The Best Composters for Kitchen Scraps
If we were looking for a low-maintenance composter for your yard, we’d get Earth Machine (~$90), a composter that’s big enough for most households and often available at a substantial discount from local Public Works departments. It’s easy to assemble without tools, the top opens large enough to stir and aerate the compost (or dump in a whole watermelon), it keeps rodents out of your compost-to-be, it holds together well over time, and it’s made of at least 50% post-consumer recycled polyethylene. The open bottom allows your compost-assisting worms to snuggle into your pile, and you can attach the Earth Machine to the ground with included screws or tend stakes to keep compost-consuming raccoons from knocking it over. Overall, it’s cheaper, simpler to put together, more secure against pests, and more ecologically friendly than other composters.
And finally, we know not everyone has the space for a full-sized composter. If you don’t have a yard, a small compost tumbler like the Forest City Tumbling Composter with Two Chambers (~$110) will let you compost on the porch, while indoor composters can use the Worm Factory 3-Tray Worm Composter (~$80).
Table of Contents
Who should buy this? | How we picked & tested | Our pick | Flaws but not dealbreakers | Runner-up | A step up | A step down | Best indoor compost system | Types of composters | Outdoor bins | Compost tumblers | Worm bins | Motorized electric composters | Private compost services | Competition| Theory and practice of compost | Wrap-up
Who should buy this, and should I upgrade?
Compost is what you make of it. No, really! If you have a system for making compost that works for you, don’t change.
Consider upgrading to a different compost system if you’re having problems with rodents, maggots, or other pests (bears?) getting into your bins or if your current composter is too small to handle the increased amount of kitchen scraps from your new all-watermelon diet. If you’re having problems with compost odors, you should try changing your composting practices to get more air and “browns” into your pile. (See Theory and practice of compost.)
How we picked & tested
The best type of composter for your household depends on why you’re composting and how you’re going to do it. People compost for many reasons: to keep food waste out of the garbage (reducing your garbage bills *and* making your kitchen smell better!), to make fertilizer for their gardens, or just because they like worms. Some people hate worms. People who want to watch what happens as their compost breaks down will need a different system than people who don’t really want to touch the stuff. As Chicago garden expert Ramon Gonzales, aka MrBrownThumb, told us via e-mail, “The best indoor and outdoor compost bins are the bins that are actually going to be used.”
As part of my research, I divided compost bins into three categories: outdoor bins (best for lazy composters—that is, most of us), compost tumblers (best for critter problems), and indoor systems (best for city dwellers and people who avoid dirt). The type of composter you should get depends on the size of your household, whether or not you have outdoor space, how much work you want to put into it, and how persistent compost-hungry creatures are. (Read Types of composters for more details.)
I looked at the bins’ structure, reported flaws, and costs. Important factors included:
- Doors. Composters with hinged doors with clasps are easier to open and close than lids that screw on. Screw-on lids also tend to get clogged with compost fragments over time.
- Access to finished compost. A small hinged door may be fine for putting compost into a bin, but it can make it difficult to get compost out.
- Capacity. Small households can’t use a compost bin with a cubic yard capacity if they’re not composting yard waste.
- Pests. Persistent rodents can gnaw through any plastic if they’re determined enough, but some bins are easier to retrofit with gnaw-proof wire mesh than others.
If you want to build your own bin, you can make a garbage can composter, which is exactly what you think it is, for somewhere between $15-$60, depending on materials. A 3’ x 3’ x 3’ open-top Slatted Bin Composter can be made for ~$140, based on prices for the lumber on Home Depot’s web site. Of course, those calculations assume that you already have access to a power drill (and that you enjoy using it).
If your muncipality isn’t so generous, you can still buy an Earth Machine at Home Depot. And there are good reasons to do that. It’s easy to snap together without tools. Users praise the raccoon-resistant screw-off lid and the Earth Machine’s generous size (80 gallons), which should keep a large family’s compost contained for months. (Remember, as the compost matures, it will shrink to between 10% and 40% of its original volume.) Plan to empty out your delightful finished compost twice a year.
