Worm Symposium - summary of discussion

[Compost Santa Cruz County]

Advanced Worm Composting Symposium

November 27, 2022 at the Live Oak Grange

 

Summary of the Discussion: questions, answers, and best practices offered by the 19 participants:

 

– Set up and starting a new tray.  Should we use the coir that comes with it and is it sufficient as bedding?  Jeffrey mentioned that Marla does not use the coir as it takes too long to break down.  Others commented that they use newspaper, paper to-go containers, paper towel rolls, shredded paper, and shredded corrugated cardboard.  Someone said they use bedding as a topper to the food they feed the worms – their version of a carbon cap.

 

– How many trays are you using?  Most people were using 3 trays, one was using 4.  The people with 2 trays wanted a third.

 

– Bin placement – heat, cold, rain.  Someone had it in his kitchen and Jeffrey in his office.  Most people had theirs outside in a covered area to keep rain off.  Someone had hers in a fenced area to keep the dogs and kids away.  Michele keeps hers in her shed.

 

– Worms' most and least favorite foods.  FAVORITE: lettuce, mangoes, watermelon, pumpkin, bananas, bell peppers, carrots, potatoes, coffee grounds, sawdust, sweet potatoes.  LEAST FAVORITE: mangoes, oranges, celery, kale, eggshells, Brussels sprouts, cabbage, onions, citrus, garlic.  Special emphasis placed on the benefits of making the food small.

 

– Feeding quantity and frequency.  I did not hear anyone mention quantity, but most people fed weekly, some daily, and others a couple of times a week.  It sounded like the person who fed daily, just took his scraps out that he had used that day in his home, so likely smaller quantities more often.  Talked about worms’ gizzards needing some kind of grit.  Many use pulverized dried eggshells.  One person uses clay.  A little dirt also works.

 

– Bedding materials and quantity used.  Shredded newspaper, brown paper bags, shredded corrugated cardboard boxes, shredded paper, sawdust, toilet paper and paper towel rolls, paper egg cartons, dried grass and weeds, leaves and blossoms.

 

– Carbon Cap materials.  Wool Can-o-Worms cap from manufacturing company, cardboard, newspaper, paper bags, cotton t-shirt, coffee filters.

 

– Who's living in the bin?  Roly Polies, worms, cocoons, mites, small white worms, springtails, soldier fly larvae, beetles, fruit flies, mold, microscopic organisms.

 

– Harvesting castings – when and how?  Marla displayed her finished bin with worm castings and suggested the lack of grit as you rub castings between your finger tips.  Not being able to identify organic matter, but having a fine, pudding-like product that sticks together when squeezed.  Best practice for harvesting: when the top tray is full, move the bottom tray with mature castings to the top of the stack (each bin ends up a level below) on a sunny day and leave the lid off.  The bright daylight causes the worms to dive down, and after 20–30 minutes, you can scrape off the top ½ to 1 inch of castings, then wait and repeat, continuing that process until the worms have all moved down to the next lower tray and you have harvested all your castings (hopefully saving cocoons when possible).  You end up with a nearly empty tray on top where you need it.

 

– Use of castings.  Discussed benefits of making worm tea with castings with some believing aerating the mixture was helpful.  Some mix it with their soil during planting.  Discussed the problem of castings hardening when left to dry on the top of the soil.  People seemed to be well acquainted with the fertilizing benefits of using the castings (as tea) on all their fruits, herbs, plants and trees.

 

– Leachate vs. Worm Tea.  Robust discussion of difference between the two, with leachate being the excess moisture from the food, rain, and other liquid added to the bin that is just runoff, containing whatever pathogens and pesticides that the food contained.  Worm tea, on the other hand, is a liquid made combining worm castings and water (and possibly aerated).  Because the castings, or worm poop, has gone through the gut of the worm, they are 99% free of all pathogens and pesticides, making the tea a pure and safe fertilizer for all edibles in the garden.  Someone asked if leachate, used undiluted, would burn the roots of a plant.  Marla said that leachate is pH neutral and will thus not burn a plant.

 

– Moisture level.  How wet is too wet?  Some people water their bins, but others say they get a lot of leachate and may be adding too much moisture.  Discussed need for trays to be moist, but not anaerobic.  Others don’t water bin at all.  Liquid level in foods should be taken into account as well as the method of chopping food (Cuisinart slushy is wetter).

 

– How long until the castings are ready?  It may take 4–6 months for castings to mature into a dark sticky pudding.  Susan mentioned she does not wait for worm castings, but instead harvest her vermicompost as fertilizer, which takes her about 2 months.

Notes by Michele Elia