Scotts Miracle Gro general manager Sheila Hill said: "It's purely down to a restructure which we felt was important for the UK business in order to drive efficiencies.
"We mirror the organisation of our parent company in the US having a brand leader at the forefront of the business being more reactive to the consumer, rather than having an additional layer.
"Paula left on very amicable terms and we wish her the best of luck with her new consultancy service."
Hill said Glee was the "best ever" and Scotts is in a "great place for next year to drive growth and market share".
"We're in a great place with the core business and with our new birdcare category. The re-launch of Chapelwood was well received and we have won quite a lot of new business and held onto the accounts we had."
She said new product Groables was in production and had received "amazing feedback" as a piece of "true innovation" for all gardeners.