Filler material – Forthright Magazine
▻http://forthright.net/2019/05/12/filler-material
The classic method for creating a garden planter is to use three elements; a “thriller” (something eye-catching), a “spiller” (something to trail gracefully out of the container, and a “filler” (taking up space among the other two types of plants, and filling the gaps.) That filler plant fills up space while the other two elements get all the attention, even though they may be a smaller part of the composite arrangement.