Indoor Composting Guide

If you are just joining us, we have talked about WHY composting is a good idea, some BACKGROUND on it, as well as some GENERAL GUIDELINES. Now it’s time to stop talking about composting and start doing it, beginning with our basic indoor composting guide.

photo credit: Tim Musson via photopin cc

Indoor Composting Guide

Indoor composting requires a little more attention than an outdoor pile, but properly managed, it should have no smell and not attract pests such as rodents. As many have observed before, the worms in a compost bin are the quietest, least demanding pets you will ever have.

The first thing to talk about is the bin you will use, unless you are willing to have a pile of dirt and food scraps in the corner of the living room. There are a number of premade compost bins you can buy, but they are also very easy to make yourself, which gives you the flexibility of building one exactly the size you want. The size you pick depends entirely on how much compost you want to make. The size of your family factors into this, if you don’t generate enough scrap, you can’t feed a large bin – although having neighbors contribute is always a possibility. Once you’ve selected your bin, start by drilling quarter inch holes in the top and sides of it, at least ten in the top and each side. If you’d like, you can cover the holes with a fine mesh screen to make sure pests stay out.

Once you have your bin, you need to find a place to keep it, balancing convenience with needing to keep a temperature between 55 and 80 degrees F. If you decide to keep it outdoors, be sure to put it in a shady place to keep it cool in the summer and have a way to insulate it in the winter. You will also need a way to keep water from entering through drainage holes or you will wish you had fish instead of worms.

Now that you have the bin and it’s where you want it to be, it’s time to start composting. The first step is to add your bedding, typically shredded newspaper (but not full color or gloss paper as these have heavy metals in them that may end up in your finished compost) or cardboard torn into 1” chunks. Fill your bin about 2/3^rd full of bedding and moisten it. Remember that your bedding should be moist like a wrung out sponge, not dripping wet. Begin by adding your food scraps, keeping it disbursed evenly throughout the bedding material and also completely covered by the bedding.

The best worms for indoor composting are the species Eisenia fetida, the red wriggler worm. This is a very hardy worm that thrives in an indoor bin. In an established bin, each worm processes about ½ its body weight in food every day. You can get them from most garden supply stores or order them online. All you need to do to add them to your bin is simply pour them out on top of the bedding; they will move down and get to work.

As you add food, it’s best to add in different locations each time; this will give you an idea of how long different things take to break down. Remember to keep the scraps covered with bedding to keep it from developing a smell or attracting flies. As the bedding begins to resemble dark soil over a period of 3-6 months, it’s time to reap the rewards of the work of your silent helpers. The slow, easy way to do this is by moving your compost to one side of the bin and placing fresh bedding and food on the other side and allowing the worms to migrate over a month or so. A faster way is to lay a tarp out and place your compost in piles on the tarp. The worms will move to the center of the piles to avoid the light. While you wait for this, replace the bedding in your bin and carefully sort through the piles, separating worms from the compost and placing them back in the bin. If your plan is to use the compost in a garden, you also have the option of simply using the compost without removing the worms and buying new helpers when you set your bin up again. If you are going to use the compost in potted plants, it’s best to remove the worms.

In a perfect world, you will never have trouble with your bin, but in the real world it’s possible to make mistakes, especially if it’s your first attempt.

Here are some common problems and what to do to fix them:

• Odor – If you notice a smell from your bin, the likely causes are too much water, too much food, not enough oxygen or you are just added food with strong odors to your bin. Add fresh bedding to dry the bin out and be sure to mix the bedding regularly to keep it aerated. Some foods like onions and broccoli simply have a strong smell to them, if it bothers you, it’s best to avoid adding them.
• Fruit flies – if you get fruit flies in your bin, you can trap them with fly paper or a DIY fly trap. If you keep your scraps covered with bedding and avoid overfeeding you shouldn’t have a problem with flies, but if you do, you can either freeze or microwave fruit scraps before adding them to make sure all eggs are killed.
• Worm death – worms decompose quickly, it’s possible to end up with a bin with no worms in it pretty quickly. If your worms are dying, make sure that your bin is not too wet or dry. If the bedding and food is matting together your worms probably aren’t getting enough oxygen, turn the bedding more frequently. Remember that worms like the same temperature ranges as humans, but are less able to cope with extremes, temperatures outside the range of 55-80 will kill them pretty quickly.

There are a number of excellent guides to composting and indoor composting guides that go into more depth online, two that I have found helpful are from Mother Earth News and New York City’s guide to composting.