm farming.  It will give you the knowledge you need for a healthy, thriving herd.  Sign up Today!

Captain Matt teaching worm farming basics in a Learn to Worm guide, standing in a worm farm with stacked trays and educational posters
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The anatomy of worm food 

Worm food combines nitrogen-rich fresh materials (greens) and carbon-rich dried materials (browns).  The safest way to manage your PH, temperature, and moisture levels is to balance these two with a ratio of 50 parts carbon to 1 part nitrogen (50:1 C:N Ratio). This will protect your worms from the potential anaerobic environment caused by overfeeding.  

Three important Macronutrients in worm food

  • Nitrogen: A key component in protein and nucleic acid development.  It's vital for growth and reproduction.  Nitrogen sources include fruit and vegetable scraps, coffee grounds, and manures.  
  • Carbon: Carbon is the building block of life.  It is important for energy and tissue development.  Carbon sources include cardboard, straw, leaf mulch, and egg cartons. 
  • Calcium:  Calcium is an important nutrient for a worm’s digestive health.  It plays an important role in tissue development and balancing PH levels in your bin.  Sources of Calcium are crushed eggshells, oyster shells, and agricultural lime.  

Five important Micronutrients in worm food

  • Phosphorus: Phosphorus plays a major role in energy transfer in the worm’s body.  Sources include fruit and vegetable scraps, and manures.  
  • Potassium: Potassium is important for keeping osmotic balance in the worm’s body.  It activates enzymes.   
  • Magnesium: Magnesium is important for metabolism and enzymatic reactions.  Sources include manures, plant materials and commercial supplementation.  
  • Iron: Worm’s need iron for the hemoglobin in their blood.  It comes from the soil, decomposed organic matter and can also be found supplementally in commercial animal feeds.  
  • Sulfur: Sulfur plays a role in protein synthesis.  Sources include manures, plant materials and kitchen scraps.  

Trace elements: Other trace elements include copper, zinc, manganese are needed in small amounts and are easily supplied in a well balanced diet.  

Grit 

Grit is an important component in worm digestion.  Worms do not have teeth.  They collect grit in their gizzards and it helps break up the food they eat.  

Importance of Grit 
  1. Digestion: Grit is what the worms use to break down their food, speeding up the composting process.  
  2. Keeps things moving:  Grit helps the worms digest their food and have it move through their bodies.  
  3. Nutrient absorption:  Grit increases nutrient absorption by allowing the worms to create smaller particles which promotes more microbial activity.    
Sources of Grit 

Some common sources of grit are sand, limestone dust, commercial poultry grit, crushed oyster shells, powdered eggshells, and rock dust.  

Four worm food considerations 

  1. Food Particle Size: The smaller, the better.  This can be more work for us, but it creates the best results and allows for easier monitoring of consumption.
  2. Food Freshness: Fresh to slightly overripe food is best. Avoid moldy or rotten food, as these may introduce unwanted pathogens.
  3. Avoid Overfeeding:  Overfeeding will cause your bed to become acidic, hot, and anaerobic.  All dangerous to your worms.  The general rule of thumb is to feed them what they will consume in two or three days.  
  4. Diversify Food Sources: The more variety, the better your worms' chances of getting all the above-mentioned nutrients.   

Worm Feeding Tips

  1. Always feed in one place so the worms can escape the exothermic heat caused by the decaying food.
  2. Bury your feed with a layer of bedding to avoid pest. Read more about bedding in our worm bin bedding guide and learn about the different pest in our worm bin pest guide.

Maintaining a Carbon and Nitrogen Ratio of 50:1

For every pound or kilo of greens added to the bed we need to add equal parts browns. This is a general rule that will help you maintain a safe balance in your bin. To get more specific you can apply this equation but we don't think its necessary.

(Green C:N Ratio x Weight of Greens) + (Browns C:N Ratio x Weight of Browns)= Ideal C:N Ratio (50:1)

Solving for Weight of Browns

Weight of Browns= (Ideal C:N Ratio - Green C:N Ratio(weight of greens))/Browns C:N Ratio

Assuming most greens are a 20:1 and most browns are 100:1. This equation equals approximately 1:1 by weight Greens to Browns.

Keep it simple for you and safe for your worms.

"When in doubt add Carbon" - Captain Matt

Common worm food questions 

What can worms eat from the garden?