The Earth Machine is made of at least 50% recycled polyethelene, which is tough, and it’s sturdy enough that users don’t complain about the sides bulging or bowing out when it’s loaded.
By all reports, it’s easy to put together (I put one together myself in past years), and it’s easy to attach to the ground with long stakes (that, yes, are included). One Home Depot reviewer was a bit more jaded, saying, “It’s a barrel with holes. Not too much say.”
Flaws but not dealbreakers
Rodents can chew through the polyethelene. Users suggest putting hardware cloth under the Earth Machine’s open bottom to keep rodents from tunneling up into the compost. Use hardware cloth instead of, say, a piece of plastic to let the composter’s excess moisture drain, and to allow worms to move up into your compost—which they will do, far more quickly than you expect, speeding your compost along and making taking out the kitchen scraps a much, much more attractive chore for young children.
In theory, the bottom door should make it easier to remove finished compost from the bottom of the Earth Machine. In practice, it’s too small to easily fit a shovel, and the door can get stuck open. Most Earth Machine users I know and read on Garden Web simply pick up the composter once a year, shovel off the unfinished compost on the top, then move the finished compost below to their garden beds. That’s all most users need to do because compost shrinks in volume as the plant structures break down and water transpires away (as it “cooks,” if you will).
As I wrote above, ultimately, whether a composter works depends on the owner. Sure, the Earth Machine can emit nasty odors if you put raw meat into it or if you never add any dry, brown materials like sawdust or leaves. If you never aerate the compost by turning the stuff inside the bin over or pushing a broomstick into the pile, or if the pile dries out, it will take a long time to mature, and you might fill your bin to capacity. But all that’s up to you. The Earth Machine is as high- or low-maintenance as you make it (or can stand).
The small doors on the lid flip up and secure with a snap instead of screwing on, but if you’re putting in larger items, the top can’t be removed with one hand, according to this survey of Garden Gourmet users in Vancouver. Otherwise, it’s also an open-bottom composter that sits on the ground (remember to put down that hardware cloth). It’s as eco-friendly than the Earth Machine, as it’s made of “at least 51%” recycled plastic.
The Garden Gourmet holds slightly more stuff than the Earth Machine (11 cubic feet vs 10) and is a few inches taller (40” vs. 33”). Its sides don’t bow out when it’s loaded properly. And, like the Earth Machine, the Garden Gourmet’s lower hatch for removing compost is a source of complaints.
Best compost tumbler
The galvanized steel keeps animals out, and to discourage particularly clever animals (raccoons, your upstairs neighbors) you can put a lock on the metal door clamp. Yay! You can fill one side with stuff while you’re simply turning the other side. Well-spaced handles on every other side of the tumbler make turning easy.
The insulation keeps the pile warm once it starts to heat up, enabling hot composting of much smaller amounts of materials than a cubic yard. Users report, “I just went out to empty the container and when I opened the Jora STEAM CAME OUT … (I might add that the temp was in single digits this week!) If I could add a 6th star at this point I would do so.” and “On a hot day this summer I measured the temperature of the compost in the Jora as 161 degrees Fahrenheit!”
The Joraform is also easy to unload. Put a tarp down under the tumbler, crank it so that the doors are facing the ground, then open up the side you want to unload. Tah-dah! Watch out for falling compost!
Several reviewers note that it takes two people and a power drill to screw a Joraform together and that the confusing assembly directions aren’t translated well. One commented, “It’s obvious that they were translated from Swedish into British English, as the tools it recommends are spanners (wrenches) and a cross slotted screwdriver (Phillips head). Ignore the text instructions completely and rely totally on the diagrams (which aren’t the greatest, either).”
Although the Joraform composters’ galvanized steel sides repel rodents, small insects can get in through the side ventilation holes. You will probably have fruit flies move in during summer months. Such is life.
Note: Don’t bother with the smaller Joraform Compost Tumbler JK 125 ($300). At 125 liters (28 gallons / 4 cubic feet), it’s not as successful at retaining heat, no doubt due to its larger surface-to-volume ratio. One Amazon reviewer observed, “The place where I bought mine stated that the insulation allowed it to keep working to -20 F. Not even close. It quits working when it hits just a bit below freezing.” If you really want a completely airtight, rodent-free, leakproof tumbler, this might be a good choice for you—but it won’t make compost any faster than a cheaper tumbler, and $300 can buy an awful lot of hardware cloth and drip trays.
