How to Reduce Peat Use in Container Production with Layering
The floriculture industry is constantly looking for ways to improve sustainability, and one hot topic is reducing the use of peat moss. Thanks to recent American Floral Endowment-funded research from Dr. Jeb Fields and his team at the University of Florida, growers will soon have an easier, more affordable way to reduce peat use without compromising plant quality: substrate stratification, particularly with the use of wood fiber.
What is Substrate Stratification?
With stratification, you can think of the pot as a layer cake. Stratification means using different potting media in layers, typically with different media on the top and on the bottom. In this research, the top layer remains peat-based, retaining its excellent growing properties, but the bottom layer uses cheaper, more sustainable materials like wood fiber or pine bark.
This approach can reduce peat use by up to 50%, while still producing a saleable crop. Not only is this alone a great option for growers seeking to reduce their bottom line, but stratification allows growers to transfer those saved dollars to further optimization of the high-performance substrate in the upper layer.
Why Wood Fiber?
Researchers found that using pine bark or wood fiber as the lower layer of the substrate helps support strong root growth, with the wood fiber outperforming traditional pine bark in some instances.
What’s more, they explored the idea of a “filler strata” — using low-cost or locally available waste materials in the bottom layer. This opens the door to using on-site or regional waste products, helping growers save money, reduce waste, and reduce their carbon footprint.
Key Findings after Year 1
- Stratification works best when the lower layer is less than 50% of the container volume. Going over that can make the system less effective. But keeping the bottom layer at about 25–40% can improve resource efficiency and plant rooting.
- Wood fiber substrates performed just as well, or better, than traditional mixes in trials with crops like petunias.
- Coco coir-based top layers combined with wood fiber bottoms are showing promise as peat-free growing options.
These findings are especially useful for growers who want to experiment with stratification without completely overhauling their systems.
What’s Next for Fields’ Research?
Next year’s research will focus on optimizing the upper strata (the top layer) to work even better with these wood-based lower layers. Researchers also plan to test how these materials affect moisture levels and nutrient availability, using advanced tools like moisture sensors. “We are working with growers and the substrate industry to derive the best mixes for peat and perlite reduction in stratified systems,” says Jeb Fields, the leader of the stratified substrate movement.
Ultimately, the goal is to develop clear best practices and step-by-step guides that growers can follow, tailored to their crops and climate, to incorporate the use of more economically and environmentally friendly materials for the bottom strata.
Why This Research Into Substrate Stratification Matters
Even though there’s no immediate shortage of peat in North America, many growers (and their customers) are demanding more sustainable practices. This research is also catching global attention. A recent report from Wageningen University in the Netherlands cited U.S. stratification work as a foundation for their own efforts, showing that this homegrown innovation could soon become an international trend. With Europe facing historic peat shortages, the stratified substrate solution is sweeping the globe, and we have an inside seat to the innovations coming from AFE-funded research.
For additional information on research findings regarding substrate stratification and reducing peat use, please read the original article found on the American Floral Endowment website.
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