Sometimes you may want to suppress weeds and or native plants between Vetiver hedgerows so one method available is reducing the lineal distance between rows to 1 metre or lower. This will shade between each row and hopefully slow down the undesirable plants.
If you have areas you’d rather not mow often and require mulch around your property, why not try planting Vetiver hedges for biomass? They can be cut 3-4 times a year in a wet Summer climate. Sometimes they can even become habitat and material for nests.