Dahlias flourish in full sun and their vibrant colors are hard to beat, especially when planted large groups. Started from potato-like tubers in the spring, they start blooming by midsummer and reach their peak in the dog days of August, filling the gap between fading early summer annuals and fall-blooming asters and mums.
A mix of low-growing dahlias creates a colorful carpet under standard roses. Muckross Gardens, Killarney, Ireland.
Single-flowered orange dahlias blaze across a green landscape, drawing the eye toward the house. Oslo Botanical Gardens, Norway.
The blaze of color caught my eye from 100 yards away. Sandwiched between the lush lawn and a dark green hedge, the row of red-orange dahlias drew my eye like a magnet. The single, golden-centered blooms captured and reflected the colors of the yellow house and red-tiled roof behind them. Simple and stunning.
Dahlias flourish in full sun and their vibrant colors are hard to beat, especially when planted en masse. Started from potato-like tubers in the spring, they start blooming by midsummer and reach their peak in the dog days of August, filling the gap between fading early summer annuals and fall-blooming asters and mums.
The American Dahlia Society recognizes thousands of cultivars, from short window box pompons to 6-foot-tall giants with dinnerplate blooms. The society divides dahlias into classes based on the flower form, predominant color, and size. The flower form refers to the number, shape and arrangement of the petals. Some are long and needlelike, others short and rounded. Some flowers have a single row of petals around a button center, others resemble sea anemones or waterlilies. True blue is still elusive, but nearly every other flower color exists in the dahlia world, including bicolors and speckled blooms. Some even have bronzy foliage.
For mass plantings, I prefer cultivars that grow 12-24” high because they stand up to late summer wind and rain. Those with smaller flowers or fewer petals are also better for carefree landscapes. Taller dahlias, especially those with large flowers, often need support to keep their stems straight. These are perfect garden centerpieces, though, and they look great against a fence or trellis or among shrubs and fall-blooming perennials.
To truly appreciate the range of dahlia flower forms and colors, visit a dahlia society show or the floral display at a county or state agricultural fair this fall.
For more information, read this article: How to Grow Dahlias.
Green Goods Supervisor, Gardener’s Supply