It’s small for a composter: 37 gallons, five cubic feet, 36” x 28” x 26” (HWD). By comparison, the Joraform holds 61 gallons and the Earth Machine holds 80 gallons (remember, compost matures much more slowly in non-rotating composters). It’s not the ultimate composter by any means. It’s not insulated, and it’s small, so it won’t heat up like the Joraform, and its plastic is “rodent resistant,” which means that determined rats will chew through it. (Amazon reviewers suggest covering the vent holes with wire mesh.) Those large air vent holes also let in liquid; be prepared to put in more dry brown materials as necessary. The doors are a bit small for unloading with a shovel, but the if you turn it upside down over a tarp, it should empty out nicely.
Best indoor compost system
The Worm Factory is just a stack of plastic boxes with holes in the bottom, a lid, and a sealed bottom layer with a spigot for draining liquid; you could make your own worm bin out of your own plastic boxes and a drill if you like. But The Worm Factory’s bins fit together well, and the multiple layers make it easier to separate the worm castings from the worms, because the fine-grained castings fall to the bottom bin while the worms migrate upwards when you add a new tray of food and bedding. (See worm bins for more details about worm bin use and harvesting castings.) For many people, not having to handle hundreds of worms to remove the compost is more than enough reason to buy this bin.
Compared to the Worm Factory, the highest-rated mechanical indoor composter (the NatureMill Indoor Composter) is expensive, has a tricky list of acceptable materials (broccoli is verboten!), and relies on many small electrical parts which will eventually break. Bokashi buckets, the most common non-mechanical indoor compost method, don’t actually break down materials into compost (more on that below).
It takes time to build up a worm population large enough to eat the scraps of a four-person household, so this system may not be right for big families. Sweethome editor-in-chief Jacqui Cheng uses a Worm Factory system in her Chicago condo for two adults who cook almost all meals at home, and says that it’s just the right size for her household, if not a little small. If you have more than a few people generating a lot of kitchen scraps, your worms could get overwhelmed—and that’s when the odors begin.
Keep in mind that you can’t (or at least, shouldn’t) fill your worm bin with everyday earthworms from the back yard. As one Slate reviewer put it, “Apparently they have a thirst for freedom that is not desirable for creatures you’re planning to keep in a box in your kitchen.” Worm composters use red wiggler worms. You can find them at many garden centers and tackle and bait shops or even online at certain retailers, like Amazon. (Yes, you can receive live worms in a box in the mail.) But worm gardeners love to share, so it’s easy to ask around and see if anyone will give you a handful of worms from their own bin. Sometimes you can even ask on Craigslist in the gardening section, and people will give them to you for free. The wigglers reproduce rapidly once they get started, so you’ll have a full bin eventually.
Types of composters
“Compost Happens,” the bumper stickers say, which is true, sort of (like all things cars say on their rear ends). Compost only happens when certain types of bacteria break down organic matter. To keep those bacteria happy, you need to be able to get those bacteria the right amount of air and water, and enough dry “brown” material that they’ll be able to digest your kitchen scraps without making a stink (See Theory and practice of compost). To make them ecstatic, so they’ll break down your compost in a hurry, you need a compost pile that’s big enough for “hot composting,” where bacteria action can heat the pile up to 120º-160ºF (50º-70ºC), killing weed seeds and sterilizing diseased plant matter in the process. That approach generally requires a cubic yard of compost, so it isn’t for everybody. City-dwellers need a small, self-contained system to handle their scraps on a porch or even in the kitchen.
While you want to keep your bacteria happy and full, you don’t want to feed the local rodent population in the process. A compost bin needs to keep your kitchen scraps safe from varmints. Depending on where you rot your veggies, you may find that mice, rats, possums, raccoons, and heaven knows what else will visit your bin. If you put a layer of dry “brown” materials like dry leaves or sawdust in your bin after every batch of kitchen scraps, you should eliminate your compost’s smell and deter invaders. Still, a compost bin should be strong enough to withstand some animal assaults, though perhaps not bears.
