Diagnosing common backyard compost problems

compost pile

Home composting isn't very complicated, but you may run into one or more of these common composting challenges.

Check for moisture

One of the most common reasons a backyard compost pile works slowly or even stops composting is lack of moisture. The easiest way to check for proper moisture conditions in your compost bin is to randomly grab a handful of composting materials from the pile or bin. Make a fist with your hand and squeeze. One of three things will happen:

  • Water running between your fingers? The material is too moist, and you need to turn the pile until it dries out.
  • Beads of moisture form between your fingers: The moisture level is just right.
  • No moisture between your fingers? You need to add water.

Mix the pile well and repeat the fist test as necessary. Don't use this test if your feedstock is manure or contains food scraps.

The pile doesn't heat up

Size matters. In order to get the compost pile hot, it must be a minimum of 3’ high by 3’ in circumference. In the winter, it should be a minimum of 5’ x 5’.

  • Moisture. Try the fist test: Pick up a handful of compostable material, make a fist and squeeze it in your hand. If you do not see beads of water between your fingers, the pile is too dry. Turn the pile and water thoroughly with a hose. You should let the pile rest for several hours, then give it the fist test again. If beads of water do not form between your fingers, you need more water.
  • Nitrogen. If the pile is new, you may need to add more "green" to your pile. Try grass clippings or fruit and vegetable scraps. In a pinch, use a scoop of nitrogen-rich plant fertilizer.
  • Aerate. A compost pile needs to breathe to function efficiently. Use coarse materials such as wood chips to create air spaces in the pile and add carbon to the mix.
  • Maybe it's done. Compost is finished when it looks brown and crumbly. Use a screen to sift off bigger pieces. Use the finished compost in your garden or lawn.

There's an odor

  • Rotten egg smell. Your pile may not be getting enough air because it's too wet. Turn the pile with a shovel or pitchfork to let in air and mix things up. If particle size is small (under one inch), add a bulking agent such as wood chips.
  • Ammonia odors often indicate too much nitrogen such as grass clippings or food waste. Add more carbon materials — dead leaves, non-recyclable paper, or straw. Mix the pile thoroughly and see it passes the squeeze test for moisture.

Attracts rodents or other animals

  • Do not add materials such as meats, oils, fat, foods cooked in oils or fats, bones, dairy, and weeds that have gone to seed to the compost pile.
  • Keep it covered. Keep new food wastes covered with materials high in carbon and in the middle of the pile. Covering the bin will help keep out larger pests.
  • Insects such as gnats, millipedes, bees, and ants are a normal part of composting, but an active pile will create enough heat to kill their eggs and reduce the nuisance insects.