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Thursday, March 26, 2015

Critter of the Month: Eisenia fetida (Redworms) & DIY Vermicomposting

Several of the 300 "Hermans" - My pet redworms (E. fetida).
 This "Critter of the Month" post is dedicated to my gardener friends on Twitter, who recently inspired me to start my own vermicomposting (indoor worm composting) system.  Thanks to those "tweeters", I have  adopted 300 red-and-slimy new pets.  I have named them "Herman #1-300." (If you choose a worm at random from the bin, he shall be referred to as "Herman X." If you pick up 2, the second one would be called "Herman X+1" and so on...)

What are Redworms/ Red Wrigglers/E. fetida? 

Upon researching vermicomposting, I discovered that the worm most suitable to this task is Eisenia fetida, also known as the redworm or red wrigglers. So, I purchased the redworm "Hermans #1-300" from a company online, and set about making a home for them.

Redworms are a type of earthworm adapted to living in, and consuming decaying organic matter within the top 10 inches of the soil. They are nocturnal (active at night). This type of worm is native to Europe, but have been introduced  to every other continent in the world except for Antarctica.  In order to live, the worms require a temperature  minimum of 38 degrees Fahrenheit (3 degrees Celsius) and a maximum of 95 degrees Fahrenheit (35 degrees Celsius) .  They also require a moist medium to crawl through and good air circulation so that they can breathe. The worms' tolerance for heat depends on the level of soil moisture.  (More moisture allows for greater heat tolerance.)
Anatomy of a redworm. From
Redworms are (unsurprisingly) red in color.  They are basically a long digestive tube covered in soft muscular segments that allow for movement.  They are coated in mucous for both protection and to ease their movement through the earth.  They have groups of bristles called setae on each segment of their body that move in and out to assist the worm with movement and help to grip the surfaces that they crawl across. According to Wikipedia, "When roughly handled, an E. fetida exudes a pungent liquid, thus the specific name foetida meaning "foul-smelling."  This is presumably an antipredator adaptation."

Redworms are hermaphroditic (male and female at the same time).  They mate when two worms join clitella (reproductive organs) and exchange sperm.  Both worms then secrete yellowish cocoons that each contain eggs.  As the eggs mature, the cocoons turn brown, and eventually baby worms hatch from the eggs.  Red worm adults lay around 4 cocoons per week.  Each cocoon contains about 4 baby worms.   These eggs have an 83% hatching rate, so every worm produces about 11 young per week.  It can take roughly 35 days for the eggs to hatch, around 60 days for the worms to reach sexual maturity, and 120 days for each worm to reach full maturity. This is an extremely rapid reproduction rate! Soon I will have to change the "Hermans 1-300's" names to "Hermans X--> ∞"!

Each of these worms is voraciously hungry.  Redworms can consume up to half of their body weight in organic material each day.  This allows them to help to quickly break down waste matter in the environment. In addition, the worms castings (poop) are several times higher in nitrogen, phosphorus, potasium and magnesium (plant fertilizer/food) than normal soil.  On top of that, redworms leave tunnels in the soil as they search for food.  This causes the soil to drain better, reduces erosion, reduces the amount of water needed in the environment, prevents soil compaction, and allows organic materials to be better incorporated into the soil.  This makes them excellent natural rototillers and perfect for composting! According to, Worm compost is so excellent for plants that it can increase production by up to 40% and can improve nutrients in grain by 35%.  

How To Build A Worm Bin:
There are many worm bins available for sale, and many plans available for building your own available on the internet.  I built mine from a simple plan that I found on the Mother Earth News website.

Worm bin building supplies.

  • 2 opaque rubber bins size about 1 foot (0.3 meters) by 1 foot (0.3 meters) by 2 foot (0.6 meters).
  • 1 opaque bin lid
  • 1 clear plastic bin that is a bit longer and wider than the opaque bins
  • 4 PVC cylinders 
  • An old water bottle
  • A drill or other tool for punching holes
  • Shredded newspaper and/or dry leaves
  • 6-8 cups soil, dirt, or compost "grit"
  • Water (do NOT use water from a water softening system - the salt may kill the worms!)
  • Redworms (200-500 worms are ideal) 

Assembled & stacked bins.
Steps to Build:

1. Use the drill to punch around 30-40 holes in the bottom of each bin as well as the lid.

2. Use the drill to punch around 12 holes on each side of the bin.  Place the holes near the top of the bin, just below where the lid snaps down, and then around the center of the side of the bin below where the manufacturer left a ridge in the bin.

