One of the things I love doing in my garden is using high color contrast in mass plantings to make a big impact. Black eyed susans, as shown in the above photo, is the one plant that provides that contrast I love and so easy to grow for my area. I love plants that tend to become invasive by spreading their seeds and pop up everywhere . . . I pull them up like weeds and relocate them to create a mass planting. I purchased seeds once and never had to make another purchase . . . my kind of plant.
Another way to provide high contrast in the garden is to utilize those plants with unusual leaves. One of my favorite plants to use for this purpose is shown in the above photo . . . Florida Beauties. Their leaves are white with green specks and look awesome again green foliage.
Crotons and aucubas are more favorite plants that provide a high contrast through foliage for my climate (zone 9).