Some garden retailers are "losing the plot" by turning their businesses into "food halls", Root One Garden Centre owner Jeremy Brudenell has claimed.
The Oxfordshire garden centre has secured planning consent from South Oxfordshire District Council for extensions.
There will be 500sq m of new build for the family-run centre and Brudenell plans a triple-span polytunnel to extend plant sales.
"Plants are selling more and we need to accommodate more," he said.
Destination garden centres that have shifted their focus away from general gardening sales to food-related sales should "just call themselves a food hall, not a garden centre", said Brudenell.
The cafe at Brudenell's Root One Garden Centre now accounts for 20 per cent of the business but "plants are the stars and the feed-back we get from our customers is that the other guys have lost the plot and we're picking up their business", Brudenell explained.
He added: "We're 18 per cent up on 2013 and we've had record years every year, apart from three years ago. We stick to the basics and care about what we do, and that has struck a chord with our customers."
Diversification - 'Neglect gardening offer at your peril,' says Roper
Blue Diamond managing director Alan Roper said: "If as an operator you can protect and continually strengthen your gardening offer while embracing the opportunities of restaurants and non-gardening, you have a strong future. Neglect the gardening offer at your peril."
Retail consultant Neville Stein added: "The challenge is to try and grow the gardening category rather than let sales slip. It's understandable that garden centres have diversified into new categories as it seemed hard to grow plant sales in recent years."
Garden Centre Association chief executive Will Armitage said he hopes gardening sales will take centre stage in 2015, but he warned that if the weather is bad next year "we will fall back on other elements".