Preparing food for vermicomposting

Instructions that come with commercial worm bins vary in the way food is given to the worms. They will all tell you to chop your scraps up small to allow a maximum surface area for microbial action, but do you add them straight from your plate or chopping board, or do you pre-rot first in a separate container? And what about 'fancy' treatments like freezing or microwaving?


Well, first of all, your worm bin can take food scraps fresh, as soon as you produce them. Cover them with some bedding and you should never get any smells. But worms can't start feeding on those scraps until they start to break down. Usually they have other food to be getting along with so if you have a limited space, adding your scraps straight away in the worm bin shouldn't be a problem as long as you're careful not to overfeed. (See: Overfeeding a worm bin) In general a good rule is not to feed new food until the worms have moved into the last feed.
So why pre-rot, or pre-compost food? Well, apart from the convenience of keeping a scrap jar under the sink if your wormery is at the end of the garden, the worms can get to work alot faster, if the food is already started going soft and mushy. And you can have some control of the rotting or composting process. You can mix the scraps each time you make a new additition, to give aeration. You can pour off any excess liquid that pools at the bottom of your container and might promote anaerobic conditions. You can add some more carbon-rich material (paper/ cardboard) to absorb liquid and get the compost really cooking (you don't want that much heat happening in your worm bin in summer). And you don't disturb your worms as often by opening up the lid and making changes to their environment.
So what about 'fancy' treatments? Some people freeze their scraps then de-frost them before giving them to the worms. Apart from being a handy way of storing a large amount of food until you have more worms or a shortage of food, freezing actually helps break down food. As ice crystals form, they disrupt cell membranes- hence defrosted raw vegetables are mushier than fresh. This mushiness is good news for the microbes! Hard to break down foods like potatoes, raw carrots, brocoli can benefit fom this treatment. During the defrosting process some people also choose to pour off liquid- this results in loss of nutrients (unless you pour the liquid onto your plants) but can be a way of managing moisture in a bin- especially a closed one.
Freezing for more than three days will also kill many insect eggs- particularly fruit flies. Contrary to common belief- most fruit fly invasions (of your house or your worm bin) come not from your garden, but from your fruit bowl, where the tiny eggs hitch a ride home with you from the supermarket.
So what about microwaving or other heat treatments (for example putting food in the oven after you switch it off to catch the remaining heat)? Again, heat can help break down foods and kill fruitfly eggs. Just remember to cool things down before throwing in on top of the worms!

Personally I have two 'scrap' bins. I fill one, then when it's full give it a good mix, add some paper or cardboard if I need to, some vermicompost to add good microorganisms, and some hot water to get things really going. Then I fill the second bin, give the first the odd mix while the second is filling, and only empty the scraps to the wormbin when I need the container. Usually the mix is still warm, sometimes a bit smelly, but the worms dive in and seem to love it!

Pictures: Dried vermicompost, mixed waste, fresh container lined with paper

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Batch composting

Today I started a couple of batch vermicompost bins with some excess waste I had building up and because I thought that the worm populations in some other bins were getting high, and overcrowding doesn't encourage breeding.



So far on this site I have described the process of continuous vermicomposting- a worm bin is set up and waste material for composting is added gradually, as it becomes available. Continous vermicomposting can be either closed where you keep adding material until the bin fills, or flow-through.
With a closed system, when it is full, the compost, worms and undigested material are separated in a process known as 'harvesting', and the process is then re-started.
In flow-though system, harvesting and feeding are continuous. Feedstuff is added at one end, and compost removed at the other.

Batch composting, on the other hand, is when all the materials, bedding and waste are placed in a container with worms and left until the material is all converted to compost. Nothing new is added during this process except water, if needed. The container can be as small as a plastic box or as large as you need. In India for example, vast pits are dug in the ground, worms in some sort of safe bedding are placed at the bottom and pre-composted agricultural waste is added on top. The pit is covered to protect from sun and to reduce evaporation, and the only care it gets until harvesting is a check on moisture levels.

My batch bins were started with some aged horse manure followed by worm-rich partially-decomposed waste from three other bins (including the overfed can-o-worms) that I felt looked as if they were getting crowded), and some 'new' kitchen waste that had started decomposing nicely (it was warm to the touch). I added some shredded cardboard to the new kitchen waste to balance carbon nitrogen rations and to improve aeration. The three additions are kept separate- the manure is a safe layer for the worms to retreat to if the decomposition process gets nasty.
I won't be adding anything more to these bins, just checking on them about once a week to make sure they're not drying out or the food isn't running out.

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Under one black bin a month!!

I only put out 10 Black bins (general waste- most of it ending up in landfill) last year!
For a family of four who prepare most of our food from scratch- that's not bad at all!

I haven't put out any yet this year - just as well because collections are a bit behind because of weather.