A compost bin shouldn’t smell bad. That’s mostly dependent on the person putting materials into the compost, not the bin itself, but a good bin should make it easy to keep your pile smelling sweet by keeping the right amount of air and water in the mix.
Pros: low maintenance, large capacity; can keep adding waste on top as bottom materials finish composting.
Cons: Can be slower to finish compost than other methods you don’t turn/aerate regularly.
Outdoor compost bins are often just barrels with holes. They sit on the ground, and their open bottoms let the worms crawl in, the worms crawl out, and excess moisture to drain. They’re good for larger households and for people who want add some yard waste (dry leaves are great!)
There are two categories of outdoor bins:
- Open-top bins (commonly made by DIYers out of wire or wooden slats or pallets) are easy to build, and you can make them as large or small as you like. They’re easy to access for turning and aerating the pile, but rodents and insects have access to them too. They’re best if you have a large yard with lots of space.
- Closed bins are usually purchased, or made by drilling holes in a garbage can. They’re tougher for rodents to enter, but may be harder to aerate, depending on the size of the lid. They’re great for smaller yards in more urban areas.
Pros: it’s easy to get more air into your compost, making tumblers much quicker at finishing compost. They’re less likely to attract rodents than on-ground bins.
Cons: They’re expensive, they often leak excess moisture (some models have trays to catch the “compost tea”) and can be hard to turn if they’re fully loaded. At some point, you need to stop putting new materials into your tumbler and start turning it to make finished compost.
Tumblers are big cylinders or spheres that rotate to mix up your compost. They come in four different types.
- Crank-operated tumblers are a big drum on a frame with a crank sticking out of one end, and work like bingo machine; turn the crank on the side to rotate the drum around its long axis. They’re stable, and can handle heavy loads.
- Center-axle compost tumblers are “more like an over sized plastic pill capsule,” as Compost Junkie writes, generally with a bar through the center of the capsule on the short axis. They rotate end over end, kind of like Sandra Bullock in “Gravity.” They usually have doors at either end and are easy to unload.
- Base-rolling tumblers sit on a base with some kind of rollers. You can rotate them by pushing with your feet or bending down to turn them with your hands. They can feel heavy and hard to turn.
- Spherical or “Death Star” composters, which are giant plastic balls. You either turn them on a base with rollers, or kick them around your yard to leave a swath of galactic destruction—I mean, mix the contents.
Compost tumblers do have some distinct advantages. Gonzales comments, “People that are a little lazy may benefit from tumbling composters, and they’re probably the best choice for people who can’t commit to turning a pile of compost on a regular basis. And for people who may live in areas with a lot of critters that can get into a compost pile, because they’re usually up and off the ground and enclosed.“
Pros: Great for apartments and small households. You get to have pet worms!
Cons: You get to have pet worms, which means paying some attention to them—not much, but some. Limited capacity; best for smaller households.
You put food scraps into your bins, add more dry material if it gets smelly. Worms should be fed every 2-4 days, but as the Urban Worm Composting site says, “Worms are flexible… If you go on vacation, your worms will be fine for a couple of weeks without care–assuming you give them a big helping of food waste before you leave, and their bin doesn’t get too hot or dry.”
Worms eat fruits and vegetables and produce (that is, poop) worm castings, which are excellent fertilizer. A worm bin is just a big box with a lid for the worms, their bedding (shredded newspaper or leaves), and their food. The lid needs to have air holes, but that’s about it. Cornell University publishes a clear, short guide to worm composting, while the New York City Department of Sanitation has a more detailed worm compost guide. Worms seem to form part of a New York state of mind.
After a few months, you harvest your worm castings. You have two options: you can use a slow, gradual method of persuading the worms to move away from the castings, or you dump the pile on a tarp, take off the top layer of castings as the worms move away—and then pick the worms up and put them back in! Whee! Don’t wait up for me, Momma, I’m cleaning out the worm bin tonight! Good times.
