The figures follow rises of five per cent in October and six per cent in November. The number of grow your own (GYO) gardeners plateaued in 2011 at 43 per cent.
Garden centre GYO sales were up 34 per cent. Top selling crops were tomatoes and herbs (20-25 per cent) and strawberries, apples and lettuce (15-20 per cent).
Potatoes, peppers, onions, raspberries, carrots and runner beans were grown by 10-15 per cent, with five to 10 per cent growing cucumbers, cabbage and blackcurrants.