From PinataIsland.info, the Viva Piñata wiki
How best to grow it
Must be planted in mud.
Use 3 applications of brown fertilizer immediately after planting it, for maximum effect.
Bullrush seed uses
- 12 bullrush in the garden helps meet the Dragumfly Resident requirements.
- 14 bullrush in the garden helps meet the Chippopatamus Visit requirements.
- Eating 2 bullrush helps meet the Pigxie Romance requirements.
- Eating 3 bullrush helps meet the Sweetooth Romance requirements.
- Eating 10 bullrush helps meet the Chippopatamus Resident requirements.
- Feeding a bullrush to a White Flutterscotch changes its color to a brown variant.