Houseplants were up 13.93 per cent. Outdoor plants were up 9.09 per cent. Catering was up 10.38 per cent. Gifts were up 11.14 per cent.
GCA chief executive Iain Wylie said: "It's great to see non-traditional categories such as clothing and food halls/farm shops doing well during July."
Sally Cornelissen, director at Burleydam Garden Centre in Wirral, which recently received the award for best garden centre in the North West at the GCA's annual inspections, said: "This July has been exceptionally good. We were concerned that the poorer weather compared with 2014 would be a challenge but strong performances from hardy stock, garden sundries and furniture sales coupled with the expected increase in catering turnover has delivered pleasing results.
"There is a definite rise in consumer confidence as illustrated by increased interest in high ticket items. We hope that this confidence will ride out hints of a rise in inflation in the light of the increase in minimum wage in October."
Lauren Cocks, marketing manager at Coletta & Tyson Nurseries and Garden Centre in East Yorkshire, said: "We are seeing strong growth within our houseplant department, we have always struggled with strong competition from supermarket prices but it seems the tables are turning and customers are turning to garden centres to add colour and texture to their homes as well as their gardens.
"Catering is so important to our garden centre, people come just to visit our café now and it has meant we are no longer a garden centre with a café. To many we are a catering outlet in our own right. This means we have to keep improving our offering and keep it interesting for new and old customers alike."