We have 12 different dahlia companion plants for you to consider ... you can select an ornamental grass like fountain grass (Pennisetum alopecuroides) to plant behind the dahlias in your garden.

In USDA Zones 10–11, plant plumeria outside ... Purple fountain grass (Pennisetum setaceum ‘Rubrum’) thrives in hot, sunny spots, making it a good companion for plumeria.