14 Compost Safety Tips

Every gardener knows the benefits of compost. Compost improves soil texture and structure, boosts nutrients, and fosters a healthy biological community.

That said, compost is not completely devoid of risks. In particular, compost made with manure can contain harmful bacteria.

So how do we reap the benefits of compost while keeping pathogens from contaminating our fruits and vegetables? Here are some suggestions:

  1. Do not compost pet or human waste. Pet waste often contains pathogens that pose a serious threat to human health. Likewise, despite the current popularity of composting toilets in some circles, human waste requires special handling and preparation for safety, making it a poor choice for vegetable gardens.
  2. Do not compost manure from animals treated with medication of any kind. Not only is animal medication not likely to be great for your health, some medications could foster the propagation of resistant pathogens.
  3. Do not compost meats, dairy products, or fatty foods. At worst, these materials can introduce E. coli to your compost. At best, they tend to create a smelly mess that attracts raccoons, stray dogs, and other pests.
  4. Do not compost plant material treated with herbicides, pesticides, or other chemicals. These chemicals could come back to harm your plants, particularly if you use the cold composting method.
  5. Do not compost diseased plant material, noxious or invasive weeds, or weeds that have gone to seed. While the hot composting method can help eliminate some of these weeds and diseases, for entirely safe compost, it is best to avoid such ingredients altogether.
  6. Make sure fireplace ashes are completely extinguished. Warm embers can rekindle and ignite your pile. (Contrary to popular belief, hot compost made on the backyard scale is not otherwise susceptible to spontaneous combustion, particularly if kept moist. Such events are typically restricted to commercial-scale composting.)
  7. When composting livestock manure, use the hot composting method. The hot method will sterilize most harmful bacteria. To allow beneficial organisms to recolonize the compost, allow it to cure for one to two weeks prior to application.
  8. Wear gloves. Likewise, consider covering any open wounds with bandages before working with your compost.
  9. Wash your hands. When you are done building or turning a compost pile, wash your hands afterward. In particular, be sure to wash before eating food.
  10. Keep pets and children out of the compost pile. Pets and children young enough to put everything into their mouths have a strong attraction to unfinished compost, which could put them at risk for illness.
  11. Keep compost ingredients moist. Not only does a modest amount of moisture aid in the decomposition process, it will help prevent you from inhaling compost particles.
  12. Apply finished compost with different tools than those used for working with manure. For extra safety, use different tools for handling cold or unfinished compost than you use to apply finished hot compost.
  13. Wait 120 days after application to harvest foods if using the cold method. If you tilled the compost into the soil instead of applying it to the surface, you can reduce this wait period to 90 days. Properly made hot compost can eliminate the wait altogether. One caution—hot compost that failed to exceed 130°F for at least 15 days should be treated like cold compost.
  14. Take special precautions if you have a respiratory ailment or a compromised immune system. In these cases, you may want to forego the manure altogether. Likewise, avoid inhaling compost dust (if you can work inside a sealed tractor cab, that is ideal).

Safe composting is largely a matter of using safe ingredients. When in doubt, hot composting will also reduce pathogens, chemicals, and weed seeds, helping to ensure a quality result.

Helpful Resource

Composting Quick Start
More of our favorite composting resources.

Improving Your Garden Soil