Why grower minimums?
Some growers may have a minimum number of bunches - that minimum depends on how the grower packages or boxes their flowers for shipment.
For example, if a grower packs 6 bunches of roses per box, then that would be the mininum number of roses you'd need to purchase from that grower. You can assort the colors/varieties in the box but they'd all have to come from that grower. If you wanted more than 6 bunches, then you'd have to fill another box with 6 more bunches.