Many thanks to my friend Bentley “Compost Guy” Christie who introduced me to and got me fired up about optimization… much of what I’ve included here is inspired by his excellent work in this topic for home vermicomposters. A little additional effort in preparing your bin’s inputs yields really significant returns in speed of processing, preventing things like pests and odors, and having a thriving population of happy worms!
As we discussed in the section on feeding, most materials that used to be alive can be processed in a vermicomposter. Some take longer or require some additional care, but they all can get there. Let’s talk about what we mean by “optimizing”. Optimizing simply means some simple steps we can take to make inputs more readily digestible in the worm bin. There are two major components to optimizing: particle size and inoculation.
Particle size really just means chopping or breaking up what you’re adding to the bin. We already know a couple important facts that bear reviewing here: 1) microbes perform the initial breaking down of food scraps, and 2) worms don’t have teeth and do have teeny tiny little mouths! Consider an intact carrot: carrots evolved to be resistant to breakdown by soil organisms, since they grow in the ground. So they have a protective skin and tough flesh. Consider a head of lettuce: if put into a bin as-is, only the outer couple leaves get in contact with the bin microbes. the rest of the head inside is kind of shielded by those outer leaves. However if we coarsely chop the carrot and lettuce up, then every slice exposes more surface area to microbes for doing their thing! Don’t get all frantic about this, everything will end up breaking down, but you can give the bin a real shot in the arm by chopping materials up. And for me there’s also something satisfying about hacking up my scraps before adding to the bin. More on this in a bit.
One technique you’ll hear about is freezing your scraps solid before adding. This softens them by breaking down cell walls, and has the additional benefit of killing fruit fly eggs. I personally don’t freeze any more as it is an extra energy input and takes up freezer space, but I’m not at all saying it’s a bad practice. Many people swear by it and have great results, I just don’t have any of those issues since I started chopping and using living compost with my bedding. If you do try freezing, one thing to note is that especially for water-rich scraps like lettuce or fruits, it will release ALL the water from the scraps when it thaws so having dry bedding ready to absorb it is in order.
Then inoculation means getting those microbes mixed in and working on your food scraps. At its most basic, adding chopped scraps to the bin in thin layers and/or mixed into the existing bin materials accomplishes inoculation. What we do NOT want is to add a blob of scraps in a pile where the microbes have to slowly penetrate and invade the foods: this leads to the un-exposed materials on the inside of the pile being vulnerable to pests like fruit flies or putrefying before our “good” aerobic microbes can establish. To inoculate at the "master" level (which is actually pretty easy), one uses some form of living material as/with bedding and just mixes it into the chopped scraps, coating the surfaces with microbe-rich bedding and then the mix goes in to the bin. The worms can then move right in to the materials as soon as the microbes have established and worked their magic.
So the take-home on optimization is that if you’re willing to do a little bit more than just dumping scraps in and covering with bedding, you can take a HUGE step forward in processing power.
For my indoor bins, here is my process: I start with a vessel (I use a rubberized farm tub), and add a layer of bedding and/or living material in bottom of the tub. Then I dump the food scraps onto the bedding and grab a chopping tool, my all-time favorite is an ulu but a knife, pizza cutter, or the like works fine. I coarsely chop until the scraps and living material is thoroughly mixed, and especially any tough woody or bulky chunks are all reduced to about matchbox-sized or smaller. Again this isn’t something to get your blood pressure elevated over (unless you’re like me and the chopping is meditative for you!). Thoroughly chop and mix until the addition is more or less uniform and most food scraps have some bedding/living material coating their surfaces. Then just moisten if needed, layer on top of the bin surface, and if you wish cover with bedding/paper/burlap/whatever you use. The only difference in my outdoor windrow is that I use a bigger rubber tub and a shovel or a machete for the chopping!