As I noted above, stacked bin systems like the Worm Factory 360 take some of the excitement out of cleaning worm bins by encouraging worms to migrate upward away from their castings. You just take out the bottom bin and empty it. No wriggle-party, but no fuss.
Motorized electric composters
Pros: Clean, fairly easy to use, no worms, allows meats, fats, and dairy.
Cons: Expensive, limited capacity, unclear how long the mechanics will last.
The NatureMill, the one electric composter we looked at, comes complete with an automatic mixer, a fan, and a heater; you can see a diagram of its insides here. This is the composter of last resort for urban-dwellers who can’t stand the idea of worm bins.
It takes ~5 kWh of electricity a month to run. The NatureMill comes with a packet of sawdust pellets and a small amount of baking soda to “balance the pile,” and instructions about what to put into this somewhat quirky system. Unlike every other compost system, the NatureMill will happily absorb the meats, fats and dairy products that other compost systems eschew. However, fibrous vegetables like celery will clog its delicate mechanisms, broccoli is too smelly in large quantities, and citrus fruits can kill the NatureMill’s bacteria. Got that? Think you’ll remember it after you and your boyfriend finish off that bottle of wine at dinner tomorrow night?
The bottom line is that it does seem to work, and might be a good alternative for urban dwellers who want to keep their food waste out of the garbage, don’t want to bother with the annoyances of a worm bin or bokashi system, and don’t have municipal food waste collection or a local compost hauler like Bootstrap Compost. It sounds like a yuppie appliance straight out of Portlandia, and as a Gizmodo reviewer put it, “It’s an industrial machine for a primeval process. And it works.” Still, if you just want your food waste to go away, it’s a legitimate alternative.
Private compost services
Pros: takes little to no effort, monitoring, or space.
Boston’s Bootstrap Compost and Black Earth Compost, Washington, D.C.’s Compost Cab, Los Angeles’s L.A. Compost, and many other firms will take away your food scraps and bring you finished compost for a fee. It’s not cheap; expect to spend $8 a week or more. But you’ll get rid of your food waste without touching worms, or worrying about putting enough leaves in your pile, or turning a single crank. Remember, the best composter is the composter you actually use; and if you want to use healthy young compost haulers to tote away your orange peels and coffee grounds, so be it.
We don’t recommend bokashi buckets, which are basically a five-gallon plastic bucket with a lid and a spigot on the front.
To use your bokashi bucket, you put in kitchen scraps and doses of bokashi bran, bran which is inoculated with the special bokashi bacteria that supposedly digest your scraps more quickly and thoroughly than the stuff that’s already living on your banana peels. Every day or two, you drain off excess liquid via the spigot to keep your bokashi from descending into anaerobic oblivion. You keep layering scraps and bokashi bran until the bucket is full, or until it’s smelly and moldy-looking enough that you give up and just throw the whole thing out.
What then, you may ask? What do you do when the bucket is full? Why, you let it sit in a closet for two weeks to cure. Then you can take it outside and put it in your real compost heap, or bury it in the ground for two weeks to complete your compost… you know, in that yard you don’t have.
If you have a favorite community garden or suburban friend you visit once a month who might appreciate compost, a bokashi bucket could be a convenient excuse to visit them. Otherwise, you’ll just be hoarding scraps around to throw out later.
The Algreen Products Soil Saver Classic Compost bin ($85) is another well-respected “barrel with holes” composter. The lid locks with two side plugs, which can be opened one-handed for throwing in a few small scraps, but otherwise you’ll be taking the entire top lid off with two hands. Assembly is easy with no tools, and there’s a bottom door for attempting to remove compost. However, a substantial minority of users complain about the top lid not fitting properly. For the price, the Earth Machine is a better bet.
The Concord Recycler Compost Bin ($99 for the 89-gallon size: $165 for 157 gallons) really is a barrel with holes! No bottom door, no screw-top—just a plastic tube with a lid on top. Unlike the other outdoor ground composters, it comes with an optional bottom lid as well. If you want to isolate your compost entirely from the ground, just set it on top of the lid. Having the bottom open and sitting on hardware cloth is a better alternative for moisture management and worm access, but if you want to put a large composter on pavement, and you don’t want to use a compost tumbler, the Concord Bin could be a good alternative.
