Dahlia
Dahlia
Dahlia blooms from July through October.
Mature size, hardiness zones, sun and the trait tags were checked against named botanical sources for this plant. The bloom months and water need on this page were not.
Growing Dahlia
Plant it in full sun. It prefers high water. It is hardy in USDA zones 8–10. Expect it to reach about 3.3 ft tall and 1.6 ft wide at maturity, in roughly 1 year.
When to plant Dahlia
Dahlia is tender: plant it out after the last frost, once the soil has warmed. In the middle of its hardy zones 8 to 10 range that means February or March; where spring comes later, it goes out later. Expect flowers from July to October.
Month-by-month timing for your zone is on the planting calendar: for the middle of its range, start with zone 9 in February.
Comes in 15 varieties across 6 colors
Same plant, same care - pick the color you are growing.
Good to know about Dahlia
Curated from university extensions, botanic gardens and other primary sources, with the source named on every note.
Safety
Toxic to dogs, cats and horses, causing mild stomach upset and mild dermatitis. The leaves and tubers can also irritate skin, worse with sun exposure. per ASPCA and NC State
Worth knowing
It is a heavy drinker, yet standing water rots the tubers. That is why every source pairs deep watering with sharp, well-drained soil. per NC State and UC IPM
Leave in ground, or dig?
In zones 7 to 10, NC State says tubers can stay under heavy mulch; UGA calls that unwise and digs them. Wet winters rot them, so lifting is safer. per NC State and UGA
Dahlia mosaic virus
There is no cure and no resistant variety. Start with certified virus-free tubers, pull and destroy mottled plants, and sanitize tools; aphid sprays do not stop it. per Utah State and University of Maine
Lift and store tubers
In cold zones, dig the clumps after frost, cure them a few days, then store at 2 to 10 C (35 to 50 F) in dry peat or sand. per Wisconsin and UGA
Tall types need staking
Tall dahlias flop under big, wind-catching heads. Drive a stake about 1.8 m (6 ft) long at planting so you do not spear the tubers later. per NC State and UGA
Attracts bees and butterflies
Dahlias attract butterflies, bees, and hummingbirds, and their long summer-to-frost bloom keeps feeding them late in the season. per NC State
What pairs well with Dahlia
Good companions share its growing conditions and add something it lacks: an earlier or later bloom, a lower carpet in front, or structure through winter.
Gardenia
Takes full sun to part sun and high water; opens in late spring and overlaps into this one's season; evergreen, so the bed keeps its shape through winter; a soft color beside the red.
Pansy
Takes full sun to part sun and moderate to high water; blooms in early spring, before this one opens; lower at 8 in, for the front of the border.
Stock
Shares full sun and moderate to high water; blooms in mid spring, before this one opens; lower at 1.6 ft, for the front of the border; pink sits close to red on the wheel.
Canterbury Bells
Shares full sun and moderate to high water; blooms in late spring, before this one opens; lower at 2.3 ft, for the front of the border.
English Daisy
Shares full sun and moderate to high water; blooms in mid spring, before this one opens; low at 6 in, to carpet the ground beneath; pink sits close to red on the wheel; they only overlap in zone 8.
Amaryllis
Takes full sun to part sun and moderate to high water; blooms in early spring, before this one opens; lower at 1.6 ft, for the front of the border; echoes the red.
Ranunculus
Shares full sun and moderate to high water; blooms in mid spring, before this one opens; lower at 1.3 ft, for the front of the border; pink sits close to red on the wheel.
Calla Lily
Takes full sun to part sun and high water; opens in early summer and overlaps into this one's season; lower at 2.3 ft, for the front of the border; a soft color beside the red.
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