Spanish Moss: Natural ColorDesigner Tip: When creating a floral arrangement using foam blocks, you should first cover the foam with moss. This is for 2 reasons! 1) It looks more natural and is aesthetically more pleasing than the look of foam. 2) You will actually use fewer floral stems to create your arrangement. Because the moss is textural, if you have a hole or space between flowers, you will see the moss and not the foam and will not feel the need to cram it full of more