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Overfed can-o-worms update 2

Still no smell from the can o worms despite its definite indigestion over Christmas. The overfed layer is still somewhat smelly (mainly a fishy smell) if it's opened up, but the worms are definitely moving through it. And maybe it's because I haven't removed any worms recently, but the population seems to be exploding despite the cooler (ok arctic) temperatures.

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Dog Poo composting.

As the snow clears from the garden, suddenly the dog poos are more visible.
I vermicompost my dog's poos, but not in my regular bins which I might in time use to fertilise or start salad crops!!
I have a hole in the ground lined with stones for drainage and a piece of weed cloth to stop solids and worms from mixing wi th the stones and soil. I started with about 250 g (half pound) of worms, a load of compost, some vermicompost with baby worms and cocoons...


I've put a platic lid over the hole to reduce waterlogging, but add some water if the contents look too dry. Every time I add dog poo collected from the garden, I cover it with a layer of leaves/ compost or some vermicompost. The hole was about a foot(30cm) deep and two foot (60cm) wide, and it was started last spring. I guess it will last me at least another year. Or lonher.In fact it doesn't seem to be filling up at all.
NOTE: I don't know if I will ever harvest castings from this bin, but if I do, I will only use them on non food crops. Although worms do seem to be able to partlydecontaminate faecal waste there is still a risk of disease
NOTE 2: I don't put poos in with worms for about 3-4 days after giving the dog her worm tablets.

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Overfed Can-o-worms update 1

Smell virtually gone today. Until I opened up and inspected the troubled tray. The smell was less than a few days ago, andthe Vermicompost seems to be deodorising it before it escapes.
The really interestingthing isthe number of worms in the really rotten layer. I thuoght they'd steer clear until conditions improved. But it is warmer in the smelly layer so maybe they're just comingup to bask!!

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Robins love potworms

It's freezing cold in Ireland at the moment. Some of the coldest weather since whenever...
So don't forget to feed the birds. If you have a worm bin, you've probably had an infestation of potworms at some time


Potworms are those tiny threadlike white or cream worms which clump together in a moist, and usually acidic area of your bin. (Damp bread and mango stones attract them in my bins.) Potworms (enchytraeids) should not be confused with baby redworms which tend to be slightly plumper, and transparent until they begin to turn pink or red. They're not a real problem in a worm bin, except that they are an indicator that conditions may have become a little damp or acidic- either throughout the whole bin, or just where they have gathered. (Although some people hate the look of them and serious worm breeders don't like the fact that they eat food meant for their worms)

If you have potworms and you want to get rid of them- place some damp bread, or other attractant and when they come to feed, just scoop them out. And as I said in the title of the post- Robins and other small birds love them, and they are an ideal and nutricios food for your feathered garden visitors.

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Overfeeding a worm bin

I overfed my can-o-worms over Christmas. It got loads of vegetable trimmings and plate scrapings but what really over did it was a tub of crab that was decidedly off, and some ham and fish that was in the fridge and had gone off. (I had decided I was really going to push it to its limits- don't try this at home unless you've been worm farming for a while and have plenty of worms in your wormery.)



Overfeeding a worm bin can be a very serious problem. Especially when you're just starting out as your total volume of bedding and worms will be lower than in a well established bin
Worms need food to rot before they can eat it, but as food begins to rot it can cause the following problems:
Decomposition uses up oxygen which the worms need to breathe. If the rate of oxygen depletion is greater than it can dffuse back into the area, worms will need to move to somewhere with more air. In a small or enclosed system, this means worms gathering on the lid, trying to escape or dying.
As oxygen is depleted, decomposition switches to anaerobic decomposition. This is the nasty, smelly type of rotting (the gag-inducing smell you get from a rancid bin). It also produces toxic substances which will harm your worms unless they have somewhere to escape to.
If there is enough oxygen for aerobic decomposition to continue unchecked, the wormbin will heat up, potentially getting too hot for the worms to survive.

When I went to get some wood in the garage this afternoon, I could get the smell as soon as I opened the door...
Surprisingly the worms were more active than in any of the other bins in the garage, despite the can o worms being nearest the garage door and probably most exposed to the cold. Given that there's plenty of uneaten material in all the worm bins, I can only assume that the can-o-worms design is allowing plenty of air through to the worms and the food and keeping microbial action going. To deal with the smell I simply reversed the trays (put the top smelly tray into the middle) so that there was plenty of vermicompost between the rotting material and the outside air. The idea of this is that vermicompost can act as a powerful deodoriser due to the bacteria present in it. I also added some finished vermicompost to the food tray to speed up breakdown. Amazingly a few hours later, there was no smell in the garage, though I didn't tempt fate by opening the wormery. I'll have another look tomorrow, then if all seems to be going well, I'll do the best thing you can do for an overfed wormery and give it plenty of benign neglect!!

Updates: 1, 2

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New Year- more blogs entries?

Not an original resolution by any means- in fact I may have included it last year. But I've added the blogger tool to my i-google page so maybe it'll prompt me to blog more often. Here's hoping!!

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