Building a Worm Farm

SUBHEAD: Instructions on building and maintaining a worm farm in your home. 
By Eric on 9 May 2009 for -  

Image above: A thriving worm farm in a plastic tub. From original article.

[Editor's note: The links between Part 1 & 2 of the original article are broken. All four parts are reconstructed here. For original Part 2 try]

So you want to be a worm farmer! What’s that, no…you don’t? Oh come on, what about all the free fertilizer and sparkling worm personalities? Kinda seriously, worms make for quiet, low maintenance and symbiotic pets.

Ok, well ‘pets’ may be stretching it, but vermi-composting (composting using worms) is a great way to reduce the amount of food waste you throw away and in return they will give you some fantastic, nutrient rich compost (castings). Did you know that food waste makes up about 12 percent of the total waste stream in the US? Now we can all take this simple step to reduce our environmental impact and our vegetables and other plants will love us for it. Plus…it’s fun!

When it comes to giving your worms a home, you have lots of options. There are all kinds of pre-fabricated bins out there and some municipalities will either give you a bin or subsidize one for you. I personally prefer to make my own bin because it’s easy and cheap to do. One other cool thing about keeping a worm bin…it doesn’t matter if you live in an apartment or a castle, there is a bin size sure to fit whatever space you have available.

Ok, I know what you’re saying. “I don’t want some stinky garbage can full of worms in my house…” and I don’t blame you! Believe it or not, your worm bin should not smell bad at all. In fact if it does smell bad, there is something wrong with it (we’ll talk about this later). The bin does have a pleasant “earthy” aroma similar to what you smell in a forest. It’s very tolerable and unobtrusive.

To recap: starting a worm bin will reduce food waste, create great fertilizer and make you the life of the party. There are no downsides to it!

Here’s a materials list of items you will need.
  • 2 “Rubbermaid” type containers. 18 gallons is about the perfect size. Larger or smaller work well also.
  • A bunch of newspapers
  • 2 — 2×4, cut to fit into one of the containers
  • 1 pound of worms, obviously, (red wigglers are the best for this) do a quick search on the Internet for someone that sells them near you. They run about $20-$25 for the pound and that’s all you will ever need to buy.
  • About 1 pound of food scraps
  • 1 drill
  • 1 bucket of water

Step 1- Drill some drainage holes through one of the bins (20 should be good). Try to drill the holes about the same size as the larger worms. This will allow excess water to drain down into the bottom (drainage) bin as well as create air holes for air to get into the bin.


Step 2- Cut your 2×4 to fit inside of the lower bin. Now put the first bin (the one with the holes) inside of this bin creating a “nested” worm bin. This bin is a drainage bin for catching any excess liquid from the main bin. If there is liquid in this bin, just pour it on your plants…it’s called “worm tea” and makes for excellent fertilizer. Don’t worry about over fertilizing your plants with this either. Worm castings are very gentle on plant roots.

wood supports

Step 3- Line the bottom of your bin with whole newspapers, paper bags, cardboard or any other natural material such as burlap, hemp, etc to create a temporary barrier to keep the worms from going through the drainage holes. I say temporary because eventually all the bedding and linings will be eaten by the worms.

lined bin

Step 4- Shred up a bunch on newspaper about an inch or so wide. Dunk it I the bucket of water, ring it out and throw it in the bin. Fluff up the newspaper. This is the bedding for the worms. You’ll want about 4-6 inches of bedding in the bin.

wet newspaper

Step 5- Now place your worms on top of the bedding.

worms on top of newspaper

Step 6- Now place your food scraps on top of the worms.

food scraps

Step 7- Shred some newspaper again, but this time don’t wet it. This is the covering for the bin. Shred up enough to fill the bin to the top.

shredded newspaper
Flash forward 4-5 months….
Step 8- This compost is almost ready. It’s time to get the worms out of it and let the remaining worms “finish” off the job and eat whatever is left in the bin.

Step 9- To coax your worms out of the castings, push all the contents of your bin over to one side. On the other side we’ll lay down some fresh bedding. Follow steps 3-6 above for one side. In about a month or so, all your worms will finish off whatever food scraps are left in the castings and move over to the other side where the fresh bedding and food is. After that, you can remove the castings and use them to fertilize your plants or make worm “tea” for liquid fertilizer.


And it’s as simple as that. Don’t worry about not knowing everything at first, or making mistakes. It’s really simple to do and if you stick with it through one cycle, you’ll be a master! You’re now on your way to the wonderful world of vermi-composting. Congratulations!

