Review: Reencle Prime

“Which one is which?” my husband asked, peering at the side-by-side maidenhair ferns in 6.5-inch pots I’d left on the dining room table. One had been planted in regular hardware store potting soil, the other in a mixture of potting soil and compost made from the previous month’s kitchen scraps. “The one on the left,” I said, gesturing to the shorter, yet visibly fuller, fern. It wasn’t hugely larger than the other one, but it did look healthier.

The size of this victory depends on one’s experience with the compost process—and in-home electric composters—in general. While throwing excess food outside in a pile and letting it decompose naturally is older than … well … dirt, countertop solutions designed for kitchens have been growing in popularity the past decade or so. Which is no surprise given that up to 40 percent of food produced in the US is wasted, most often ending up in landfills, where its decomposition results in a significant release of heat-trapping greenhouse gases.

The ideal composting situation is generally understood to be a municipal program, which not only keeps waste in its community of origin, but provides local jobs for its collection and processing. However, for those (including myself) who live in areas without municipal compost plans, it's hard not to wonder whether electric kitchen composters are worth the considerable outlay of cost and kitchen real estate, or yet another corporate greenwashing fad.

Turning Up the Heat

I first set out to investigate the world of these appliances by testing the Mill Food Recycler (6/10, WIRED Review), Nest cofounder Matt Rogers’ $999 kitchen bin that grinds and dries kitchen scraps to either be used in your yard or shipped to Washington state in a plastic-lined box. While the resulting food grounds can be spread in the garden with some work, they are simply smaller, shelf-stable versions of whatever you put in the Mill to begin with—there’s no anaerobic decomposition process or cultivation of beneficial bacteria. What if one wanted real, usable compost for their trouble?

Back in 2022, WIRED contributor Richard Baguley reviewed several machines that claim to do just that—including the same version of this Reencle Prime, which was given the piece’s highest rating: an 8/10. I thought the machine was worth revisiting over a longer test period and, as I had attempted with the Mill, using the compost in the course of regular gardening.

The New York Times’ Wirecutter did something similar late last year, going so far as to have the compost output of each machine tested. (The Reencle material, for what it’s worth, got the highest marks in the test for carbon dioxide respirometry, which measures the overall biological activity in the soil.)

However, for the planting experiment, I chose to plant seeds, which is possible but generally not advised by gardening experts due to compost's not being sterile. For that reason, I chose the only two young-adult plants I could find in late winter at my Southwestern Washington garden center that seemed similar enough in height, health, and appearance—the maidenhair ferns. Using Ferry-Morse’s indoor LED bamboo growhouse ($80), I placed the ferns side by side in their respective potting mixes and waited 30 days.

Second Chance

But, back to the Reencle itself, which I've now been using every day for three months. As a kitchen appliance it's remarkably unobtrusive, a 14 x 15 x 22-inch box available in black or white with an AC plug and 6-foot power cord. It arrives with a starter bag of ReencleMicrobe—largely sawdust, activated carbon, and Bacillus bacteria. There are buttons on the top for Power, Dry (for contents that make the mix too wet), Purify (to neutralize smells), and to manually open the lid, though there's also a sensor.

To begin, open the starter bag of ReencleMicrobe, dump it in, and add about 7 cups of water. Wait 24 hours for the bacteria to activate and you're on your way. So long as the device is turned on and gets fed regular food waste, your new Bacillus buddies will continue to breed and thrive inside the mix. Keep in mind that if you don’t cook much, the Reencle will require a bit more maintenance—the ideal amount of scraps to add is 1.5 pounds per day, with an advised maximum of 2.2 pounds. During periods where my family subsisted on takeout or leftovers, the mixture became dry and the paddles began making groaning noises. Adding a couple cups of water tended to fix the problem.

There's a three-layer carbon filter (included, but $35 for a refill, which lasts about a year) that prevents smells from escaping the bin. However, at first there definitely was an odor every time the lid was opened, which could best—and unfortunately—be described as whole wheat bread baked in an anus lined with gym socks. This was exacerbated by the fact that the lid-opening sensor was extremely sensitive, and required some maneuvering to find a position where it wasn't opening all the time. The Purify button did little in the way of mitigation. This experience greatly lessened as the bacteria colony matured, and now, three months in, only a slight whiff of sock is detectable when leaning directly over the open lid.

Unlike other recyclers like the Lomi and Vitamix FoodCycler and even the Mill, the Reencle runs continually and stays heated to 131 to 140 degrees Fahrenheit, so waste can be added at any time and starts to break down immediately. I initially worried about power expenditure with this process, but the machine never topped 3 kilowatt-hours per day, as confirmed with a power meter.

Most food items are broken down into unrecognizable particles within 24 hours, and the microbes can consume anything a person could reasonably digest. Meat is OK, as are fruit peels, eggshells, and even small bones. Keep in mind, though, that there's no grinder, so while this means the operation is quiet—I only ever got about 5-10 decibels more than Reencle's claimed 28 dB—it also means larger items like banana peels or whole fruits must be chopped up.

It took my regularly home-cooking family of three about three weeks to get to the "max" line on the inside of the bin, but this time could vary wildly. To extract the compost, one needs to scoop it out with the included shovel (there's a hanging peg for it on the side) and sift out the larger pieces.

Aggravatingly, no sieve is provided for this, but many people on the learning-curve-flattening Reencle Composting Community Facebook group recommended this $17 sifter from Amazon, which did the trick. (Any sifter will do, so long as the holes are larger than a colander's.) The sifting was admittedly a messy, time-consuming process, after which the compost needs to be mixed at a 1:4 ratio with potting soil and cured for three weeks in a “breathable container.” I used a plastic bin with the lid slightly ajar.

During the testing period I took a weeklong trip, and suspending the Reencle's operation for a vacation was easier than expected. The instructions suggest stopping adding scraps three days before, running it on “Dry” for two days, then unplugging it, all of which I did. It was no worse for wear after a week away—no mold, no bad smells. Reencle says no modifications are necessary for trips shorter than a week, but given that mine makes noises if it gets too dry, I didn’t want to take any chances.

Black Gold

One of the most aggravating features, weirdly, turned out to be the automatic lid. Unlike the Mill, which uses a mechanical foot pedal, the Reencle has a sensor that wildly flings open the top at even the slightest hint of movement, much to the terror and dismay of my two cats. There’s a way to disable it and use the button on the lid, but given that one’s hands are usually full and/or dirty when needing to open the lid, this proved to be an even worse solution. For this reason I couldn’t put the Reencle on a countertop (the lid opening wouldn’t clear the upper cabinets anyway), and it ended up around the corner by the back door, where there was less traffic.

Overall, though, I've been quite happy with the Reencle and its output—I've since used the cured Reencle compost for multiple houseplants other than the ferns, and they're all doing great. I plan to keep using it for outside plants once the weather warms.

For larger households, there's also a new, larger Gravity model for $699, with a larger processing capacity (3.3 lbs.) and quieter operation by 4 decibels. But even $499 isn't exactly dirt cheap (sorry), so the Reencle is also available to rent for $35 a month with no time commitment. My reclamation of three people's worth of kitchen scraps may not save the world, but turning trash into a usable finished product for both fun and education? I can dig it.