The Geobin Compost Bin ($30) is topless! That’s fine on the French Riviera, but this “compost bin”—which is really just a giant piece of plastic you roll into a tube and fasten on-site—will put your kitchen scraps at the mercy of vermin. If you’re not going to put a camouflage layer of leaves, sawdust, straw, or some other “browns” on top every time you dump kitchen waste in your bin, skip it. It can expand to hold just over a cubic yard of material (28 cubic feet), making the pile big enough for hot compost. Hot compost! Maybe it really does belong on the French Riviera.
The Dura-Trel 90 Gallon Vinyl Mocha Compost Bin ($140) is made out of PVC, and looks it. It also doesn’t have a top. For the same amount of money, you could build a cool-looking cedar plant bin that doesn’t have a top instead… or for $110 less, you could get a Geobin.
The Good Ideas Compost Wizard Dueling Tumbler ($146) does not actually send fireballs at challengers like most dueling wizards, as one Amazon reviewer observed. It’s a two-chamber plastic tube on a base that holds 50 gallons (7 cubic feet) of, well, anything. It doesn’t have a handle. You either grab the hand-holds or push it with your foot or some other free body part, and it rotates on wheels embedded in the base.
What the Good Ideas Compost Wizard does have is an enclosed base for collecting the brown liquid that will ooze out of its air holes, and a spigot for collecting that liquid—also known as compost tea—so you can water your plants with it. That’s an advantage… if you can get the compost tea out of the spigot, which means that you should really put it up on cinder blocks so you can put a watering can underneath it. But then it’ll be harder to turn it with your foot because it’ll be raised up off of the ground (though not far enough to be easy to turn with your hands), and it will already be hard to turn once it’s fully loaded. It also has a twist-off lid, which you will need to clean periodically to keep compost fragments from gumming up the threads.
The Envirocycle Original Composter ($180) a 52-gallon base-rolling compost tumbler; a smaller Mini version ($120) holds just 17 gallons. Like the Good Ideas Compost Wizard, it sits on top of a plastic box that collects “compost tea,” aka the liquid that oozes out of your compost tumbler. Unlike the Good Ideas Compost Wizard, it has just one chamber, so there’s nowhere to put your next batch of compost-makings once you fill it up. On the bright side, its doors attach with a metal hook, not a twist cap, so you won’t spend as much time cleaning compost off the door threats with a toothbrush, which isn’t a task that’s even fun to imagine. Garden boy calls it “simple, sturdy, and smart,” while Crazy about Compost stays it’s “the best compost tumbler available“and Amazon reviewers praise it for how easy it is to turn and the fact that there’s no assembly required. A New York Times reviewer commented about the Envirocycle Mini, “It seemed to hit a sweet spot — unobtrusive enough that neighbors would not mind seeing it in a shared outdoor space, but not so nice that someone would likely steal it.” However, a few reviewers note that that metal hook fits very tightly and can be hard to unlatch, and that if you forget to empty the compost tea, it will overflow—removing the whole point of the compost tea collector.
Overall, if you’re looking for a hands-on low-to-the-ground compost tumbler with a closed base, the Envirocycle is a great choice. Unfortunately, its single-chamber design means that many users will end up either throwing away kitchen waste for several weeks when the composter fills up, or buying a second composter, which is why it isn’t a main pick.
The 58-gallon Tumbleweed Compost Tumbler ($187) looks like a giant rotating trash can. It has screw-on lids at both end, so you should be able to get it open even if you forget to clean the threads a few times, but, dang! It’s ugly. There’s a black version if you want to try to make it slightly less conspicuous. You’ll also need enough clearance to spin your new garbage can around on the long axis (pitch, to you naval composters). For $187, you could get two $90 Forest City compost tumblers for a total 64-gallon capacity and still have enough money left to go buy a beer at the Garden Bar where everybody knows your name, your composting method, and your favorite trowel.
