How to Grow Dahlia Plants in your Garden

Gardener's HQ Guide to Growing Dahlia

Although Dahlia are half hardy perennials they are normally grown as a half hardy annual by gardeners.

Depending on the variety they flower from the middle of summer to the first frost of winter.

Bigger varieties of Dahlia can reach heights of 1.5 metres and carry double flowers in a large range of colours.


Dahlia Tiptoes
Dahlia (tiptoes) pictures by KaCey97007.

How to Grow Dahlia

Quick Dahlia Growing Guide and Facts

Common Names: Dahlia.
Family: Asteraceae.
Life Cycle: Half hardy perennial usually grown as a hardy annual by gardeners.
Height: 12 to 60 inches (30 to 180 cm).
Native: South and Central America.

Growing Region: Zones 3 to 10. As a perennial in zones 9 and 10.
Flowers: Summer to first frost.
Flower Details: Purple, violet, yellow, red, pink, white. May have large flowers. Often have double flower heads.
Foliage: Blue-green. Ovate. Serrated.

Sow Outside: Tubers: plant about 6 or 7 inches (15 to 18 cm) deep with the eye at the top following the last frost. Seed: Cover seeds. Two weeks before last frost. Spacing: small species: 12 inches (30 cm); larger species 20 to 36 inches (50 to 90 cm).
Sow Inside: Pots. Germination time: one to three weeks. Temperature 68°F (20°C), ten weeks in advance. Transplant outdoors in mid spring, well after any chance of frost.

Requirements: Full sunlight. Soil pH 6 to 7.5. Deep soil. Humus rich. Add bone meal. Low nitrogen. Provide support. Occasional feed with bone meal. Pinch tips. Deadhead. Bring tubers indoors for the winter in areas of frost. Propagate: dividing in autumn.

How to Grow Dahlia

Dahlia can be grown from either seed or tubers.

If growing from tubers then plant with the eye towards the surface at a depth of about 15 cm (after the last frost of spring). The seeds of Dahlia should be lightly covered once sown (before the last frost of spring).

Ideally Dahlia should be planted into an area of the garden that is sunny; spacing depends on variety, small (30 cm / 12 inches), medium (45 cm / 18 inches), large (65 cm / 25 inches).

They like a soil that is of pH6 to 7.5, and that is enhanced by the addition of bone meal and humus, and low in nitrogen.

Seedlings of Dahlia can first be grown indoors for later transplanting. They should be started about 10 weeks before they are due to be put outside in the middle of spring.

They normally takes from one to three weeks to germinate in individual pots at about 18°C.

Dahlia Chick A Dee
Dahlia Chick A Dee by F. D. Richards.

Caring for Dahlias

Once growing in the garden Dahlias should be fed by the use of bone meal at the beginning and end of summer. Dahlia should be watered in prolonged dry periods, and weekly when in bloom.

Common Questions

How many members does the Dahlia genus have?

The Dahlia genus currently has approximately 42 species.

Do members of Dahlia make a good garden or landscaping plant?

Yes, Dahlia species are popular in gardens and landscaping for their vibrant, ornamental blooms.

Which Dahlia species are most frequently grown by gardeners?

The most frequently grown Dahlia species by gardeners is Dahlia pinnata (Garden Dahlia).

Are members of the Dahlia plant genus fragrant?

Most Dahlia species are not known for their fragrance, but are admired for their beautiful blooms.

What is the perfect location to grow Dahlia?

Dahlia plants thrive best in a location with full sun and well-drained soil.

Is Dahlia invasive in the USA, if so in which states?

Dahlia is not considered invasive in the USA.

How do I remove Dahlia plants from my garden?

To remove Dahlia plants, dig them up, ensuring to get all the tuberous roots to prevent regrowth.


The Dahlia genus is a group of tuberous plants native to Mexico, known for their vibrant, diverse flowers that come in a wide array of sizes, shapes, and colors. Dahlias are prized for their late summer to fall bloom times, filling the gap as many other flowers wane.

To grow Dahlias, plant tubers after the last frost in a sunny location with well-draining soil. They require consistent moisture but avoid waterlogged conditions. Support larger varieties with stakes, and consider removing some side buds (disbudding) to enhance the size and quality of the main flower.

I hope that you enjoyed this guide on how to grow Dahlia Plants. You may also enjoy the following Gardener's HQ Asteraceae growing guides: How to grow Safflower and Crepis plants.