Passive Composting

When speaking to gardeners about the benefits of composting, I often get a common piece of feedback: "Well, that sounds great, but I just don’t have the time.” And it’s true that while home composting has many benefits for both the home landscape and the environment, it does require some extended effort to do it successfully. In addition to correctly layering green and brown organic matter, periodic turning of compost is necessary to get air to the microorganisms. Frequent watering is also required for those microorganisms. Then there’s the matter of ensuring proper internal temperatures while mitigating the various issues that may arise.

The good news, however, is that composting doesn’t have to be this difficult. With a little more patience, gardeners can employ a method known as passive, rather than active, composting.

Passive composting is a straightforward process. It involves collecting the same materials used in active composting, a pile at least 3’ x 3’ in size: entirely dead brown carbon organic matter and green nitrogen-rich organic matter. These materials are layered in a designated area. However, many of the care aspects begin to diverge at this point. While turning and watering can help move a passive compost pile along in the decomposition process, passive composting by its nature relies on nature itself.

Where an active compost pile is managed with feeding and heating factors added, a passive compost pile is left to acquire those independently. This approach extends the timeline from a typical 3–6 month process to an 8–12 month process, with winter cooling periods contributing to slowing. However, the finished product of completed compost is ultimately the same, requiring much less effort.

These piles can be in a traditional compost bin, a covered hole in the ground (trench composting), or even a simple standing pile. However, you will want to keep some factors in mind to avoid troubleshooting later. As with active composting, keeping a consistent layer of dead brown carbon material (leaves, straw, shredded paper, etc.) on top of the pile will help keep odors down and deter flies and wildlife.

Likewise, monitoring the ingredients added to the pile will contribute to the overall success of decomposition. The vitality of the microorganisms present determines the ultimate success of the pile, and an overly acidic environment can disrupt their activity. Citrus peels, coffee grounds, pine needles, and other organic matter are compostable but may cause issues when introduced in large amounts. Balancing these with plenty more of those carbon-rich "browns" will then help mitigate this.
It should also be noted that while compost provides fertilizer-like benefits, the amount of nutrients supplied varies by the ingredients added, and it is not a reliable method for significantly altering specific soil nutrient levels.

Nevertheless, after observing the extended decomposition period, gardeners can still reap the benefits of humus-rich, completed compost. This compost can be worked into vegetable gardens, spread over ornamental beds, raked into lawns, or even used as mulch. A simple test to know if it’s complete? It will look and smell like soil, even if it technically isn’t. You’ve created compost – minimal effort and all.

by Anthony Reardon, Horticulture Small Farms Agent, 2025