Overall sales were up 41 per cent for the month and are 20 per cent up for the year to date.
GCA chairman Will Armitage said: "The fine weather we have been experiencing has certainly had an impact on sales at our member centres as lots of gardeners get back out into their gardens.
"This is also the time of year when many of us will inspect our garden furniture or barbecue ready for the season ahead and realise that it needs replacing.
"I think the growing trend encouraging people to make more of their outdoor living spaces has helped to further boost sales in this area.
"Other good performers during the month were outdoor plants sales 123.80 per cent up, hard landscaping 114.39 per cent up, garden sundries 82.05 per cent up and seeds and bulbs 43.38 per cent up."
William Blake, manager at St Peters Garden Centre in Worcestershire, said: "We are really pleased with how our furniture and barbecue sales have performed during March.
"After a really difficult February, due to the impact of the flooding in the surrounding area, it is great to see people are confident enough to invest in high ticket value items. We spent a lot of time last year making sure we had good range of furniture for this year, based on both quality and value, and that hard work seems to be paying off.
"We have also made sure we are priced competitively against our competitors and have some really strong promotions to attract people in. Long may it, and this current weather, continue."
According to the British Retail Consortium, footfall in March was 1.8 per cent higher than a year ago, significantly up on the 2.9 per cent fall in February and above the three-month average of 0.4 per cent.