Feeding Composting Worms

There are 2 classifications of organic matter (food) in a worm composting context; Bedding and Food.

Worms eat both, but bedding is more to provide stable and healthy conditions in the bin, while food serves the purpose of nutrition.

An easy way to estimate if something is more similar to bedding or more similar to food is to imagine the organic matter placed in a ziplock bag and left in the sun.

If it's going to look all nasty and moldy and smelly, it's likely a "food." If it's more or less going to look the same, it's likely a bedding.

Bedding is organic matter that is rich in carbon, low in nitrogen, and, like a sponge, has a high capacity to hold water.

Bedding holds water to keep the worms hydrated, but also leaves space open for oxygen exchange.

In the classic composting world, these are generally the same as "brown" materials.

Examples of Worm Bedding Include:

1. Shredded Cardboard

2. Shredded Paper

3. Fall leaves

4. Coconut Coir

5. Straw

6. Finished Compost

7. Aged Manure

8. Saw Dust

9. Finished Worm Castings or Vermicompost

When you start, you should have at least 1-2 square feet, with 3-4 inches deep of bedding, hydrated to about 60-80% saturation for every pound of worms.

Over time as you add food you may notice that your bin is starting to get wet from water rich food (most fruit/vegetable waste is 90% water), additional dry bedding should be added to soak up excess water and restore balance to the air/water relationship in the bin.

Bedding is a fix-all for worm bins. Use it as much as you want, and whenever you come across almost any problem in the bin it can be solved by adding fresh bedding.

So start with 100% bedding, and then add as needed to keep your bin around 60-80% moisture.

1. Identify which bedding materials are locally available, and ideally free to you.

2. Be aware of the strengths and weaknesses of those beddings (shredded paper will clump together and restrict airflow, fall leaves don't hold as much moisture as others, etc.)

3. Create a mix of beddings that will compliment each other and create a nice spongey feel bedding.

4. Get them to an appropriate moisture level - only 1-3 of drops of water should come out when you squeeze it with your hand. I typically do this by soaking it in a bucket of water and then squeezing out the excess.

5. Add it to the bin! (3-4 inches deep or more)

Or if you don't want to make your own bedding, you can get some from me! I recommend Coco Coir as it comes with instructions on how much water to add, and it works as a single-ingredient bedding.

But if you do make your own, remember that bedding needs to be high in carbon and allow for airflow while maintaining appropriate moisture levels. Individual bedding materials may not be sufficient on their own, and will need to be mixed with others.

Remember, a sponge-like fluffy texture is the goal.

Organic Matter that is higher in nitrogen, and typically has a higher moisture content, like fruit and vegetable waste, coffee grounds, etc., is considered food.

These are the primary source of nutrients for your worms and castings, and processing this waste is the main reason people get into worm farming.

Please note you cannot run a worm bin on these food scraps alone. They do not provide any "sponge" structure to your worm bin necessary for them to breathe. Upon decomposition, they release a lot of water and your bin can get waterlogged quickly.

Besides that, these foods are high in nitrogen, which means if you add too much they can begin to hot compost - causing your bin to heat up more than what they worms can survive.

So try to make sure you are never adding so much food that it is causing your bin to become too wet or start to hot compost.

Here is an infographic from the squirm firm that gives a good outline of worm-edible foods.

You'll see a lot of attempts online to make "hard and fast" rules on how to feed your worms, but there's so many variables and it doesn't really work like that.

I'll try to just focus on the principles behind some of the rules so you can become self reliant.

Remember the red wigglers's hierarchy of needs;

Food is pretty much the least important thing.

So, you shouldn't ever be adding so much food that it jeopardizes the worm bin's balance of water and oxygen. (At least not without balancing it out with new bedding if/as needed.)

So basically, you're good to keep adding food if:
1. The bin isn't getting too wet
2. The bin isn't heating up
3. Other organisms such as pests or excess mold aren't taking advantage of excess available food.

Don't add new foods throughout the entire bin

Until you are familiar with the type of food you are adding and how the worms/bin will respond, don't add the food throughout the entirety of the bin. This allows the worms, if they don't like the material/conditions you've created, to just go to a different section of the bin (whether horizontally or vertically). If it has been added throughout the entire bin and something has gone wrong, their only option is to escape the bin as a whole. It is a good idea while you are still learning to always leave a portion (a third or so) of the bin free of any actively decomposing food as a safe space for the worms if you make a mistake elsewhere in the bin.

This also allows you to figure out if a food/type of organic matter will be okay for your red wigglers. You can ask your worms directly by adding some of the food in a small area in the bin. If they don't like it, worst case scenario is that they'll avoid that area and not touch the food. If they swarm it right away, they like it.

