Prized for their bright, bold, and extraordinarily diverse blooms, dahlias are impossible to ignore. Choose from fiery oranges and reds, cool whites, and pretty pinks to boost your beds, borders, and container displays from midsummer to late fall.
Comprising so many different forms, dahlias offer something for everyone. Those with a penchant for large, dramatic focal plants will be drawn to the giant-flowered types that exceed 10 inches (25 cm) in diameter. For more relaxed or informal designs, opt for the small or medium-sized blooms, and if you are planting pots, try the miniatures, which measure just 4 inches (10 cm). In addition dahlias are divided into ten main groups that reflect the size, shape, and structure of their flowerheads.
Most dahlias bloom from midsummer to the first frost, providing a long season of color and texture. There are tall types in each of the flower categories that make excellent back-of-the-border plants, with some reaching up to 5 feet (1.5 m) in height. By positioning them among other late-flowering grasses and perennials you can also disguise the stakes that are needed to support their stems.
For pots or the front of a border, choose the compact forms. Look for the label “dwarf bedder,” which describes plants that do not exceed 2 feet (60 cm) in height. The gallery dahlias, with flowers named after famous artists and art movements, such as D. ‘Art Deco’ and D. ‘Gallery Cézanne’, fall into this group. Remember, too, that many small or miniature flowers are held on tall plants, so check labels carefully before buying.
Choose a range of flower types to add interest to your planting design—try pairing tiny pom-poms with large cactus blooms for an exciting contrast. As well as their compelling flowers, many dahlias also offer colorful foliage. The dark bronze leaves of the ‘Bishop’ range, for example, are well worth including in borders and container displays.
Plant dahlias in a sunny spot with sufficient space to allow them to
grow to their full potential. Plant the tubers in the ground a few weeks
before the final frost in the late spring, or grow plants in pots
indoors; harden them off by placing them outside during the day for a
couple of weeks, and plant them out when the frosts have passed.