"Garden furniture, barbecues and picnicware were strong, particularly in the last week of the month. Outdoor lighting and air conditioning did benefit from the hot weeks."
BRC director general Stephen Robertson said: "There’s no evidence here of any Olympic boost to retail sales overall. Sadly, apart from April - distorted by Easter timings - August saw the worst sales growth this year.
"Hot weather and the Olympics did help sales of party food and drink but that was more than offset by a really weak performance for non-food goods.
"It’s clear people were absorbed by the magnificent Olympics and had little interest in shopping, especially for major items.
"Usually-reliable online sales suffered, putting in the worst sales growth since we started the measure four years ago. Some retailers told us online activity was particularly thin in the evenings.
"If people weren’t watching television they were more likely to be following the sport on PCs and mobile devices than shopping.
"As summer gives way to the all-important Christmas run-up, retailers will be hoping sales that didn’t happen in August have been postponed and not lost entirely."
KPMG retail head Helen Dickinson said: "Retailers’ hopes that the Olympics would inspire a pickup in spending were dashed as shoppers stayed away from the high street and enjoyed the sporting spectacle from their armchairs.
"While, without doubt, the Olympics brought a much needed boost to consumer confidence, the country was ‘otherwise engaged’ in August and the sales figures show a mixed picture.
"Those areas of spending which are most discretionary suffered, with women’s clothing, furniture, flooring and home related items hit the hardest.
"However, it could have been much worse. August is traditionally a weak month for sales and it’s really the next three months that will have a critical impact on retailers’ profitability.
"The challenge remains to accurately forecast outcomes in such a volatile trading environment."
Garden Centre Association chairman Peter Burks said recent sales "were not too bad - down a smidgen on last weekend". He added that bulb sales had begun slowly.
Buckingham Nurseries assistant general manager and plant buyer Mike Easom said: "Trade is fair – nothing special. Indoor sales are good and plants are starting to pick up."
Horticulture Week figures analysis of garden centre turnover for the week from 27 August to 2 September was almost exactly the same as in the same week as 2011.
Outdoor plants were one per cent up, aquatics were four per cent down, books three per cent down, Christmas 30 per cent down, clothing and toys flat, craft 10 per cent down, food 10 per cent up, furniture eight per cent down, sundries flat, gifts four per cent up, houseplants flat, machinery 80 per cent up, pets flat and catering 10 per cent up.