Some Helpful Tips:
  1. Remember, go easy on the food at first. It’s very easy to overfeed the worms and although it won’t cause them any harm, the bin my start to smell or attract fruit flies. Check on the worms every 4-5 days to make sure they are doing ok and the food is being eaten (start adding more food). Don’t be afraid to continue to throw your scraps away for awhile, or you can freeze them in a container and thaw them out for later. In time your bin will be able to eat more as the population gets larger.
  2. When the “covering layer” newspaper gets damp, just turn the damp paper up to the top of the bin and the dry paper down to bottom of the bin. This will allow it to dry out.
  3. If the bedding and covering layer still seems too wet, you can also open the lid or take it off for awhile to allow it to dry out. I actually rarely cover my bins completely in the garage. Sometimes the opposite happens and my bin will be too dry. To combat this, I’ll just put the cover on tightly and wait a couple of days. The moisture will build back up inside.
  4. As the bedding gets eaten, I like to gently “turn” the bin contents over to aerate it.
  5. To feed the worms, simply lift up the covering layer and place the scraps on top. Re-cover with the layer of newspapers. Alternatively, I prefer to dig down a bit into the bedding and place the scrape into a “hole” I create. This helps to get the food to the worms a bit faster.
  6. You should rarely, if ever, have to add water to moisten the bin. But if the bin is a bit dry, feel free to throw some in. The perfect consistency should be thoroughly damp, not dry or soaking.
  7. Pickup some rubber dishwashing gloves to make dealing with the worms a cleaner process.
Here are the answers to some FAQs.
Q: What do I feed my worms? A: Almost any whole, uncooked, food waste. Here are some examples:
  • Apple peels and cores
  • Carrot peels
  • Celery
  • Egg shells
  • Banana peels
  • Lettuce stumps
  • Pepper stems
  • Herbs
  • Bread
  • Tea bags
  • Coffee grounds
  • I think you get it
Q: Ok, so what can I NOT feed my worms? A: This is actually a bit easier to answer. Worms can eat a ton of stuff, but there are a few things that you should not feed them, either because they take a long time to break down or are too acidic or harmful to the worms. These items include:
  • Citrus peels or citrus fruit
  • Meats, fish, tofu, beans or other proteins
  • Cooked or prepared foods
  • Dairy
  • Onions
  • Fruit rinds (watermelon, cantelope, etc)
  • Anything with cooking oils on it, like salad dressings
  • That’s about it!
Q: What temperature do my worms like to live? A: About the same temperature you and I like to live in. Avoid placing their bin in direct sunlight or cold temperatures. I keep my bin in my garage, but other people I know put their bins under their kitchen sink or on their covered patio. Just remember if you’re uncomfortable with the temperature, they are also.

Q: How many worms do I need? A: Good question. About 1 lbs should get you started, that’s about 500 worms. Worms do three things: eat, poop and make more worms. In about two or three months, you’ll have double or triple that amount of worms in your bin! Oh and don’t worry, they won’t overpopulate the bin. After your first compost harvest, you can share some of your worms with friends and help them get their own bin started!

Q: How do I keep pest such as fruit flies and other insects from filling up the bin? A: Although fruit flies won’t hurt anything they can be annoying. Try to bury the food under the newspaper, this usually keeps the pests at bay. For ants and other crawling insects, a little petroleum jelly under the edge of the bin should stop them in their tracks. Although, I have really never seen any ants in my bin.

Q: When can I harvest the bin for all of the castings (worm poop)? A: Usually the bin is ready to be harvested in four of five months. See instructions on how to separate the worms from the castings (in the final part).

Q: I live in an apartment and don’t have any plants, what should I do with all the castings? A: Well you can give them to your friends or you can “guerilla” compost in planters where you live. The trees and other plants will love you for it.

Q: Can I add grass, leaves and other yard clippings to the bin? A: Very sparingly. The newspapers serve as the “browns” and the food serve as the “greens” in our little micro-world. Too much yard waste can overwhelm the worms and start to rot before they can eat it all. If you have a lot of yard waste, you may want to consider starting a traditional compost heap and use the worm castings to augment that compost. They go very nicely together and will create wonderful nutrients for your yard.

Q: What about vacation? Does someone need to watch the bin while I’m gone? A: The bin can sustain itself for about 3 weeks without needing any attention.

Q: The bin is a little smelly, what should I do? A: This is usually caused by over feeding or the lack of air. So, just reduce one and increase the other.

Q: Ok, this sounds like tons of hard work. A: Hard work is not…but it is some work. I would plan to devote 20 or so minutes a week to maintaining the bin. Most of this is spent feeding and “turning” the bin over to help aerate the compost. Like almost anything, the more experience you get the easier it becomes. I find it relaxing and enjoyable!

Q: I have more questions. A: Google, Yahoo, MSN is your friend. Do a quick search, there is a wealth of information out there. Also, feel free to contact me!

See also:
Ea O Ka Aina: Thinking like an Ecosystem 8/12/10
Ea O Ka Aina: Greetings from the Annelids 8/5/10
Ea O KA Aina: Kauai Bucket Gardening 4/14/10
Ea O Ka Aina: What Works - Food 3/29/10
Ea O Ka Aina: Kauai Organic Farm Tour 1/18/09
Ea O Ka Aina: Our first pullet egg 1/13/10 (how we built our chicken coop)


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