Speaker: Dr. John Biernbaum, Michigan State University Dept. of Horticulture where they have a year-round student run organic farm and CSA.

Here are notes of things that I learned and took away:

    John’s done specific work on worm composting in unheated structures (more challenging than in heated facilities). This is particularly challenging in Michigan.

    Another focus — maximum production per acre

    His focus is on creating compost as a resource (not so much focus on the waste management end)

    There are 6000 species of worms and only 6 are used in composting — the main one being eisenia fetida (the red worm, red wiggler worm, manure worm)

    Worm biology – worms don’t have teeth so depend on other organisms in the soil to break things down. Also worms don’t have lungs so there needs to be moisture so they can absorb oxygen through their skin.

    With bigger beds, they’ve moved to pre-composting the worm’s food for efficiency, as opposed to burying food in the bins.

    Reproduction — worms are hermaphrodites but do mate, then they lay cocoons. They may start to mate at 60 – 90 days depending on conditions and can create 2-3 cocoons a week. Cocoons take 4-6 weeks to hatch. Worms can live 3-4 years in an ideal system. Rates of reproduction depend on conditions and limitations of the system.

    We were asked to raise our hands to indicate our experience by the number of years we’ve been worm composting and the number of square feet of surface area that we operate.

    Population density measurement — he started out managing horse manure composting and can see that cubic feet is a measure for some systems like windrows. Square foot of surface area is also common — 2-3 pounds per square foot would be considered high population.

    Moisture measurement – % moisture content (wet weight – dry weight)/wet weight. 70-90% is a target range, but not if there is too much food in the bin. If you aren’t weighing the bedding, do the squeeze test. If you squeeze a handful and it falls apart — it is below 40% — too low. Ok is if you squeeze it and it stays in a ball when you open your hand (60%) Ideal is to squeeze it and a couple drops of water come out.

    Oxygen – temperature is a factor, as temperature increases, oxygen solubility in water decreases. Also avoid closed containers.

    Food – Carbon, Nitrogen, Minerals. In a feeding systems they need to be balanced. There are lookup tables showing makeup of inputs and available minerals.

    If you have 100 pounds of worms and are giving 50 pounds of food — consider moisture content of the food to know how much you’re actually feeding.

    Feeding trial: Horse manure .5 of weight per day was lowest – 1 of weight per day was mid, plate scrapings were highest.

    Temperature. Range is between 40 degrees F to 85 degrees F. Optimum is around 77 degrees.

    pH: affects nutrient availability for worms and plants. Note: ammonia gas becomes toxic in a high pH system.

    Soluble salts: impacts moisture availability. They accumulate in a system over time and will stress the worms. Not a problem in a flow through system.

    Bulk density — impacts oxygen transfer — indicates if there is too much soil which results in migration.

    Conclusion — quantifying can take away guesswork in worm composting.

The reference text sold at the conference, Vermiculture Technology: Earthworms, Organic Wastes, and Environmental Management, is available on Amazon.com in hardcover and for Kindle.

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NCSU site of vermiculture conference attended by Red Wiggler SupplyJust getting an agenda and seat at the conference — it was a brisk but pretty walk to the hall. The introduction will be by Rhonda Sherman, from the Biological & Agricultural Engineering Department here at NC State University who organizes these conferences every year. This is the 14th year and participants are from 7 countries and all over the US. There are 130 people here.

First the participants were given an orientation — parking, facilities, location of recycling and compost bins — pretty important with this crowd. At lunch we’ll compost our paper plates, cups, and napkins of course. There will be a networking evening at the Brownstone Hotel. Conference materials will be posted online after the weekend. See the other posts in this blog for speaker notes.

Tomorrow Susan will be representing Red Wiggler Supply at the annual conference on the latest in vermiculture (worm composting) at North Carolina State University in Raleigh, North Carolina.

Description: “A conference about earthworm farming and commercial vermicomposting taught by industry experts. This conference is for beginners or seasoned earthworm farm operators.”

I’m very excited and will take notes during the presentations and post them throughout the day. The lineup of speakers is posted on their website under “Agenda”.

Question: I have an aquarium I’d like to use for a worm composting project in my classroom. Will this work and do you have any tips?

Great question. I’m not sure worm composting is the right project for an aquarium. I can see that you like the idea of being able to see the worms, as you would in an ant farm, however the reality is that worms don’t like light and won’t hang out in plain view. Also, they may try to escape the habitat at night. Drainage also might be an issue.

If you’d like to try it anyhow, you could start with lots of premoistened shredded cardboard in the aquarium — fill it most of the way full. Then add some established compost with the red wiggler worms and some kitchen scraps on top of the bedding. Then lay a thick damp section of newspaper or two on top folded to the size of the top of the aquarium. You’d lift this thick pad of paper up to add food to the tank.

