Feeding Compost Worms: What, When, & How {Guest Post}

Today I’m thrilled to have my blogging buddy Holly from Your Gardening Friend guest posting today! She has been doing a fabulous compost worms series on her blog, and I am excited to have the 4th installment here on The Prairie Homestead.

It’s time for another compost worm post. If you missed the previous posts, you can catch up on the series with the below links.

1. 14 Reasons to Have Compost Worms

2. DIY Compost Worm Bin

3. How to Acquire Compost Worms

WHAT to Feed Compost Worms

Compost worms’ diet is similar to a vegan diet. Basically, stick to things that grow out of the ground. It’s the best comparison I can think of, but there are a few important exceptions to the worms’ diet:

  1. No processed food (there may be a few acceptable ones, but, in general, no processed food);
  2. No onions (I’ve read conflicting info on this one), but green onions are okay;
  3. No oils (olive oil, sesame oil, butter [but vegans don’t eat that anyway], etc.);
  4. Citrus and other highly acidic food in only small quantities; and
  5. All the food should, ideally, be spoiled.

Those are the biggies.

There are also some “extras” that compost worms eat, but vegans don’t eat:

  1. Coffee grounds,
  2. Worm castings (worm pooh), and
  3. Paper.

After the paper is broken down considerably, through moisture and LOTS of time, it becomes edible to worms.

HOW to Feed Compost Worms

Break the food into small pieces. Think of feeding compost worms like preparing food for a 9-month old baby. While you can put large pieces of food into the worm bin, it’s best to give them small pieces. Breaking, cutting, or tearing the food into smaller pieces provides more surface area for bacteria to break down the food. (Worms LOVE bacteria.)

I usually put the food into a plastic bag, and smoosh the food while it’s in the bag. Or, if I have something like a cucumber that has started to spoil, I slice the cucumber along the length, and, with a knife, I chop away at the “meat,” to loosen it up.

Bury the food under their bedding. This is very important. Compost worms don’t spend a lot of time on top of their bedding, although they do peak out often. However, the most important reason to bury the food is to keep the bin (and the house) free of odors. A smelly bin will also attract bugs. When the food is buried, a worm bin is odor-free. Their pooh, also, has no odor (regardless of whether or not it’s buried).

To bury the food, I like to use a cheap latex/non-latex-like glove (only needed on one hand) to keep the “soil,” pooh, and food from getting on my hands and under my fingernails. I reuse the same glove NUMEROUS times.

WHEN to Feed Compost Worms

How often do you think compost worms need to be fed? Are you thinking twice a day … once a day? How about once or twice a week!

I’ve read compost worms have a voracious appetite, I even mentioned that in 14 Reasons to Have Compost Worms, but I’ve not seen it first-hand. I’m finding that to be a good thing, though. Supposedly, the rule of thumb is that compost worms will eat half their weight in food every day. Meaning, if you have a pound of worms, they will eat up to half a pound of food every day, or 3.5 pounds every week. Fortunately, my worms are a little more concerned about their figure.

I recommend starting with a small amount of food, in proportion to the worms you have. Check the food stash in their bedding after a few days. It’s actually better to give a little less than too much. Don’t worry about starving them – within reason, of course. From my earlier research, I learned that putting too much food in the worm bin is one of the major causes of compost worms’ early demise. Remember, they’ll eat their bedding, the composted “soil,” coffee grounds, and their pooh.

Here are a couple tips for managing your food waste:

  1. Don’t have enough food waste? Ask a local restaurant or school/work cafeteria if they’ll set aside the fruits, veggies, and bread they typically throw out. I did that once when I thought I would not have enough food. Don’t forget about Starbucks. They give away bags of used coffee grounds for garden use.
  2. Have too much food waste? Toss it in a freezer bag, and freeze it until you need more. That’s what I do with some of ours.

Well, that pretty much sums up what you need to know about feeding compost worms.

Does any of this info surprise you? Or, do you also have an established compost worm farm?

Holly is a wife to her loving husband, John, and a “mother” of three canine “kids”. She loves sharing her faith; spending as much time as possible gardening and landscaping; sharing recipes you can make from your garden; and enjoying all the garden critters and wildlife at her country home, nestled in the woods. She blogs at Your Gardening Friend.

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  1. says

    Great post and photos! With my daughter’s help I have been “dabbling” in worm composting. Since the worms are silent I always forget they’re there but whenever I check they are busy as can be.