The Algreen Terra Tumbling Composter ($207) is another compost tumbler with a center divider. It holds 55 gallons (7.35 cubic feet), and is made of curvy smooth plastic in one of three colors that begin with b: black, brown, or brick. Amazon reviewers admire it, although they also mention that it leaks fluids. For $27 less, you could get two of our pick, the Forest City tumbler, for a total capacity of 74 gallons. It wouldn’t be brown, or brick—just black—and the Forest City definitely has a more Star-Trek design aesthetic than the earth-mother Algreen composter.
If, for some unfathomable reason, you prefer to turn two compost batches separately, you can purchase the Gardener’s Supply Dual Batch Tumbler. For $160, you’ll get less total capacity than the Forest City (22 gallons total vs. 37/ three cubic feet vs. five) and gain the ability to turn the chambers separately. If you think you might not be strong enough to turn a small compost tumbler, it might be worth it. But for most home compost-makers, spending an extra $70 to get a smaller composter doesn’t make sense.
The STC CompoSpin Composter with Rolling Base, 50-gallon ($214), aka the “Death Star” composter, is a big ball on rollers. It looks charming to all right-thinking citizens of the Galactic Empire, but there are consistent complaints about the doors permanently locking shut. As one reviewer wrote, “Both the roller pins and the holes get totally gooped up with soupy compost and when you are lucky enough to get the lid loose, you need to rinse off both the lid and the holes in the composter with a hose or it is really tough to get the lid back on.” If you don’t want to spend time cleaning your composter—and who does?—skip it.
The Vermitek Worm Composter, 3-tray, Black ($69) looks to be pretty much identical to The Worm Factory. Unfortunately, Vermitek’s offerings were almost out of stock on Amazon when I was researching this piece, and Vermitek did not respond to e-mail or phone calls about how soon they’d be back in stock. At least, I think Vermitek didn’t respond to phone calls. When I called the number listed at the Vermitek web site for the main office twice, all I heard was a voice saying “Please leave a message” —not “Welcome to Vermitek!” or “Listen to The Sound That’s Made By Worms.” Who knows who I contacted? I never heard back. Consider carefully whether saving $11 over the Worm Factory is worth relying on Vermitek’s vaporous business presence.
A round worm bin option is the Triformis Can-O-Worms ($147). It’s black, and only has two layers or working worms. It stands on fairly tall legs that some reviewers find are weak, or buckle under full wormloads, or make the Can-O-Worms unstable and prone to tipping over. The replacement trays for the Can-O-Worms are also much more expensive than the Worm Factory’s replacements ($45 vs. $8). Instead, opt for the expandable square Worm Factory which will fit better in a corner anyway.
We don’t recommend bokashi buckets, like the KTP B100 All Seasons Tan Bucket Indoor Composter ($23) (also available as the $43 SCD Probiotics K100 All Seasons Indoor Composter Kit, Tan Bucket with Bokashi if you get it with bokashi bran), the $69 Sunwood Life Bokashi Compost Kit, the $45 All Food Recycling Compost Kit with Bokashi, and the $69 Bokashi Compost Kit. Bokashi buckets ferment your scraps, but they still need to be finished outside to be turned into compost.
Theory and practice of compost
At its most basic level, compost is made of rotted plants. Take a bunch of kitchen scraps and leaves and throw them in a pile on the ground, and sooner or later bacteria, fungi, worms and insects will break it down into something that looks like dark-brown soil and smells like a forest after a rain. That’s compost.
To make good compost without stinking up the neighborhood with decomposing garbage, you need to become a farmer; a bacteria farmer, with a gazillion million head of very tiny livestock. Bacteria are what make your old onion skins and banana peels into “black gold,” and if they’re not happy, your pile will smell terrible, or just sit there.
You need to control how much air and water there is in your pile, and what you put in it, to keep your microbes—and your downwind neighbors—happy. That said, it doesn’t take much time or expertise to make compost. Once you have a feel for how compost works in your yard, you can make good compost slowly in a few minutes a week. If you want to speed things up, you’ll need to do more work.
