If you’ve committed your household to composting, you’re on the right track to living more sustainably and lightening your footprint. There are many different compost methods: While industrial composting can turn just about any material into soil conditioner, the composting taking place in your backyard bin doesn’t get as hot.
In general, the average home compost pile is turned once every couple of weeks (or months!) and usually reaches high temperatures between 150 and 160 degrees F. While a long list of materials will break down nicely in these conditions, there are still a few items that probably don’t belong in the average home compost pile. Keep these away from your bin to ensure your final compost is safe to use in the garden and won’t burden your neighbors with obnoxious odors.
1. Diseased or Treated Plants
If you notice that a plant in your garden is showing the signs of viral or bacterial infection (think tobacco mosaic virus on tomatoes or soft rot on potatoes and onions), don’t add it to the compost pile. The same goes for any plants treated with non-organic pesticides. Your compost pile isn’t hot enough to kill diseases or burn off pesticides, so using compost with these inputs can potentially spread them to future gardens.
2. Meat and Other Animal Products
Meat, bones and animal fats should be left out of the home compost pile. These items are known to attract unwanted pests (like raccoons and rats), and the bacteria that break down meat and other animal products are not commonly found in the compost pile. As a result, these items tend to break down more slowly and cause unpleasant odors. Instead of letting these products go to waste, though, consider leftover bones and meat to make a stock for soups.
3. Dairy Products
Similar to meat, dairy products are known to attract unwanted pests. Unlike meat, however, dairy products tend to decompose rather quickly, and unless a pile has a large amount of brown (carbon-rich) inputs to balance this quick decomposition, adding dairy can affect the overall health of the pile.
4. Pernicious and Overly Seedy Weeds
Pernicious weeds are a category of weeds that can survive the temperatures in the compost pile and can regrow from pieces of root rather than seed; these are also the weeds that can harm to desired crops, like vegetables and flowers. They include nut sedge, bindweed, Bermuda grass, dandelions, yellow dock and burdock, but will vary by area. Both pernicious weeds and weeds that have gone to seed should not be added directly to the compost pile. An alternative is to place them in a black plastic bag for about one season before adding to the pile; this will effectively kill any growing potential left in the plant material.
5. Coated Paper
While most unwanted paper, once shredded, is an excellent addition to the compost pile, it’s best to avoid adding coated paper, including newsprint, magazines and some junk mail. These papers might or might not have a glossy sheen and should go into the recycling bin instead.
6. Cooking Oils
Both animal and plant-based cooking oils, especially in large quantities, should be left out of the compost pile. These items will attract unwanted pests and have the potential to negatively affect the moisture content of the pile.
7. Manure from Meat-Eaters
While manure from chickens and herbivores like sheep, rabbits and goats can be helpful in a compost pile, manure from animals that eat meat (including cats, dogs and humans) should not be added. The bacteria and potential pathogens in this type of manure can be harmful to humans. When using manure from plant-eaters, it’s still important to balance out the pile with a lot of carbon-rich inputs because manure tends to be very high in nitrogen. Also, horse manure often contains seeds that have not broken down in the digestion process, therefore could contribute to a weed problem in your garden.
Sawdust can be a valuable carbon-rich input, but unless you know that the sawdust came from untreated lumber, avoid putting it in your bin.