Using Compost as a Heat Source
for Growing Seedlings on Hot Beds and in Greenhouses
Grow your own seedlings in winter using compost as your heat source! Learn how to use compost heating as a simple, reliable, and sustainable alternative to fossil fuels.
Compost is often called “gardeners’ gold” for the powerful benefits it brings to growing plants. But did you know that a compost pile can also be used as a “hot bed” while the materials are decomposing? We’ve been exploring the potential for making compost hot beds that serve as heated seedling beds during the winter, and we’ve now created a free written guide and video series to share our methods with other gardeners and market farmers.
A compost bin can reach 140 degrees or more inside the pile while it is in the hottest phase of decomposition. Some of that heat rises upward from the pile. By covering our hot beds with low tunnels made from hoops and plastic, we capture that heat before it escapes into the surrounding air. During the winter, we use these hot beds both in our greenhouse and outside under low tunnels; our only heat sources are the sun and compost.
Building a hot bed requires time, knowledge and resources, but it’s not difficult. Hot beds, warmed by decomposing manure, were used by peasant farmers in China more than 2000 years ago, by the ancient Romans, by French farmers in the 1800s, and many other enterprising gardeners and farmers around the world.
Once a hot bed is built, it takes care of itself and keeps emanating heat 24/7 quietly, safely and reliably for months. We hope that our written guide and vixdeos will help you to take advantage of this free and sustainable heat source at your own garden or farm.