To get enough air into your compost, you can “turn over” your pile from time to time by remixing it with a shovel or garden fork. If you’re feeling less energetic, take Brooks’ advice: “Get a broomstick, stick it in [your compost], and rotate it…Make big circles.” Do that a couple of times a week, and you’ll have biceps bigger than Vidalia onions and finished compost in 6-9 months, Brooks said (except for the biceps part.) If you don’t bother with this, you will still get compost…eventually. If you’re not in the market for biceps, you can get some air into your compost simply by throwing bulky items that will form air pockets (sticks!) into your bin as you’re loading it.
Compost should be about as wet as a wrung-out sponge. Pick up a handful of materials from your pile. (Go on. You know you want to.) It should feel damp, but you shouldn’t be able to squeeze any water out of it. That translates to a moisture content somewhere around 50%, which is what happy bacteria prefer. Alternately, you can calculate the moisture content of your pile if you know exactly what’s going into it, but that sort of fun is generally only available to municipal compost managers. To get the right moisture balance, for every one part food scraps, put 2-3 parts dry material into your compost.
Then, you can worry about the carbon/nitrogen ratio in your compost… but only if you want to. In simple terms, your compost gets nitrogen from fresh “green” materials like kitchen scraps, grass clippings, and coffee grounds, which aren’t really green, but have a lot of nitrogen, and may be available at a coffee shop near you. Carbon comes from “brown” materials like dry brown leaves, sawdust, wood chips, or paper. The microscopic critters in your compost use carbon for energy, and nitrogen to build new cells. Too much nitrogen makes your pile stinky, too much carbon makes it inert. Confused? Here’s a good list of what to put in your compost from Organic Gardening to follow, and details about the biology involved. Or you could just follow the one part food scraps/2-3 parts dry material rule, which will give you a good approximation of the right ration, ‘cause dry stuff tends to be high in carbon anyway.
Frankly, you can tell if your compost has a good carbon/nitrogen ratio just by taking a good whiff. Does it smell bad? It isn’t getting enough air or carbon. Throw in a bunch of shredded cardboard or paper, stir it up, and sniff it again in a few days. You should be covering every batch of kitchen scraps with brown materials anyway to keep your pile from getting smelly, especially in bear country.
Those of you who didn’t get enough match fun out of the moisture equations can immerse yourselves in details about C:N ratios on the Urban Garden Center’s Guide to Small Batch Composting.
Some garden catalogs talk about compost activators and compost inoculators. Compost activator is just a garden supplement with a lot of nitrogen, which you won’t need if you’re using kitchen scraps. Compost inoculator is bacteria that digest organic matter, which you also won’t need if you’re using kitchen scraps (unless you only eat boiled vegetables). Just put your browns and greens in a pile and let your bacteria get to work.
Tend your bacterial herds well, and you’ll do a fine job of making cold compost. Your compost will decompose slowly over several months, shrinking as the green materials are devoured by microorganisms. However, if you make your pile big enough, and it has enough oxygen all the way through, you may create hot compost. When your bacteria get really excited, and the pile is large enough to hold in heat, your compost’s temperature will rise to around 120º-170º F (50º-75º C) and fast-acting heat-loving bacteria will take over your pile. DO NOT PANIC if you notice something like smoke rising from your compost; it’s steam.
Hot compost is a fine thing because it decomposes *very* quickly, and it kills plant diseases and weed seeds in your compost. However, it takes a lot more work than cold compost, and usually requires starting with a pile of materials that takes up least a cubic yard (3’ by 3’ by 3’, or .76 cubic meters.) There are plenty of hot compost instructions on the web if you’re curious.
In the end, no matter what method you choose, you’ll end up with dark brown, crumbly stuff that plants adore. Remember that compost is not soil. It doesn’t have sand, clay, and other mineral components that you’ll find in the ground—but as many compost makers know, plenty of plants are happy to grow out of a compost heap. I’ve seen tomatoes, pumpkins, potatoes, peaches, and avocados happily sprout out up of my family’s open-top bin.
If you have a yard, get an Earth Machine, put plenty of dry brown materials in it, and you’ll be set for compost for the foreseeable future. This “barrel with holes” is simple to use and widely available at a discount from local governments.
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