Gallery: HOW TO: Use Naturemill’s Metro Composter to Compost Indoors Wi...

At-home composting is a growing trend we're pleased to see catching on, but if you're a city dweller with limited space -- or are adverse to curious odors and creepy crawlers -- traditional composters probably aren't ideal. But don't give up on the quest to turn your scraps into nutrient rich soil! There are several indoor alternatives out there, like NatureMill's Metro automatic composter. This powered unit uses a minimal amount of electricity to heat and churn food, turning leftovers into compost in just a few weeks. We recently got our hands on one of these beauties and took it for a test run - check out our step-by-step account of the process ahead, and see if this composter lives up to all the hype!

STEP 1: Getting set up

Remove all of the contents from the shipping box and find a good spot in your home to keep your unit. You will need to be close to an electric outlet, so a kitchen counter may work well. Shipped along with the NatureMill Metro is a box of wood pellets and a package of baking soda. These will be used later to help in balancing your compost mix. When you plug in your unit you will hear a faint humming sound and see the LED indicator on the front light up.

STEP 2: Figure out what you can and cannot compost

Read over the included list of products that you can and cannot use in the composter. A top tip is to think GREEN and BROWN for things that can be composted indoors. “Green” items would mean fruits and veggie scraps, egg shells, coffee grounds,and even meat, poultry, and fish. Examples of “Brown” items are breads, pasta, grain, straw, and wood shavings. Things to avoid large amounts of acidic fruits (like lemons), and veggies that will produce strong odors like kale, mustard greens, and cabbage. Also stay away from paper, fibrous items like corn husks (they could cause a jam) and really hard items like peach pits. Unfortunately, you also cannot put compostable plates or utensils into the NatureMill.

STEP 3: Warming up your machine

Open the lid of top chamber and load it half full – about 5 cups worth. Add one scoop of saw dust pellets and 1 tbsp of baking soda in with the mix. Close the lid give the NatureMill some time to work its magic. The interior will heat up, and in about an hour you will hear mixing and churning in the upper chamber. The mixing will continue to happen every hours.

Insider tip: It helps to cut up anything that is large, into small pieces; think banana peels, orange peels, broccoli bits, carrot chunks, etc. Banana peels, in particular, if they are long and uncut, can turn stringy and wrap around/clog the motor. The smaller the pieces, the easier they are for the composter to “digest” — you also have less chance of damaging the motor.

STEP 4: Add your scraps and let the machine work its magic

Continue to add Greens and Browns to the upper chamber, balancing the load with sawdust pellets and baking soda. In about 2-3 weeks press the “Transfer” button to dump composting food down to the lower chamber. To access the lower chamber, remove the panel on the front of the unit. This panel is made from Temperene, a recyclable material that resembles Styrofoam. Inside is a tray that can be pulled out, so that you can take your compost to your garden.

STEP 5: Remove your compost and feed your plants

About a week after the transfer, you can remove your compost and spread it in with your plants. During the week, the food will continue to compost while in the lower chamber.




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  1. endersmiths March 22, 2012 at 2:43 pm

    Thanks for the awesome review! It’s great to see that composting has come a long way since the start. Traditionally, composting was to pile organic materials until the next planting season, at which time the materials would have decayed enough to be ready for use in the soil. The advantage of this method is that little working time or effort is required from the composter and it fits in naturally with agricultural practices in temperate climates. Disadvantages (from the modern perspective) are that space is used for a whole year, some nutrients might be leached due to exposure to rainfall, and disease producing organisms and insects may not be adequately controlled.

    Composting was somewhat modernized beginning in the 1920s in Europe as a tool for organic farming. The first industrial station for the transformation of urban organic materials into compost was set up in Wels/Austria in the year 1921. The early personages most cited for propounding composting within farming are for the German-speaking world Rudolf Steiner, founder of a farming method called biodynamics, and Annie Francé-Harrar, who was appointed on behalf of the government in Mexico and supported the country 1950–1958 to set up a large humus organization in the fight against erosion and soil degradation. In the English-speaking world it was Sir Albert Howard who worked extensively in India on sustainable practices and Lady Eve Balfour who was a huge proponent of composting. Composting was imported to America by various followers of these early European movements in the form of persons such as J.I. Rodale (founder of Rodale Organic Gardening), E.E. Pfeiffer (who developed scientific practices in biodynamic farming), Paul Keene (founder of Walnut Acres in Pennsylvania), and Scott and Helen Nearing (who inspired the back-to-land movement of the 1960s). Coincidentally, some of these personages met briefly in India – all were quite influential in the U.S. from the 1960s into the 1980s.

    There are many modern proponents of rapid composting that attempt to correct some of the perceived problems associated with traditional, slow composting. Many advocate that compost can be made in 2 to 3 weeks.[3] Many such short processes involve a few changes to traditional methods, including smaller, more homogenized pieces in the compost, controlling carbon to nitrogen (CN) ratio at 30 to 1 or less, and monitoring the moisture level more carefully. However, none of these parameters differ significantly from early writings of Howard and Balfour, suggesting that in fact modern composting has not made significant advances over the traditional methods that take a few months to work. For this reason and others, many modern scientists who deal with carbon transformations are sceptical that there is a “super-charged” way to get nature to make compost rapidly.[1] In fact, both sides are right to some extent. The bacterial activity in rapid high heat methods breaks down the material to the extent that pathogens and seeds are destroyed, and the original feedstock is unrecognizable. At this stage, the compost can be used to prepare fields or other planting areas. However, most professionals recommend that the compost be given time to cure before using in a nursery for starting seeds or growing young plants. The curing time allows fungi to continue the decomposition process and eliminating phytotoxic substances.

    Some cities such as Seattle and San Francisco require food and yard waste to be sorted for composting.

  2. wimwen March 11, 2012 at 6:08 pm

    Good stuff. I do composting the old way and this machine looks much better. Montana, where I live, has a shorter than short growing season that’s more attuned to cultivating tundra than growing tomatoes. The season is so short that many experienced growers purchase products for indoor gardening, like grow lights, to get a jump on Mother Nature. I know a woman who tried for years to grow decent tasting tomatoes. They always turned out puny, mealy and well, not very good! In other words, tomatoes only their cultivator could love. Last year, she picked up some fertilizers and finally decided to mix some organic compost into her soil for a little extra umph. It worked so well that they grew big and beautiful and caught the attention of someone who actually stole the crop out of the woman’s back yard. The gal was so miffed she actually filed a police report about it!

  3. todd lamont March 7, 2012 at 9:50 pm

    Pretty awesome. I want one!

    I have seen one of the earlier versions at a friend’s how and it seems to work well.

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