The Essential Composting Task You're Probably Not Doing Enough

Key Takeaways

Turning compost piles provides more air to beneficial microbes, helping to speed up the composting process and creating enough heat to kill weed seeds, pests, and pathogens.
Aim to turn a hot compost pile every 3–4 days to stay in the optimal temperature range to produce finished compost in 6 to 8 weeks.
Cold composting doesn't require turning, but it takes up to a year to complete the decomposition process and won't heat up enough to destroy weed seeds or pathogens.

If you pile up organic material in a remote corner of your garden, it will eventually turn into compost without you needing to do a thing. But if you want to create high-quality compost fast and make sure your compost doesn’t harbor weed seeds or plant pathogens, you’ll need regularly turn your compost pile. How often compost needs turning varies depending on several factors, so we’ve put together this simple guide to help you determine exactly when you should and shouldn’t turn compost.

Why Turn Compost?

Outdoor composting relies heavily on aerobic bacteria, fungi, and other beneficial microorganisms that thrive in an oxygen-rich environment. During the composting process, these microorganisms use up oxygen and generate heat, which is why the center of compost piles feels warm.

If you don’t turn your compost, these beneficial microbes will eventually deplete all of the oxygen in your compost pile and start to die. This causes the composting process to slow down and can result in soggy or smelly compost piles.

By turning compost, you introduce more oxygen into the center of your compost and create an ideal environment where beneficial microbes thrive. When given ideal conditions, microbes create compost faster and generate a lot of heat, which kills weed seeds as well as plant pests and pathogens.

If you’re still on the fence about turning compost or not, consider that aerated, hot compost piles create compost in about 6 to 8 weeks, while unturned, cold compost piles may take a year or more to produce finished compost.

How Often to Turn Compost

How much you’ll need to turn compost depends largely on whether you are doing hot composting or cold composting. Which method works best for you depends on your gardening goals and the time of the year. If you want to create a lot of compost quickly, hot composting is best. If you’re not concerned about when your compost will be ready to use, cold composting works just fine.

Hot Composting

Hot composting is the fastest but also the most involved form of composting because it requires the most turning. Temperatures that are too hot or too cold harm composting microorganisms and slow down the composting process. The target temperature range is between 104° and 160°F. To stay within that window, you’ll need to turn the compost about once every three to four days.

Investing in a compost thermometer will help you keep track of compost temperatures and let you know when your compost needs to be turned. Monitoring compost temperature is also critical if you want to ensure your compost is pest and weed-free. Compost piles need to stay above 131°F for 15 days in a row to kill off most plant pathogens or around 145°F for 30 consecutive days to kill tough weed seeds.

Cold Composting

Cold composting is a much more passive process than hot composting. The piles don’t need to be turned at all. It is a great option if you don’t want to worry about turning compost; however, turning cold compost piles from time to time helps them break down a little faster. Just keep in mind that without regular turning and temperature control, cold compost piles won't generate enough heat to kill off weed seeds, plant pathogens, and pests.

In winter, when temperatures are below freezing, do not turn your compost. Aerating compost can slow down the composting process and even cause piles to freeze over. If you live in a cold climate and want to continue composting in winter, try indoor composting methods such as bokashi composting instead.

Tips for Faster Composting

Turning compost is the best way to create compost fast. But these tips also speed up the composting process and even limit the number of times you need to turn compost piles.

Add air. If you want to turn compost a little less often, mix some bulky materials, such as loose straw or chopped leaf litter, into your compost. Another option is to insert a drilled PVC pipe into the center of your pile. This will introduce more air into your compost and reduce the amount of turning.
Invest in quality tools. The best way to turn compost piles is with a strong shovel or gardening fork.
Try 3-bin composting systems or compost tumblers. These composting systems make it much easier to turn compost. A compost tumbler also keeps out unwanted critters.
Mix nitrogen- and carbon-rich materials. Compost breaks down faster if you use a ratio of about 1 part nitrogen-rich ingredients, such as vegetable scraps, with 3 parts carbon-rich ingredients, including leaf litter, straw, or wood chips.
Add smaller ingredients. Cutting or breaking compost ingredients into small, 1-inch pieces before composting helps these materials break down faster.
Keep compost from drying out. Compost piles should be about as damp as a wrung-out sponge. Regularly sprinkle water over the compost pile.

Apply compost accelerators. If you have a bokashi compost bin, use the liquid as a compost accelerator and mix it into outdoor compost piles for faster composting. You can also purchase pre-made liquid or granular compost accelerators (also called compost starters).