Sales of seeds and bulbs also did well in January at 12.5 per cent up.
Overall sales were about 5-7 per cent up. Clothing has done well at 10.26 per cent compared to 2014, plants are static, seeds and bulbs and sundries are showing "healthy increases".
GCA chairman Will Armitage said: "Throughout the winter months it’s important for people to keep bird feeders topped up.
"Birds require high energy, high fat foods during the cold winter weather to maintain their fat reserves so they can survive frosty nights and our BoT results show that kind-hearted people are certainly willing to help out their feathered friends by providing food for them. Healthy garden birds also help keep pest numbers down in the summer months, so it’s important to look after them."
Henry Street Garden Centre partner Alan Goold said: "Overall January sales are up with bird food leading the way due mainly to a drop in prices of the raw materials being passed onto the consumer.
"We also managed to sell through a lot of Christmas goods in a New Year sale, which enabled us to get out some new stock for spring and customers seem to be itching to see the new ranges of furniture coming out which are due to land in February so it does look as though people are more confident for the coming season."
Bents Garden & Home chief executive Matthew Bent said: "January is traditionally a quiet time in the garden centre and retail industry. Christmas is over and it’s still a bit too cold to be out in the garden or getting ready for the season ahead, so it’s important to focus on other product areas to encourage customers to keep visiting.
"Sundries have been good for us, but one of the reasons for our recent expansion is to be able to offer more products and experiences that aren’t seasonally focused. Our food hall, craft shop, cook shop and pet department are all new additions and are already proving beneficial as demonstrated by our January sales figures."
Creative Gardens, which has centres in Donaghadee, Bushmills and at Galgorm Castle, saw good sales throughout January.
Finance and marketing director Philip Gass said: "January trading was exceptionally good across all centres, like for like our Donaghadee and Bushmills centres saw increases of 23 per cent and 36 per cent, café sales continue to be strong but the significant increases in the garden centres are have arisen from a conscious effort to promote value and take advantage of the post-Christmas sale mentality.
"Traditionally sales in the first week of January have come largely from discounted Christmas goods, this year we expanded the scope of our sale offer significantly and encouraged a greater spend across all departments, even outdoorplants."
Another garden centre that saw good sales through January was Haskins Ferndown.
General manager Matt Hill said: "Footfall remained strong during January. Our post-Christmas shoppers focused on bird care and garden lighting within sundries and we enjoyed strong sales in clothing and gifts. The restaurant catering team also benefited from the influx coming in from the cold and wet."
St Peter’s Garden Centre manager William Blake said: "Our clothing department has been performing exceptionally well over the past 12 months, with full year sales up 64 per cent. We took the decision to introduce more ‘fashionable’ brands to the department and it has definitely paid off. In addition, we actively purchase ‘star buys’ for women and men for each month, which sell very well. These are normally well recognised leading brands, at promotional prices e.g. up to 50 per cent off.
"A good percentage of our clothing sales come from impulse purchases, and therefore items priced below £20, £30 and £40 work particularly well.
"January 2015 sales were 25% up, although a great deal of this will be clearance and end of season. January clothing sales have also benefitted from the colder weather."