Guide to Slow Composting

Slow composting is a more passive, low-maintenance approach to composting that relies on nature to break down organic materials over time. Compared to active composting methods that require frequent turning and moisture monitoring, slow composting lets nature take its course with minimal effort on your part.

What is Slow Composting?

Slow composting, also known as passive, cold, or cool composting, is the process of letting organic materials decompose and break down over months or even years with little to no effort. It occurs at lower temperatures compared to hot, active composting methods and involves simply collecting compostable materials in a pile or bin and letting nature take its course. The decomposition process happens more slowly due to the lack of aeration and the lower temperatures.

With slow composting, it can take 6 months to 2 years for your compost to fully mature depending on factors like the size and contents of your pile. While it requires patience, the hands-off approach and infrequent maintenance makes it an easy, beginner-friendly option for composting.

How Slow Composting Works

Slow composting relies on mesophilic bacteria and fungi to break down organic materials. Without active aeration and heat generated by frequent turning, the decomposition happens more slowly at ambient temperatures.

The initial mesophilic stage still produces some heat, slowly increasing the internal temperature of the pile. But the temperatures typically only reach 90-110°F compared to 130-170°F in hot composting. This more moderate environment allows different microbes and fungi to thrive and slowly chip away at the scraps.

Over time, the materials will gradually break down, shrink in size, and turn into finished compost. A well-maintained slow compost pile can produce usable compost in as little as 6 months, while a very hands-off pile may take up to 2 years. The less you turn and actively manage it, the longer the process.

The Pros and Cons of Slow Composting

Compared to other composting methods, slow composting has its advantages and disadvantages:


  • Requires very little maintenance or effort after initial setup
  • Lower risk of odor, pests, or overheating since temperatures stay moderate
  • Can compost year-round even in cold weather
  • Beginner-friendly due to hands-off process


  • Very slow process can take over a year
  • Doesn’t kill weed seeds or pathogens due to lower heat
  • Increased risk of odors, flies, and pests without proper care
  • Can be prone to becoming too wet, dry, or compacted without turning
  • Yields less finished compost than hot composting

The minimal effort required makes slow composting a good option for beginners or those without much time to actively manage a hot compost pile. But the lengthy process means you get finished compost much less quickly.

Getting Started with Slow Composting

Slow composting simply requires collecting compostable materials and letting nature take over. Follow these tips to get started:

1. Choose a Composting Method

Slow composting works with several methods:

  • Compost piles: Piling up compost in a freestanding heap is low-maintenance. Turn occasionally.
  • Bins or enclosures: Containing compost in a structure keeps things tidy but retains moisture and odors. Turning recommended.
  • Trench/pit composting: Burying kitchen scraps under 8-12 inches of soil is very low-effort but can attract pests.
  • Vermicomposting: Composting with worms speeds decomposition. Maintain proper moisture for worms.

2. Pick a Spot

Find a level, well-draining spot, away from plants and water sources. Part to full sun is ideal. Build up sides if needed to contain compost.

3. Add Brown and Green Materials

Mix coarse “browns” like wood chips, dried leaves, straw with nitrogen-rich “greens” like food scraps, grass clippings. Ideal ratio is 2:1 browns to greens.

4. Maintain Proper Moisture

Moisture content of 40-60% is ideal. Compost should feel damp but not soggy. Turn pile occasionally if too wet or dry.

5. Let Nature Take Over

Sit back and let microorganisms decompose the waste naturally. Expect finished compost in 6 months to 2 years.

Maintaining a Slow Compost Pile

While slow composting doesn’t require much work, some occasional maintenance improves results:

  • Turn or mix: Aerating every few months speeds decomposition, especially if pile is too wet, dry, or compacted.
  • Add browns or greens: Balance moisture and nutrients by adding carbon or nitrogen sources as needed.
  • Check moisture: Use a moisture meter or squeeze test. Dampen dry piles with water or add browns to soggy piles.
  • Monitor temperature: Probe the pile to ensure it stays under 120°F.
  • Control pests: Limit meat, oils, and pet waste. Cover pile with browns if flies or odors occur.

Troubleshooting Common Problems

Slow composting piles can run into issues if not occasionally maintained. Here are some common problems and how to fix them:

Pile Doesn’t Heat Up

  • Cause: Lack of nitrogen, moisture, or air.
  • Fix: Mix in fresh greens, turn pile, or add water.

Pile is Too Wet

  • Cause: Excess rain or too many wet greens.
  • Fix: Turn pile and add absorbent browns like wood chips or straw.