Worms can eat a large variety of foods from the garden.  There are a few to avoid, and we will discuss them in the next question.  Leaves and stalks from your plants are excellent sources of nitrogen. Stalks can take longer to decay however, so keep that in mind. Here is a large list of fruits and vegetables your worms can eat from your garden: 

  • Grass clippings
  • Alfalfa hay
  • Clover
  • Wheatgrass
  • Excess foliage from lettuce plants
  • Corn stalks and husks
  • Tomato plant leaves (sparingly)
  • Apple peels
  • Banana peels
  • Carrot tops
  • Lettuce leaves
  • Potato peels
  • Cucumber peels
  • Pepper scraps
  • Bean scraps
  • Pea pods
  • Radish tops and scraps
  • Spinach leaves
  • Zucchini scraps
  • Squash scraps
  • Broccoli scraps
  • Cauliflower scraps
  • Kale leaves
  • Swiss chard leaves
  • Beet scraps and tops
  • Celery scraps
  • Sweet potato scraps
  • Turnip scraps and tops
  • Brussels sprout scraps
  • Collard green leaves
  • Pumpkin scraps
  • Asparagus scraps
  • Herb scraps (e.g., basil, parsley, cilantro, dill)

What can’t worms eat from the garden?

There are a few things to avoid in the garden. Some are poisonous and can hurt or kill your worms:

  • Treated grass clippings: Grass treated with pesticides or herbicides can be toxic to worms.
  • Diseased plant material: Can spread pathogens within the worm bin.
  • Oleander: Highly toxic, even in small amounts.
Picture of pink Oleander flower and leaves
Oleander: Image by hartono subagio from Pixabay
  • Black walnut leaves: Contain juglone, which is toxic to worms and many other plants.
Black walnuts and leaves
Black Walnut: Image by Hans from Pixabay
  • Rhubarb leaves: High in oxalic acid, which can harm worms.
Rhubarb stalks laying in grass
Rhubarb: Image by Alexander Fox | PlaNet Fox from Pixabay
  • Garlic and onions: Garlic and onions are harmful in large quantities due to their sulfur compounds.
  • Citrus peels: citrus peels contain d-limonene, which is toxic to worms and can cause digestive issues.
  • Daffodils: Can be toxic to worms.
  • Lilies: Can be toxic to worms.
  • Chrysanthemums (mums): Can be toxic to worms.
  • Hyacinths: Can be toxic to worms.
  • Foxgloves: Foxgloves are toxic to worms.

What can worms eat from the kitchen? 

Worms can eat a variety of kitchen scraps, providing them with essential nutrients. Here’s a list of suitable kitchen scraps for worms:

  • Fruit scraps: Apple peels, banana peels, melon rinds, avocado (without the pit), grapes, berries.
  • Vegetable scraps: Lettuce leaves, carrot tops and peels, potato peels, cucumber peels, bell pepper scraps, zucchini scraps, squash scraps, spinach leaves, kale leaves, Swiss chard leaves, broccoli and cauliflower scraps, celery scraps, beet tops and peels, pumpkin scraps, asparagus scraps, radish tops and scraps, turnip tops and scraps, collard green leaves, pea pods, herb scraps (e.g., basil, parsley, cilantro, dill).
  • Other kitchen scraps: Coffee grounds (and filters, if compostable), tea bags (ensure they are compostable and remove staples), crushed eggshells, plain bread (small amounts), rice (cooked, in moderation), pasta (cooked, in moderation), shredded newspaper (ink should be soy-based), cardboard (small pieces, no glossy print), egg cartons (shredded).

What can’t worms eat from the kitchen? 

Certain kitchen scraps should be avoided to maintain a healthy worm bin. Here’s what not to feed your worms and why:

  • Citrus fruits: Oranges, lemons, limes, and grapefruit contain d-limonene, which is toxic to worms. Their acidity can disrupt the pH balance of the worm bin.
  • Onions and garlic: All parts, including leeks and shallots, can be harmful due to their strong odors and acidic nature. They can also cause unpleasant smells and attract pests.
  • Spicy foods: Hot peppers and spicy sauces contain capsaicin, which can irritate and harm worms.
  • Dairy products: Cheese, milk, and yogurt decompose slowly, create unpleasant odors, and attract pests like flies and rodents.
  • Meat and fish: All types, including bones, decompose slowly, produce strong odors, attract pests, and may harbor harmful bacteria and pathogens.
  • Oily foods: Anything cooked in oil or greasy leftovers can coat the worms’ skin, suffocating them by blocking their ability to breathe through their skin.
  • Salty foods: Chips, salted nuts, and processed snacks have high salt content, which can dehydrate worms and disrupt the moisture balance in the worm bin.
  • Processed foods: Foods with preservatives and additives can harm worms and disrupt composting.
  • Pet waste: Dog, cat, hamster, or pet waste can contain harmful pathogens and parasites.
  • Plastic, metal, and non-organic materials: Do not decompose and can harm worms by creating blockages or releasing harmful chemicals.

