Composted Pine Fines (Pine Wood Fines - OMRI)

Composted pine bark fines are a highly sought-after soil amendment and potting medium component, prized by horticulturists and gardeners for their ability to dramatically improve soil structure and health. This versatile material is the result of a carefully controlled aging process that transforms the small, shredded particles of pine bark into a stable, nutrient-rich, and beneficial organic product.


The journey begins with pine bark fines, which are the smaller, screened particles left over from the commercial processing of pine trees for lumber and mulch. These raw fines are then subjected to a period of composting, which can last for several months to over a year. During this crucial time, microbial activity breaks down the woody material, reducing its carbon-to-nitrogen ratio. This process is essential; using fresh, uncomposted bark fines can temporarily "rob" nitrogen from the soil as microbes consume it for their own decomposition efforts, potentially harming plant growth.

The resulting composted product is a dark, rich brown to nearly black material with a fine, uniform texture and a pleasant, earthy aroma. Unlike heavier composts, it remains relatively lightweight and does not compact easily. One of its most significant attributes is its naturally acidic pH, which makes it an ideal amendment for acid-loving plants such as azaleas, rhododendrons, camellias, blueberries, and hydrangeas.

Functionally, composted pine bark fines serve several key roles in the soil. Their porous structure creates excellent aeration, allowing vital oxygen to reach plant roots and preventing the waterlogged conditions that can lead to root rot. Simultaneously, they possess a remarkable ability to retain moisture, ensuring a more consistent water supply for plants and reducing the need for frequent watering.

As a soil amendment, incorporating composted pine bark fines improves the tilth and friability of heavy clay soils, making them easier to work. In sandy soils, they add much-needed substance and improve water and nutrient-holding capacity. Because the composting process has stabilized the material, it releases nutrients slowly over time, providing a gentle, sustained feeding for plants. It is widely used as a primary ingredient in high-quality potting mixes for containers and raised beds and as a top dressing or mulch that helps suppress weeds and regulate soil temperature.