Healthy fruit starts with healthy soil, and healthy soil starts with compost. At Frog Hollow Farm, compost is a cornerstone of how we care for our orchard. It is organic material that has been biologically broken down into a stable, living soil amendment that builds fertility from the ground up.

Our compost is made from organic materials generated on our farm and collected from local partners. Carbon-rich inputs include tree prunings, cardboard from packing facilities, and fruit waste from our farm kitchen, balanced with nitrogen-rich materials like used coffee grounds from Blue Bottle Coffee and horse bedding from nearby ranchers. By maintaining a roughly 70% carbon to 30% nitrogen ratio, we create a fungally dominant compost well-suited to perennial orchard systems.

Each year, we produce more than 5,000 tons of compost, transforming organic “waste” into a living resource that feeds our trees, strengthens our soil, and supports a more resilient farm ecosystem. At the center of this transformation is one powerful piece of equipment: our compost turner.

Meet the Compost Turner

Transforming large volumes of organic material into high-quality compost requires more than time; it requires thoughtful engineering. Our compost turner is a heavy-duty machine pulled by a 100-horsepower tractor, designed to move, mix, and aerate massive compost piles with precision.

At its core is a rotating steel drum fitted with evenly spaced blades. As the turner moves through the pile at about three miles per hour, these blades lift, toss, and break apart the material, reducing particle size and thoroughly mixing the pile. The blade shape is designed to drop the compost back into a uniform, pyramid-shaped windrow, ensuring even airflow throughout.

“The compost turner is really a marvel of engineering,” says Farmer Al.

Feeding Microbial Life With Air and Water

Compost is driven by microbes, and microbes need oxygen and moisture to thrive. The compost turner delivers oxygen through regular turning and is paired with a water tank that evenly moistens the pile as it’s mixed. This uniform distribution of air and water creates ideal conditions for microbial life to flourish and speeds up the composting process.

We typically turn each pile about six times over a three-month period. In that time, materials once considered “waste” are transformed into dark, uniform compost that is rich in microbial life and nutrients.

Why Compost Matters in Our Orchard

Compost is how we build long-term health in our orchard from the ground up. By improving soil structure and increasing water-holding capacity, compost helps our trees stay resilient during dry periods while supporting carbon sequestration in the soil. Its greatest value, however, lies in biology.

All the minerals present in our compost inputs remain in the finished material, transformed by microbes into forms that tree roots can readily absorb. When compost is applied to the soil surface, irrigation and rainfall move those microbes and nutrients into the top six inches of soil, where most feeder roots are active. There, microbial life works in direct partnership with tree roots, delivering nutrients as needed and strengthening trees’ natural defenses.

This biologically driven system enhances nutrient cycling, improves water uptake, increases disease resistance, and helps trees withstand weather extremes. The result is healthier orchards and more flavorful, nutrient-dense fruit for everyone to enjoy!