It found that in 2008 garden furniture accounted for 67 per cent of the market (£366m), followed by barbecue accessories with 18 per cent (£101m) and barbecue equipment with 15 per cent (£82m).
AMA Research said factors driving sales include: an interest in al fresco dining; a return to trading up; a wider range of products; and products bought during "the Ground Force years" wearing out.
Barbecues could see trading up, wider ranges and higher-spec products (particularly gas products), while chimineas could replace patio heaters in popularity.
Leisure & Outdoor Furniture Assocation (LOFA) secretary Richard Plowman said: "We had strong growth five years ago but the past three years have been static. This year has been four to five per cent up on last year, but it all depends on the weather."
Plowman said LOFA's Solex trade show was proving successful competition for Glee and Garden Expo.
He added that some "major brands" such as Alexander Rose, Kettler, Weber and Barlow Tyrie were likely only to show at Solex.
Predicted market value
2008 Market value was £549m (down four per cent from previous year)
2009 Forecasted market value £563m (growth of three per cent from previous year)
2010 Forecast £580m (growth of three per cent)
2011 Forecast £597m (growth of three per cent)
2012 Forecast £630m (growth of six per cent)
2013 Forecast £651m (growth of three per cent).