How often should I feed my worms?

Feed your worms once or twice a week. If they finish the food quickly, you can increase the frequency. This is where the benefit of chopping food fine really helps. Do not add too much at once to prevent overfeeding.

How much food should I feed my worms? 

Worms can eat around half their body weight in food per day. Adjust the amount based on how quickly the worms consume the food.  A good rule of thumb is to feed them only what they can eat in one or two days and not to feed them until they have finished eating the older food.  

What if I overfeed my worms?

Overfeeding can lead to uneaten food rotting in the bin, causing foul odors, attracting pests, and creating anaerobic conditions harmful to worms. To avoid overfeeding, add food in small amounts and observe how quickly the worms consume it before adding more.  

How to Tell You Have Overfed Your Worm Bin

Overfeeding your worm bin can lead to several issues. Here are the key signs and steps to take if you suspect overfeeding:

Signs of Overfeeding

  1. Foul Odors: Caused by rotting food and anaerobic conditions.
  2. Unconsumed Food: Large amounts of uneaten food after several days.
  3. Fruit Flies and Pests: Attracted by excess food.
  4. Worms Trying to Escape: Indicating an unfavorable environment. 
  5. Wet and Slimy Conditions: Excessive moisture creates anaerobic conditions.
  6. Mold Growth: Indicates overfeeding and too much moisture.
  7. Decreased Worm Activity: Worms become sluggish and less active.

Steps to Remedy Overfeeding

  1. Stop Feeding Temporarily: Let worms catch up.
  2. Increase Bedding: Add shredded paper, cardboard, dry leaves, or other browns
  3. Improve Aeration: Gently turn contents to aerate and stir up any pockets of anaerobic conditions.
  4. Monitor Moisture Levels: Adjust by adding dry bedding or water.
  5. Remove Excess Food: Prevent further decomposition and odor issues.

Where can I find free sources of worm food? 

  • Local Grocery Stores: Ask for discarded produce. Preferably organic to avoid pesticides.
  • Coffee Shops: Collect used coffee grounds.
  • Restaurants: Request vegetable scraps. Provide your own bucket and make sure they don't add unwanted items.
  • Neighbors and Friends: Share kitchen and garden scraps. You could give them castings as a "thank you" gift.
  • Gardens and Lawns: Use grass clippings, leaves, and plant trimmings. People pay to have their leaves removed.
  • Breweries: Spent brewers grains are a good source but need to be composted first or mixed sparingly with other food.

What are the most common worm food mistakes?  

  • Overfeeding: Leads to odors, pests, and anaerobic conditions.
  • Feeding Harmful Foods: Citrus, onions, garlic, spicy foods, dairy, meat, and oily foods can harm worms.
  • Inconsistent Feeding: Worms need a regular food supply for optimal health.

Should I buy worm chow? 

Worm chow is a convenient supplement, providing a balanced diet. It also helps many worm farmers maintain consistent feeding when other foods are in short supply. However, it's not necessary if you provide a varied diet of suitable kitchen and garden scraps. See below for Captain Matt and other Worm People’s worm chow recipes.  

Can I feed my worms manure? 

Yes, but age the manure or compost it to avoid pathogens and excess ammonia. Suitable manures include rabbit, horse, cow, and chicken. Avoid fresh manure and manure from carnivorous animals.

Should I avoid certain manures? 

Yes, avoid pig manure in your worm bins. Here’s why:

  1. Pathogen Risk: Pig manure can contain a high number of pathogens, including parasites, bacteria, and viruses, which can be harmful to both worms and humans.
  2. High Salt Content: Pig manure often contains high levels of salt, which can be detrimental to worms, causing dehydration and disrupting the moisture balance in the worm bin.
  3. Ammonia Levels: Like other manures, pig manure can have high ammonia content, which can create an inhospitable environment for worms if not properly managed.

