Three recent studies from Dr. Jeb S. Fields’ Environmental Nursery Production Lab show that growers can reduce peat use in plant production by layering different substrate materials—a practice called substrate stratification—while maintaining plant growth or quality.

In the first study, the researchers tested how incorporating wood fiber into the bottom layers of containers affects plant growth. They found that using coarse wood fiber underneath and a finer moisture-retaining material on top helped the roots develop well, keeping the seedlings healthy and vigorous. The approach also offers growers the flexibility to tailor substrate mixes to specific crops or growing conditions.

A supporting study confirmed that layering low-peat and high-peat materials in the same container can significantly reduce overall peat use. Plants grown in these stratified mixtures performed as well or better than those grown in traditional uniform substrates.

A third study reinforces these findings, showing that stratified systems can cut total peat use while maintaining or improving plant quality compared to traditional uniform mixes.

Together, these findings give growers practical tools to reduce peat use, manage costs and achieve more sustainable production, all while maintaining the high-quality plants that customers expect.

Collectively, these findings provide practical strategies for nurseries and nurseries seeking to sustainably produce high-quality plants. By combining layered substrates, careful packaging and peat alternatives, growers can reduce peat dependence, improve root architecture and improve production efficiency.

These studies represent a step forward in sustainable gardening, demonstrating that environmentally responsible substrate management can go hand in hand with the production of high yielding plants.

According to Dr. Fields, “Researchers around the world have been looking for alternatives to peat for decades, but the answer may lie in managing the way we use the substrate we have. Through stratification, we can effectively reduce peat use by 50% without sacrificing plant growth or quality. Substrate stratification also allows the use of low-cost or recycled materials in place of permanent media and other sustainable growth materials and sustainable growth. Horticulture industry”.

The full article can be read on the ASHS HortTech e-journal website https://doi.org/10.21273/HORTTECH05570-24; https://doi.org/10.21273/HORTTECH05660-25; and https://doi.org/10.21273/HORTTECH05683-25

For more information:
American Society for Horticultural Science (ASHS)
ashlars.org