Dahlias are stunningly beautiful late-season flowers that bloom in a rainbow of colors from mid-summer through fall. Dahlias are perennials in zones 8 and higher; In cold climates, they must be dug up and stored until spring. Learn how to plant dahlia bulbs and great tips on how to grow dahlias!
About dahlia flowers
Dahlia is a genus of bulbous plants belonging to the Asteraceae family, which also includes sunflowers, daisies, chrysanthemums, zinnias, and of course, asters.
Picking a favorite dahlia is like browsing through a button box. Flowers can range in size from dainty 2-inch lollipop-style pom-poms to giant 15-inch “dinner plates.” Most varieties grow 4 to 5 feet tall. Plus, dahlias grow in a wide range of beautiful colors including white, yellow, orange, pink, deep pink, red, dark red, lavender, purple, and black, light mix, bronze, flame, dark mix, variegated, and bi-color!
Tubers are planted in the ground in late spring and generally bloom from July to the first fall frosts. Dahlias are perfect for a border garden and make beautiful cut flowers. Growing Vegetables? Put a row of dahlias on the border where they won’t shade your edibles.
Are dahlias perennials?
It depends. Dahlias are considered a tender perennial in colder regions of North America. From hardiness zone 8 they are reliably hardy. In colder zones, dahlias can either be treated as annuals or the bulbs can be dug up after the first frost and stored indoors for the winter and replanted in spring. It can vary for gardeners in zones 6 and 7 and some are lucky enough to keep tubers in the ground. (See which hardiness zone you’re in!)
Dahlias love moist, temperate climates and full sun. Although dahlias aren’t well suited to extremely hot climates (like South Florida or Texas), they’ll brighten up any sunny garden with a growing season of at least 120 days.
Dahlias thrive in 6 to 8 hours of direct sun, especially the morning sun, and they benefit from wind protection. When planting, consider their size at maturity. They grow best in rich, well-drained soil with a pH of 6.0 to 7.5. Amend heavy clay soil with old manure or compost to lighten and loosen the soil structure for better drainage.
When to plant dahlias
Dahlias do not tolerate cold soil. Plant when the soil has reached 15°C and all danger of frost has passed.
Planting dahlias a few days after tomatoes are planted in the ground is a good rule of thumb.
Some gardeners start tubers in containers a month in advance to jump into the season. Medium to dwarf sized dahlias do well in containers.