Pile is Too Dry

  • Cause: Lack of moisture or too many browns.
  • Fix: Water thoroughly or mix in fresh greens like grass clippings.

Odors from Pile

  • Cause: Excess nitrogen, moisture, or poor aeration.
  • Fix: Turn pile, add browns, or cover with layer of finished compost.

Slow Decomposition

  • Cause: Lack of nitrogen, moisture, or air. Cold weather.
  • Fix: Mix in greens, turn/aerate pile, or add compost starter. Insulate or cover pile.

Uses for Finished Slow Compost

The resulting finished compost will be a dark, crumbly, soil-like material. It can be used:

  • As a natural fertilizer – Mix into garden beds or potting soil to provide nutrients for plants.
  • For soil improvement – Adds beneficial organic matter to improve any soil’s structure and water retention.
  • For erosion control – Spread compost as a mulch on slopes or bare areas to prevent erosion.
  • To increase beneficial microbes – Introduces helpful microorganisms that enrich the soil ecosystem.
  • As a seed starter – Amend seed starting mixes to provide nutrients for germinating seeds.
  • For container gardens – Mix into potting soil for planters and houseplants to increase fertility.

Slow compost retains more beneficial microorganisms compared to hot composting methods. The stable organic matter acts as a slow-release fertilizer to help establish and feed plants.

Troubleshooting Mature Compost Issues

Finished compost from a slow pile is ready to use once it has a crumbly, dirt-like texture and earthy smell. But occasionally it may have some lingering issues:

Immature Compost

  • Cause: Hasn’t fully broken down yet, contains large undecomposed pieces.
  • Fix: Let it cure for longer, up to 2 years total. Or sift out large pieces to use remainder.

Slimy or Soggy Compost

  • Cause: Too wet, contained excess greens, lacked airflow.
  • Fix: Add absorbent browns, stir to dry out, use drainage layer in next pile.

Moldy Compost

  • Cause: Excess moisture.
  • Fix: Let it dry out fully. Don’t use on seedlings if moldy.

Stinky Compost

  • Cause: Anaerobic conditions or excess nitrogen.
  • Fix: Don’t use until smell dissipates. Improve aeration in next pile.

Alternative Slow Composting Methods

Beyond standard compost piles, some unique slow composting methods include:

Trench Composting

Bury kitchen scraps in shallow trenches in the garden and cover with 8-12 inches of soil. Plant on top for added nutrients as it composts underground.

Winter Composting

Continue adding materials to an outdoor pile all winter. Insulate with straw or leaves to retain heat. Finished compost ready by spring.


Composting with worms speeds breakdown in a contained bin. Maintain moisture and add bedding as worms consume waste.

Bokashi Composting

Ferment food scraps anaerobically using Bokashi bran to partially break down waste before burying or composting.

Sheet Composting

Cover garden beds with compost materials like manure and leaves to compost in place. Till into soil once broken down.

Slow Tumbler Composting

Add waste to a tumbling bin and turn occasionally for aeration. Slower than active tumbling but easier than unturned piles.

FAQs About Slow Composting

How long does slow composting take?

Slow composting can take anywhere from 6 months to 2 years depending on pile size, contents, and maintenance. Small, well-maintained piles may finish in 6 months. Very hands-off piles can take up to 2 years.

Does slow composting kill seeds?

Slow compost piles don’t get hot enough (over 130°F) to kill weed seeds and pathogens. Avoid composting weedy plants if this is a concern. Hot composting is better for weed management.

Can you turn a slow compost pile?

Yes, occasionally turning slow compost piles speeds decomposition and reduces odor issues. But it isn’t required for slow composting. Turn 1-3 times per year as desired.

Does slow composting smell bad?

Slow piles can develop odors if too wet. Prevent smells by maintaining airflow via occasional turning, avoiding excessive nitrogen, and covering food scraps with browns.

Is vermicomposting considered slow composting?

Vermicomposting uses worms to speed breakdown so it composts faster than other passive methods. But it still produces compost slower than active hot composting.

The Bottom Line

Slow, passive composting provides an extremely low-maintenance way to convert kitchen and yard waste into a valuable soil amendment using natural processes. While patience is required, the hands-off method makes it an easy entry point for beginner composters. With minimal upkeep, nature will take its course and produce finished compost over time that can enrich garden beds, houseplants, and more. Slow composting works as an earth-friendly system to recycle organic materials and cultivate fertile, living soil.