Six datasets regarding our study on methane emissions of ditches of boreal forestry-drained peatlands of Finland: Dataset 1: Accepted methane fluxes analysed via manual chamber technique from ditches of 21 boreal forestry-drained peatland study areas located in Finland. Dataset 2: Temperature within ditches of 3 boreal forestry-drained peatlands (Ränskälänkorpi, Lettosuo and Paroninkorpi) studied in 2021. Dataset 3: Relative water table level (relative to the level in the beginning of June 2021) in ditches of 3 boreal forestry-drained peatlands (Ränskälänkorpi, Lettosuo and Paroninkorpi) studied in 2021. Dataset 4: Yearly methane emission factors calculated for different types of ditches in the study areas. Dataset 5: Tested random forest models' variables and their mean decrease in accuracy, and models' error rates in classifying boreal peatland forest ditches into moss-covered and moss-free categories. Dataset 6: Tested random forest models (as zipped .RData files) to classify boreal peatland forest ditches into moss-covered and moss-free categories.