The colorful dahlia

By: Maggie & Pippa C.
Date: 18 March 2026

What it is

Dahlia is a group of flowering plants originally from Mexico and Central America, loved by gardeners around the world for their showy, colourful blossoms. Dahlias belong to the sunflower family, but their flowers look quite different — in fact, they come in so many shapes, sizes and colours that gardens can feel like a celebration when they’re in bloom.

Gardeners often grow them as annuals or perennials, depending on the local climate and how they’re cared for. Dahlias are especially popular in summer and autumn gardens because they bloom late in the season, often from July through October.

How it looks

Dahlias grow from tubers — thickened underground stems that store energy for the plant. Depending on the variety, a single plant can reach 30–150 cm tall or more. Some small dwarf varieties stay under 50 cm, while larger types can be closer to 1.5 m. Their stems are sturdy, often branching, and their leaves are typically green and shaped like elongated ovals.

The flowers are the showstopper. Dahlias come in dozens of different forms — from simple open petals to tightly packed, globe-shaped blooms that can be 10–25 cm across or bigger. Colours range from white, yellow and orange to red, purple, pink and even multicoloured or striped varieties. Because of this variety, dahlias are a favourite for cut flowers and floral displays.

Where it came from

In the wild, dahlias grow in the mountainous regions of Mexico and Central America, where they experience warm nights and bright days — conditions that encourage lots of flowering. Indigenous peoples used dahlias both as food and medicine long before they were introduced to Europe in the late 18th century.

Its varieties

European gardeners began cultivating dahlias in the 1700s, and since then breeders have selected countless varieties with bigger blooms, stronger stems and a huge range of colours. Modern dahlia collections include small pom-pom types, elegant single blooms, cactus-like spikes and massive dinner-plate flowers.

How to grow it

Dahlias are usually grown from tubers planted in spring after the danger of frost has passed. They like:

• Full sun — at least 6–8 hours a day
• Well-drained, fertile soil
• About 30–60 cm between plants depending on size
• Regular watering, especially during hot dry spells

Once dahlias start growing, staking taller varieties helps support the stems so they don’t flop over under big blooms. Deadheading (removing spent flowers) encourages new blooms throughout the season. In colder climates, tubers are often dug up after the first frost and stored over winter, then replanted in spring.

Why it is popular

Dahlias are popular because they offer long-lasting colour from mid-summer into autumn, and because the variety is almost endless. Whether you want neat garden beds, tall border plants, striking cut flowers for vases, or eye-catching colours for flower shows, there’s usually a dahlia to fit the bill. Gardeners also enjoy the challenge of growing and breeding new forms.