3.  Moisten the shredded newspaper and/or dry leaves.  This material should be damp like a wrung-out rag, not soaking.  When you squeeze it, only a few drops of water should fall from it, NOT streams of water.

4. Add the newspaper/leaf bedding to one bin along with the soil/dirt/compost grit.   This will become your first worm bin.
Worm bedding, plastic bottle air pipe and worms.

5. Add the worms to the bin.  You can order worms online at various sources (locate by doing a search for " buy redworms" on Google.) You can also collect them from your yard.  Be sure to choose the smaller, red-colored worms.  Do not pick the large brown colored ones.  The larger ones will not survive a worm bin as well as the red ones.

6. Cut the top and bottom out of the water bottle. Punch holes in the side.  Place this in the center of the worm bin. Leave the center of this tube empty.  This will allow for better air flow through the center of the bin. (You can also do this with paper towel tubes, but you will need to replace them periodically.)

7. Set the worm-filled bin on top of the 4 PVC cylinders within the clear plastic container and cover it with the lid.  The cylinders keep the holes in the bottom of the opaque bin from being blocked by the plastic from the clear bin.  The clear bin will catch any water that happens to leak from the opaque bin.

8. Reserve your 2nd opaque bin for when the worms reproduce enough to overtake the first bin.  Once the first bin is full, you can fill the 2nd bin with moistened newspaper bedding and add some worms from the first bin to the second bin. Then, you simply stack the 2nd bin on top of the first.  Now you have a worm tower!

Care And Placement of The Worm Bin: 
 The worm bin should be kept indoors where the temperature is worm friendly: between 50 and 75 degrees Fahrenheit (10-24 degrees Celsius) and where there is good air circulation.  A basement, insulated/heated garage, wide dark cabinet, or dark closet are perfect. Avoid leaving them outside where extremely hot or cold temperatures can kill the worms.  Remember, the worms in the bin cannot dig down into the earth to regulate their temperature like worms can in nature!

Try to secure the bin in an area out of reach of pets and small children to avoid spilling the bin and causing a mess.  Securing the lid with a bungee cord may also be advisable.

Try to keep the contents of the bin about as moist as wrung-out rag.  At first, you may have to add moisture with spritz or two of water.  As the worms begin to feed, the moisture from the food may accumulate in the bin.  That is why it is important to allow the bin to drain and to place it in an area with good air-flow.  If the worms appear to be trying to escape the bin, it may be because it is too wet.  If this happens, add some dry bedding.  If that is not enough to keep the bin at the right moisture level, consider cutting a large square through the lid of the bin and then duct-taping some screen material to the hole to allow for better air flow.   Keep the depth of the contents between 6-8 inches.  This will help to maintain the moisture level while providing the worms enough medium to crawl through.  If this doesn't seem like enough room, start a second bin, add the worms to your garden, add them to your outdoor compost pile, feed them to your chickens or go fishing with them!

Sometimes, when the bin matures, it attracts other insects.  These include mites, pot worms and black beetles.  These are harmless to the worms and will aid in the decomposition process. So, don't worry if you see them!

Feeding The Very-Hungry Worms: 

 When you first add worms to your bin, they may take a few days to "relax."  Remember, they have been shipped through the mail: the equivalent of an several-day earthquake for the worms! Some may even try to escape the bin at first.  To prevent this, leave the light on in the room where you have placed the bin.  The worms will try to avoid the light, and stay inside the bin to hide. Also, do not feed them for their first day. If they become hungry, they will eat the bedding.  It is more likely that they will not eat at all, because they need a chance to get over the nausea and trauma of being tossed about by the postal system.