Can my worms eat duckweed?

Yes, according to this study at Rzeszow University , duckweed can be an effective source of nitrogen. If you have a pond outback and struggle to keep the worlds fastest growing plant at bay, you might be sitting on a good food source for your worms.

Worms love wheatgrass

Captain Matt has gone into great detail about his process of sprouting wheat grass to feed his worms.  Check out his YouTube video on the subject and like and subscribe.  Wheat grass sprouts are a cheap and nutritious source of nitrogen that your worms will love.  

Worm Food Tips from the Worm People Community Forum

I think we may have the best worm farming community on the internet.  If you haven’t joined it, you are missing out.  The Worm People Community is brimming with knowledge and wisdom and those who have it are eager to share.  We asked the community about their worm food and they answered.  Here are some awesome tips from some of our worm people. 

Melodie Kennedy

I use kitchen scraps…freeze first, take it out, unthaw it and put it in a blender. Then I put the food in an orchid plastic container and bury it. Worms can go through the slots to eat. Takes about a week for them to process. No outside material as it controls insects making there home in the bins. Worms are inside. The other two things they get is shredded cardboard and coco coir. Original comment.

We love the unique approach Melodie takes creating a little food cafeteria with an orchid container.  Simple and brilliant.  

James Carpenter 

I use powered up layer feed mixed with powdered egg shells mixed in a blender with water or water and non-citrus fruit juice mix ( cranberry or apple). I also just take fruit and veggies that are beginning to soften and rot and blend them to a liquid form. I store it all in ziplock bags in the fridge or freezer. They love it right out of there on these hot days. Original comment.

James makes a very good point to emphasize avoiding citrus.

LeSondra B. 

Worm chow (expired grains and oats), coffee grounds, egg shells, frozen food (fruits and veggies) that is semi thawed then blended chunky. Original comment.

LeSondra makes use of expired resources, and freezes everything before partially blending.    

They all freeze their food which is a great way to eliminate fruit flies and fungus gnats, break down the cell walls for easier digestion, and cool off the bin during the hot summer months.  

Thanks again James, Melody and LeSondra for sharing with everyone your process! 

Captain Matt’s Worm Chow 

We wrote down the recipe for you to follow. A printable version is available here.

Captain Matt's Worm Chow

Ingredients:

  • 1.5 gallons of chicken crumbles
  • 1.5 gallons of corn mash
  • 3 scoops (one per gallon) of agricultural lime
  • Quarry dust (very fine rock dust)

Instructions:

  1. Prepare Dry Mix:
    • In a large container (at least 5 gallons), mix 1.5 gallons of chicken crumbles and 1.5 gallons of corn mash.
    • Add 3 scoops of agricultural lime (one scoop per gallon of dry mix).
    • Add a sufficient amount of quarry dust to provide grit. Ensure the quarry dust is very fine.
  2. Mix Thoroughly:
    • Combine all ingredients thoroughly to create an even mixture. This dry mix forms the base of the worm food.
  3. Feed the Worms:
    • Take a portion of the dry mix and combine it with chopped vegetables or other green materials. Ensure the greens have been allowed to break down for two days to encourage microbial activity.
    • Optional: Add a small amount of something sweet (like a bit of fruit) to the mix, as worms tend to prefer sweeter materials.
    • Spread the mixture in a line or a small pile in the worm bin. This helps monitor worm activity and feeding efficiency.
  4. Adjust and Monitor:
    • If you have fewer worms, start with a smaller amount of food and adjust based on how quickly the worms consume it.
    • Check the bin regularly to ensure that the food is being eaten and to monitor the moisture and pH levels. Adjust feeding amounts as necessary.

The last bite

Feeding our herd safe, nutritious and cheap food is the most important variable in worm farming. Follow this guide to know the in's and out's of worm food. If you haven't taken Learn to Worm, we encourage you to sign up today. It will provide the knowledge you need to succeed in all of your worm farm endeavors.

Our Mission   

We are Worm people.  We do this for the love of worms but also the love of community.   We love sharing knowledge and growing as a group.  Our love for our little wriggly friends brings us all together. Through them we nurture our living soil.  Worm farming reduces waste in landfills and rejuvenates stressed, depleted topsoil. You are creating a healthier, biodynamic world. You are making a difference! 

Captain Matt smiling with his signature in cursive next to his photo