Maintaining Stable Conditions

You need to make sure your bin stays aerobic. Organic matter that will contribute to aerobic conditions in any quantity is considered bedding. Other organic matter would be considered food. The majority of your bin should be bedding, or finished worm castings/compost, at any given time.

Avoid certain types of foods

Generally you'll want to pass on feeding citrus, meat, dairy, spicy foods, salty, greasy, or oily foods. The red wigglers can and will eat these foods, but it may take a longer time for them to do so, and other undesirable organisms might take advantage of the available food in the mean time.

Bury Food

By covering food with a small amount of bedding (1/2 inch to 1 inch), red wigglers will be protected from any light coming into the bin that would scare them away from the food, the food won't dry out, and it will help hide the food from bugs such as fruit flies.

Fruit and Vegetable Skin

Although you don't need to do this, the worms will be able to eat a watermelon/grape/apple/any fruit with skin much faster if the skin has been punctured or the red wigglers are able to access the "flesh" inside.

Man, that sounds morbid without context. But, when I feed my worms zucchini, for example, I don't just put it in whole. You'll want to expose the inside somehow. Breaking or cutting it in half, cracking it open, or cutting a chunk out of it will greatly decrease the time it takes the worms to eat all of it.

Microbial Populations

The more microbes and more microbial diversity, the better. The microbial population should establish itself after the first few weeks (and is really only a concern as you first start), but you can always improve it/add to it by adding little inoculums of healthy (KEY WORD) soil/organic matter from healthy soils. I often go to parks, forested areas, or healthy garden soils. Just take a small amount of material (half a cup) and toss it in the worm bin. Be aware that you're adding anything else that might be in that handful - like any bugs. This usually isn't a problem because if you're not fostering an environment where bugs will thrive then they will go away, but you might introduce some roly-polys, or springtails, or millipedes that will live alongside your worms in small, normal amounts if your worm bin isn't totally unmanaged.

Avoiding Overfeeding

There are a few things that limit how much food to add at once. You don't want to create anaerobic conditions from excess water, you don't want to start thermophilic (hot) composting, and you don't want to add so much food that the worms can't eat quick enough so other organisms start flourishing on the extra available food. Whenever you make one of these mistakes you can always remove the food you added to help resolve it,  and if you are following the practice of only adding food in certain areas of the bin then its an easy fix. Read on to learn more about all of this.

Excess Moisture from Fruit and Vegetable Waste

As you are adding water-rich foods, like fruit/vegetable waste, they will release their water into your bin as they decompose. If too much water is released it can waterlog the bin and create anaerobic conditions. You will eventually need to add more dry bedding to counteract the excess moisture if the bin starts to get too wet.

Overfeeding and Pests

Ideally the red wigglers will be the main macro-organism eating your food. However, if some food waste hasn't been eaten by the worms and there's plenty of excess food that other organisms don't have to try to outcompete the worms to eat, you may start to see mites, mold, or other unsightly (but usually not inherently bad) organisms start to feed on the material. The key is to just provide enough for the worms - as long as you make sure its worm-edible, nothing is going to be able to outcompete the worms. Burying the food of course will help with this.

Overfeeding and Thermophilic Composting

If you add too much food that is too high in nitrogen the rapid microbial growth can cause the material to heat up - which can kill your red wigglers. Be aware of the general Carbon to Nitrogen ratio of the food you're adding. The higher the nitrogen content, the less of it can create heat. In situations where you are feeding them higher nitrogen material (such as coffee grounds with a 20:1), if you add it in small concentrations (only a small amount at a time/spread out more thinly) it will help prevent the heating up effect. Materials like fruit and vegetable waste are usually around 35-40:1 carbon to nitrogen and aren't so prone to heating up unless you have added a lot. If you are following the first step of not adding food throughout the entire bin the negative effects of this will be mitigated though as the worms will just avoid the hot areas - as long as it doesn't heat up the entire bin.

Surface Area

More surface area means more microorganisms can colonize the material and more room where the worms can start to eat. Again, this is not necessary, but will help a lot. You can increase surface area of the food you add by breaking/cutting it apart - most commonly and easily done with a blender.

The Unknown..

If these other things are provided for and the worms aren't eating it, its probably for a good reason. Red wigglers are very tiny but very advanced soil testers. It may be too acidic for them (citrus), too spicy (peppers), or have some chemical - natural or unnatural - that they don't like. Maybe there is some sort of herbicide, or salt, or something on the material. Its hard to say and I would have to leave the detective work up to you to figure out what it may be.