  2. Bee says

    I placed wet cardboard on top of shredded paper, bit of sand. Put in the worms – about six – under the wet cardboard I put the food – apple cores, carrots, banana peel, etc. Is there supposed to be mold growing? I can smell a faint moldy odor when I lift the cardboard to feed the worms. They have about doubled in size and I think there are several more than the orginal six. Concerned about the mold –

  3. says

    The mold is perfectly fine. Actually, mold is a worm’s friend. 😉 Personally, I don’t like to put real moldy food in the worm bin. However, as long as you’re not giving them more food than they can consume within a few days to a week, it’s probably fine.

    It might be better to bury the food under the wet shredded paper though. I’m not sure what your worm bin is like, so you might check out DIY Compost Worm Bin (http://yourgardeningfriend.com/2012/06/04/diy-compost-worm-bin/). You want to be sure to give them a deep bedding, around 6 inches of wet shredded paper, shredded cardboard, etc. The food should be buried under/within the bedding.

    Sounds like your worms are enjoying the food, though, if they’ve doubled in size. Keep up the great job! :)

  4. says

    Great post and pics about food types for worm bins! I have found my worms like cardboard a lot more than regular paper or even newspaper. I tear it up into small pieces, put it in a bucket of rainwater, and then place on top of the bin- it keeps it moist and the worms eat it faster than the newspaper I used to use.

  5. says

    Thanks, Jill!

    I welcome the tips, too! I use some cardboard, but I guess I should use a lot more. I use mostly my junk mail, but I’ll have to increase my cardboard ratio with my next bin.

  6. Kim says

    If I have more than a small handful of trimmings, will often do a quick chop/blend in the Magic Bullet to make them baby food. They seem to like it. And they go crazy for mango pits! I got my first bin from a guy on Craigslist, established DIY bin with a pound of worms for $20. He used a small pumpkin for the food. I used tomato this and that also for food. The next year when I used my castings in the houseplants, I ended up with squash and tomato plants sprouting up out of EVERYTHING!!!!! It was insane.

  7. Tammy Maynard says

    If at all possible try not to leave your worm castings in the bin long enough for the worms to start eating them again. The more times the castings go through the gut of the worm the more nutrient you lose in the castings that could be going to nourish your lawn, garden, plants, etc…. Worms will actually break newspaper down very quickly. We use newspaper, brown grass and peat moss as our bedding material and have been keeping worms for over 10 years in that mix. Love vermi-composting!!!

    • rou1 says

      Egg shells are mostly Calcium.I like to put my shells into a blender and turn them to powder before adding it to my bin.As the worms consume the calcium and food, each individual worm cast comes out with a calcium coating. Like an M&M’s candy coating.

  8. Sandi J says

    I’ve had worms for about 5 yrs, I also put a handful or two of dirt and leaves from the yard into the bin plus the newspaper and cardboard. Egg shells are great in the bins also, just crush them very fine,and they love coffee grounds and tea bags too.

  9. Ginelle says

    I have a few questions – If you bury the food under the surface how do you know when it is time to feed them again? I get lots of coffee grinds from a market near my house. Is it possible to feed them too much of the coffee grinds? Could they get too much caffeine? And should they have a variety in their diet? Or does that matter at all to worms? All input welcome to this new worm farmer. Thanks.

    • rou1 says

      Coffee grounds may be a bit on the acidic side so don’t add too much at one time. And the larger the variety of foods you feed your worms the better.One plant may have more of one type of mineral than another.

  10. Carole P. says

    On the DO NOT list should be seeds, such as seeds from blooming herbs and ripe tomatoes. Worms can’t digest seeds, so they survive the composting process and germinate like weeds when you use the castings. I didn’t know that when I started my first two bins, so I put in a lot of anise hyssop trimmings with the spent flower and I put in chopped up ripe tomatoes about to go bad occasionally. I had anise hyssop growing everywhere, plus volunteer tomato seedlings everywhere I didn’t want them.

  11. Jayne says

    This is all new territory for me, so I have probably some obvious newbie questions:

    Does a worm bin ‘have to be’ in the house?

    How do you remove the ‘castings’….which I think from here is the worm processed compost, yes/no?

    How many worms does one start with? Do they propagate or simply grow in size?

    Most likely I will be back with more questions later. 😉

  12. Linda Harrison says

    My worms love to find food in different places. But best of all they adore finding the food under cardboard.

  13. cjwntaw says

    Greetings to all. I have just started my new venture on worm farming. I have made a stacked compost bin out of three dark blue storage bins from Lowe’s. Worms do not like light too much.
    On the bottom one I did nothing to it. The top and middle one I drilled 1/4″ holes two inches apart for castings and holes 4″ from the top for ventilation. I know that worms are hermaphrodites in that they have both male and female parts which aid in reproduction. I plan to sell the worm castings, but I do not know the type of bags to put the castings in. Can anyone help?