Growing in loose mounds and reaching 8 to 18 inches tall, they can serve as annual ground covers, and are also attractive in hanging baskets or at the front of a border. Interspecific crosses are low-maintenance zinnias that have been introduced over the last decade. They combine the flower colors of garden zinnias with the durability of spreading zinnias. The Pinwheel series now includes flowers in gold, orange, pink on white, and white. They grow about 15 inches tall, covering the old flowers with new leaves and buds, and thus eliminating the need to deadhead.
Small zinnias make good edgers for summer annuals, filling in after spring pansies.
I particularly like 'Rose Border Beauty' with 'Purple Wave' petunias. Tall zinnias are ideal for cutting and can be planted in clusters between perennials in a sunny, mixed bed. Brick red Z. peruviana 'Bonita Red' is a good match for purple coneflowers. Where precise color coordination is important, look for seed packets with a single color of flowers. To find specific colors that best fit your planting scheme, you may have to scour catalogs for single colors of series such as Blue Point, Border Beauty, Oklahoma, Pinwheel, and Splendor.