Hemp hurd fiber: a sustainable substitute for sphagnum peat moss in greenhouse and nursery plant production

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Commodities

• Vegetables: tomatoes
• Additional Plants: ornamentals

Practices

• Crop Production: greenhouses, nurseries
• Education and Training: demonstration, on-farm/ranch research

Sphagnum peat moss is an important component of greenhouse and nursery plant potting media, but mining of the material is unsustainable due to its negative environmental impacts. Several European countries have banned the sale of peat to consumers, and restrictions are likely to be extended to the horticultural industry. Restrictions on the sale of peat are expected to expand to Canada, which is the major supplier of peat to the United States. Hurd is a byproduct of all hemp growing operations (fiber, grain, medicinal) and is an untapped renewable material. Milled hurd is similar to peat in many characteristics (porosity and water-holding capacity) and can likely serve as a substitute in container media. The novel approach is to repurpose hemp hurd fiber as a substitute for peat moss in container growing media for the production of horticultural crops. Research is needed to ascertain the amount of hurd that may be substituted for peat, what crop groups may be grown using hurd, and the impact hurd will have on nutrient availability. Outdoor nursery and indoor greenhouse production studies will be conducted to evaluate if hemp hurd can be used to fully or partially (33% or 66%) replace peat in growing media for crops of woody plants (evergreen and deciduous), herbaceous perennials and ornamental grasses, bedding plants, and vegetables. The availability of nutrients in hurd substituted media compared to peat-based media will be evaluated. The horticultural industries recognize that regulation of peat is on the horizon and alternatives must be identified that make their crop production more sustainable. In a recent survey of southern New England growers, 100% responded that they were extremely or strongly interested in research evaluating sustainable alternatives to peat in growing media. All growers surveyed agreed that the use of hemp hurd, a renewable resource, for plant production would be viewed favorably by the public. As part of the process of fully evaluating hurd as an alternative to peat, a nursery producer will grow plants on farm using hurd substituted media. Growers will participate in annual on-site demonstration events where they will view the outdoor nursery and greenhouse trials, receive preliminary research results, and provide feedback on the project.  To reach a broader stakeholder audience, short educational videos that serve as “Reports from the Field” will be developed to highlight research activities and results and shared via UConn Extension, advisory committee member, and grower social media accounts.

Evaluate hemp hurd as a substitute for sphagnum peat moss in growing media for container production of horticultural crops. Knowledge will be acquired about what crop groups may be grown using hurd, the amounts of hurd that may be combined with traditional media components, and the impact hurd substitution has on the availability of nutrients. If it can be shown that hurd may be successfully substituted for peat during production of horticultural crops, then growers will seek to use this byproduct of the hemp industries.