The group said this role provides new opportunities to innovate and diversify the product range.
Whalley joined Blue Diamond as head of gardening in April 2014 from Wyevale Garden Centres.
He has undertaken and overseen range adjustments to align categories with the group’s target AB1 demographic. He has expanded the leisure portfolio with direct sourcing from manufacturers and "increased both the quality and quantity of own brand offering".
Blue Diamond managing director Alan Roper said: "Stuart has done excellent work in his role of head of gardening, demonstrating a clear affinity and awareness of sourcing quality products in line with the company ethos. This new role will significantly strengthen our approach to product development enabling us to provide innovative and exciting new products for our customers."
Whalley said: "My strength has always been in product development and I enjoy identifying products with great potential and applying my creativity to develop these products even further. By prioritising product, this gives us an amazing opportunity to offer a range that can outperform and differentiate us from our competitors."
Blue Diamond is now recruiting a replacement head of gardening with sole responsibility for the commercial management of the garden and leisure categories.