A long-term trial was conducted in the coconut plantation at Thrissur, Kerala, India from July 2008 to June 2013. Time series analysis was performed with monthly weed count data to determine seasonality of selected weeds of a coconut garden. A multiplicative model was assumed for the time series and the seasonal index was worked out for each weed species. The results revealed that Axonopus compressus, Biophytum sensitivum and Mimosa pudica dominated during the South West monsoon season while Curculigo orchioides and Desmodium gangeticum were seen germinating during the North East monsoon period from September– October and were predominant in the field till February. Hemidesmus indicus and M. pudica were the weed species seen throughout the year. However, their predominance was the field was between November to April and July to November, respectively.