Moisten the system only if the bedding is drying out. Most successful worm bins have drainage holes at the bottom so water doesn’t stagnate, so you’ll want to watch to make sure water’s not collecting at the bottom.

Let us know how it works out! Has anyone else tried an aquarium as a worm composting habitat?

Update: Week two and so far so good. The teacher taped black paper on the sides of the aquarium that the students can lift to see the worms.

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Have a basic one layer box for a worm bin? There is an easy way to collect the compost — it just takes a bit of patience! You don’t even have to handle the worms (unless you want to of course!)

Red wiggler worms deposit most of the castings on the bottom, so if you dig down and the bedding has been turned into thick dark castings, it is probably time to harvest it. Here are the steps:

  1. With a small shovel, push the heavy old compost, worms and all, to one half of the bin.
  2. Add moistened fresh bedding — shredded newspaper or cardboard — to the bottom of the other half of the bin.
  3. Push any recently added, uncomposted food scraps, worms and all, over onto the fresh bedding.
  4. Add some fresh food scraps to the new bedding.
  5. Top off the new side with a layer of moistened newspaper or other bedding.
  6. Wait a month. the red wigglers will migrate from the old compost to the new bedding.
  7. Collect the finished worm-free compost.
  8. Fill the empty side with fresh bedding and add food scraps as needed.


People interested in worm composting — from beginners to industry professionals — are invited to an annual conference at North Carolina State University Oct. 26-27. Speakers from around the world will be sharing their knowledge on vermicomposting practices.  Information is here: http://www.bae.ncsu.edu/workshops/worm_conference/. Stay tuned — we’ll post information we gather on the latest practices as they apply to home composting with red wigglers after the conference.

If you’re into gardening, canning or preserving, you may have lots of overripe fruits, peels and cores to add to your worm compost. Keep in mind that adding too much of one item can upset the balance of your worm bin.

When adding acidic fruits such as apple, citrus, pineapple and tomato, put them in one corner of the bin so that worms can eat them when they’re ready!

Shredded cardboard and paper in Worm Factory tray

Shredded cardboard and paper in a Worm Factory tray

Cardboard is a great bedding and addition to your compost bin. It adds a carbon-rich “brown” component, and worms love to eat it. The texture of the cardboard provides a rich microbial environment for the worms, as well as properties that hold moisture and promote airflow in the bedding. The worms may even get nutrition from the glues in corregated cardboard.

Cardboard can be added in sheets, but if it is torn up or shredded they’ll break it down faster. Added to the top of a tray or bin, it can keep in moisture, prevent odors from developing, and keep the fruit flies away.

By observing your bin, you’ll see which foods they prefer over time. Here are some favorites:

  • Squash and pumpkin
  • Melon rinds and pulp
  • Avocado skins
  • Banana Peels
  • Mango

Foods they don’t like so much are:

  • raw potato peels
  • onions and garlic
  • acidic fruits like pineapples and citrus
  • hot chilies
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If you have a large outdoor worm compost bin, you may want to add grass clippings to the mix. One problem is that finely cut fresh grass often heats up to a temperature that is too hot for the worms! If you want to compost grass clippings, add them to one side of your bin so that worms can move away until they cool off. Another option is to precompost them in a separate pile before feeding them to the worms.

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You can mix the worm castings from your bin with water to make a liquid fertilizer. This compost tea is an excellent fertilizer for both outdoor and indoor plants. It can also be sprayed on foliage to ward off insects and disease.

One common misconception is that liquid that drains from your compost bin is “tea”. This drained liquid is actually called “leachate” and should be used as a fertilizer with caution. If it comes from a mature worm bin, it is probably a fine fertilizer, but if your bin still has some uncomposted material or anaerobic areas, the leachate could contain unstable compounds that could harm your plants. If in doubt, use leachate on less sensitive areas of your garden.

Leaving your worm bin while you’re on vacation is fine — just prepare a comfortable environment for the worms:

  • Move bin to a cool, dry place, protected from sun and rain.
  • Make sure your bin has some airholes or cracks for ventilation.
  • Harvest excess castings from the bin and replace it with fresh bedding
  • Add food scraps to two corners of the bin and cover with fresh bedding.
  • Moisten the bedding, and help the bin retain moisture by adding a mat of wet newspaper on top.
  • Make sure there is no standing water in the bin and (empty the drainage reservoir if necessary).

The worms will break down the new food scraps and fresh bedding while you’re away. They will turn them into well processed castings if you leave them for an extended period of time. After they consume the bedding and food, they will not multiply as quickly or grow as fast. If left longer than two months, you should have someone add fresh food, bedding and moisture to the bin.