Apparatus for treating grass comprising a grass treatment unit 200 configured to be affixed to a grass treatment machine; a cassette 206, the cassette 206 comprising a grass treatment device 207 configured to rotate in response to a rotation of a drive shaft, the drive shaft being connected to a motor located at the grass treatment machine, the grass treatment unit 200 comprising means 211 to releasably mount the cassette 206 on the grass treatment unit 200, wherein the grass treatment device 207 is selected from a set of grass treatment devices, the set including a vibration drum.