Walker Environmental Group (WEG)

Grodan/Compost Growing


Walker Environmental Group (WEG)  works with various greenhouses to dispose of Rockwool (Grodan) that was used by growers for hydroponic production of vegetables and flowers. WEG wanted to investigate ways to repurpose the Rockwool and engaged with the Agriculture & Environmental Technologies Innovation Centre at Niagara College. In 2019, processed Grodan material was incorporated into leaf and yard waste compost production at different volume percentages by WEG, in order to assess its impact on the composting process, as well as the final compost product. WEG also wanted to determine if the processed Grodan material can act as a bulking agent in compost production.


WEG and Niagara College collaborated on a course-based project with student researchers from NC’s Greenhouse Technician program over two semesters, to test the quality of different finished Grodan/compost blends when compared to the control. The growing trial findings will give WEG a better understanding of the quality of Grodan/compost blends and will help to clarify the end use of these new compost blends – whether it is greenhouse/nursery potting mixes and/or Gro-Max/Gro-Turf types of mixes.

Update as of May 12, 2021:
Following previous “instrumental” growing trials conducted by student researchers from Niagara College’s Agriculture & Environmental Technologies Innovation Centre, Walker Environmental Group (WEG) is advancing its development of its rockwool growing media recycling program. The company has since received funding under the Greenhouse Competitiveness and Innovation Initiative from the Agriculture Adaptation Council to study the market development of rockwool recycling services. Walker is also working with the Ontario Greenhouse Growers Association to validate composting as a means for effectively destroying pathogens affecting greenhouse grown plants. “The work previously conducted at Niagara College has been instrumental in helping us develop this program as we work to find a suitable means for treating, recycling and creating valuable products from waste growing media,” said Greg Robles, manager, Innovation & Optimization Resource Recovery, Walker Industries.

Funding: Ontario Centres of Excellence (OCE) through their College Voucher for Technology Adoption (CVTA) program and the NC-led Greenhouse Technology Network (GTN).