In theory, worms can eat about half of their weight each day.  In reality, this varies quite a bit.  Worms like some food more than others so may devour one thing that you add quickly, and ignore another thing for days.  Another thing that affects their appetite is a new bin.  A new bin generally contains fewer worms, so they don't eat as much as a mature bin that is teaming with worms.  A new bin also contains fresh bedding which the worms may choose to munch on instead of the table scraps.  As the bedding breaks down, they will eat more and more of the table scraps that you provide.

Try to avoid over-feeding the worms. If too many food scraps accumulate in the bin, the bin may begin to stink.  It may also attract unwanted pests such as flies. Start by feeding the worms about a cup of scraps.  Leave these for the worms on top of the bedding so that you can monitor what the worms are eating easily.  It is best to chop the scraps up in order to assist the worms in grabbing them.  Once the scraps from the first feeding have vanished, add more.  Over time, you will notice that the scraps get eaten more and more quickly. When this happens try adding a bit more at a time.

Worms work together with bacteria and fungi to help decompose food.  They prefer rotten food to fresh, so it may take a couple of days before they consume the food that you add to the bin.  This is normal.  Worms will eat any kind of biodegradable material except for those containing and excess of oil, salt, or chemicals.  They prefer mushy food (e.g. oatmeal) to hard food (e.g.) parsnips.  They also cannot digest seeds.  So, please remember to remove any seeds from your table scraps before adding them to the bin. In addition, you should not add meat, dairy or bones to the worm bin. This will only begin to stink and will attract maggots. Finally, do not add acidic foods such as citrus or vinegar to the bin. This throws off the pH of the bin and the chemical lemonine found in citrus can harm the worms. Please think of your worms as toothless vegetarians and feed them accordingly.
Worms love to eat:
  • Coffee grounds 
  • Tea leaves
  • Crushed eggshells
  • Fruit of all sorts, except citrus
  • Lettuce
  • Oatmeal and other cooked grains
  • Squash
  • Corn Cobs
  • Melon rinds
  • Plain popcorn (no salt, no oil or butter)
  • Wet bread, pasta or other grain products
Worms will eat:
  • Chopped vegetable matter, fresh or cooked
  • Newspaper and uncoated cardboard
  • Most chopped garden scraps
  • Dry leaves
  • Coffee filters
Do NOT feed worms:
  • Inorganic material: plastic, rubber, metal, glass, or chemicals.
  • Citrus of any sort
  • Dairy (Traces are OK.)
  • Meat
  • Poultry
  • Fish
  • Bones
  • Seeds
  • Oil
  • Pet feces (this can cause human disease when the compost is used in the garden, and it stinks)
  • Processed food (potato chips, candy, Twinkies etc.)
  • Sugar (Traces are OK.)
  • Salt or salty foods (Traces are OK)
  • Vinegar
  • Garlic, onion or hot pepper trimmings
  • Trimmings from cabbage-family crops 
How to Use the Worm Compost:

Around 2 months after you start the bin, the contents should start to turn black.  When this happens, it is time to harvest the castings!  To do this: stop adding food for a few days and allow the worms to finish eating any remaining scraps. When you no longer see any scraps, put a big piece of your worms' favorite food on the far end of the bin to lure them in that direction.  The next day, scoop out
the compost at the end of the bin opposite where you put the treat.  Allow this mixture to dry in a bucket somewhere.  When it is dry, sift it for later use in your gardening endeavors.

You can use the compost for the following:
  • Add it to your potting soil
  • Top dress your potted plants
  • Top dress your garden bes
  • Prepare planting holes
  • Rejuvenate plant containers
  • Make compost tea as a liquid fertilizer
To make compost tea:  Place 1 pint of worm compost in a bucket. Add 1 gallon of warm water and a spoonful of molasses. Stir frequently over the next 48 hours. Dilute the resulting liquid at the ratio of 1 part tea to 4 parts water. Use it to water your potted plants, garden, or fruit trees.

 I hope that this article is helpful to those of you who are interested in starting a vermicompost bin, and that you found this creepy-crawly- critter-of-the-month to be as interesting as I did!

The 300 Hermans appreciate your interest!


Pleasant, Barbara et. al. The Complete Compost Gardening Guide. Storey Publishing. 2008. Pgs. 206-217.