A high potash fertiliser for bumper crops of juicy tomatoes npk 45 4 59 can be used on tomatoes grown outdoors indoors under cover and in grow bags apply in the spring and throughout the growing season how to use mix with water and apply to individual plants according to the instructions on the pack feed tomatoes in grow bags weekly according to the pack instructions until the second truss has set then increase the application to twice weekly for outdoor tomatoes apply the feed every 14 days per