Red, White and Yellow Dahlia

What is Dahlia?

Dahlia is a genus of herbaceous, tuberous, bushy, perennial plants. Related to daisy, sunflower, zinnia and chrysanthemum, the plants are dicotyledonous. They belong to the Asteraceae family. Available as hybrids and in 42 species, they are grown as garden plants.

Flower forms vary from one specie to another, with each head on a single stem. The flowers range in diameter from 5cm to 30cm. Dahlia plants are octoploids because they have 8 homologous chromosomes instead of two like most plants.

Dahlia plants also have transposons, genetic materials moving from one place to another within an allele. Alleles showcase the great diversity of Dahlia plants. Ranging in height from 30cm to 2.4 meters, the plants have leafy stems. Dahlia flowers signify instability and dignity.

Most Dahlia species or cultivars don't produce scented flowers because they don't lure insects. However, they're brightly-colored and available in various colors except blue to attract insect pollinators. The plant was declared in 1963 as Mexico's national flower. The Aztecs grew the tubers for consumption. 

Dahlia Etymology

The plant was named Dahlia in honor of a student and the author of 'Observationes Botanicae', Anders Dahl. He was Carl Linnaeus' student and a Swedish botanist. German botanists later named it 'Georgina' before renaming it 'Dahlia'.

'Dahl' is a Swedish homophone meaning 'valley' or 'dal'. Sometimes, Dahlia is referred to as 'valley flower.'

Dahlia imperialis

Dahlia imperialis

I, KENPEI, Dahlia imperialis2, CC BY-SA 3.0

History of Dahlia

Dahlia seemed to be undeveloped until 1814, when the era of doubling began. Before another 25 years had passed, Dahlia sprung into the front ranks of garden lands. In 1826, the Royal Horticultural Society had already cultivated 60 Dahlia varieties. In 1841, one English dealer had over 1,200 varieties.

Today, it is not uncommon for the leading tradesmen to keep 500 -1,000 distinct varieties. In the absence of good records, it is conjectured that over 3,000 different names of varieties have  been published in catalogs. Most varieties are Show and Fancy types, spherical and regular as possible, and differing only in color.

At first, the distinction between the two types seem similar to that between “ self colored” and "variegated" flowers, in general. The former present to the view of only one color while the latter to two or more colors. 

Habitat - Where Does Dahlia Grow?

Dahlia is native to South America, Central America and Mexico. It grows at an altitude of 1500 to 3700 meters above the sea level in the mountains and uplands and vegetative zones of the 'pine-oak woodland'.

Dahlia Cultivation

Dahlia thrives in frost-free zones under USDA Zone 8. The plants can't grow in temperatures below zero. However, their tubers undergo dormancy in frosty temperate climates. During dormancy in winter, the tubers are removed from the ground and kept under frost-free, cool conditions.

Alternatively, the tubers are planted as deep as 15cm underground (or in soil) for protection from winter frost. Modern dahlia hybrids thrive in well-drained and properly watered soils. They require sufficient sunlight to actively grow during growth months.

Dahlia sherffii

Dahlia sherffii


Tall Dahlia cultivars require staking during growth. After garden Dahlia plants begin to flower, regular deadheading is recommended. Dahlias are prone to pests such as aphids, snails and slugs, capsid bugs and red spider mites.

They're also susceptible to diseases such as Dahlia smut, powdery mildew, verticillium wilt, grey mould, phytophthora and plant viruses. Ghost moth, angle shades, large yellow underwing and common swift Lepidoptera larvae feed on Dahlia plants.

Dahlias Cultivars

Dahlia species exceed 57,000 cultivars. Flower types vary from one cultivar to another. The flowers are grouped from Group 1 to 14 as follows:

Group 1: Dahlias with Single Flowers

Group 2: Dahlias with Anemone Flowers

Group 3: Collerette Dahlias

Group 4: Waterlily Dahlias

Group 5: Decorative Dahlias

Group 6: Ball Dahlias

Group 7: Pompon Dahlias

Group 8: Cactus Dahlias

Group 9: Semi Cactus Dahlias

Group 10: Miscellaneous Dahlias

Group 11: Fimbriated Dahlias

Group 12: Dahlias with Single Orchids

Group 13: Dahlias with Double Orchids

Group 14: Dahlias with Peony Flowers  

Dahlia Uses

Dahlias are used in floriculture, kidney clinical tests, diabetics treatment and Oaxacan cuisines.

Do you want to grow Dahlias at home? We have the right garden supplies and tools such as planter grow bag to get you started.