New Vermicomposter Questions

It seems my recent ‘Reader Questions’ posts have inspired some others to write in. (Keep em coming – I think these posts will really end up helping a lot of newcomers, and I certainly enjoy answering them).

Anyway, today I have some questions from Suzanne, who is new to vermicomposting.

Hi Bentley,
I am planning on setting up a worm bin in my basement soon. I live in Iowa, and it has been quite the winter. (Actually I don’t mind the winter as it is opportunity to snowshoes, ice skate, and watch lots of birds at the feeders…)

Here are some questions: (these are probably already dealt with in previous postings)
1) Can egg shells be put in the worm bin?
2) How about coffee grounds and tea leaves?
3) How about coffee filters and tea bags?
4) If the bin sits on the basement floor, will the radiant cold adversely effect the worms? It will not be any where near freezing, but could be chilly.
5) I also compost outdoors in the summer. Can worms be added to an outdoor bin or do they all migrate to the surrounding turf? I do have pretty active earthworms in the yard and gardens.

Thanks for being available!

Hi Suzanne!
Those are all good questions – especially useful for anyone just getting started with vermicomposting. I’m simply going to respond to each in the same order you asked them.

1) Egg shells can definitely be put in your worm bin – in fact I strongly encourage people to do so if they eat eggs. They add valuable calcium, some grit for the worms gizzards (used to grind up food), and can act as a pH buffer as well (preventing excessively acidic conditions from developing). Calcium apparently plays an important role in the worm reproduction cycle (its exact function escapes me at the moment), so adding shells can actually help to boost reproduction in your bin.

I would recommend letting your shells dry out then grinding them as finely as possible – this way the calcium will be much more readily accessible (whole egg shells will take much longer to break down). I typically put empty shells back in an old egg carton, continuing to stack them inside each other until the carton won’t hold any more. When I have a number of these cartons of shells I will then empty them into a clean, dry bucket then simply crush/grind them (the bottom of a jar or something similar should work just fine).

2) Coffee grounds and tea leaves are excellent additions to a worm bin and will be readily broken down into worm castings provided they are kept nice and moist (I’ve found that coffee ground in particular can dry out quite easily). I wouldn’t recommend adding too much of either material unless you plan to balance them out with something else (lots of bedding, ground up egg shells etc) – you may end up with a pretty acidic bin. I tried collecting large quantities of coffee grounds from a coffee shop and feeding them to the worms, but they were not particularly impressed. If I did this again I would use a much larger system and would make sure to lessen the amount added at any one time, or would at least mix it with other materials (eg fall leaves) before adding it to the bin.

3) Coffee filters and tea bags are very biodegradeable so you can certainly add these. I simply grab the filter full of coffee grounds out of our coffee maker and add it to whatever waste-holding container I have on the go at the moment (I generally store waste materials in a separate container or bag before adding to worm bin). Same with tea bags – we don’t drink all that much tea to be totally honest, but whenever we do use tea bags I am always eager to add them to my waste stash.

4) Assuming you are using red worms (Eisenia fetida) or european nightcrawlers (Eisenia hortensis), they should handle cooler temperatures just fine. The composting process in general may slow down considerably however if temperatures in your bin drop down below 10 C (50 F), so you may not be able to produce compost as fast as you like (or deal with as much food waste). The ideal composting temp range for red worms is 20-30 C (68-86 F), but apparently the ideal temp range for reproduction is somewhat lower (in the range of 15-20 C).

5) Composting worms are an excellent addition to a backyard composter, and assuming you maintain conditions that are to their liking (not very difficult) they will be more than happy to stay put. You will need to make sure the contents of your composter stay very moist (during the summer months many compost bins tend to dry out quite readily), relatively cool (if adding worms you may want to locate your composter in a shady area, especially if it’s one of those solid black plastic ones), and of course there also needs to be a decent amount of waste materials for them to feed on. I have a thriving outdoor worm bin, and also added some worms to another backyard compost bin with great success (it is now full of red worms as well). I think one of the main stumbling blocks for people is maintaining moisture levels. If conditions become dry the worms will migrate or die. They won’t however move down into the soil in large numbers – they are adapted for live in compost heaps and manure piles.

Thanks for the questions, Suzanne – hope I’ve helped!


[tags]worm bin, worm bins, red worms, composting worms, red wigglers, composter, composting, vermicomposting, worm composting, compost bin, food waste[/tags]

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