Dahlia coccinea (scarlet dahlia) — tuberous perennial

Overview

Dahlia coccinea is a tuberous perennial in the genus Dahlia, part of the Asteraceae family. Dahlia coccinea grows best in full sun, and tolerates well-drained and fertile soils and neutral to slightly acidic pH. Its UK hardiness is rated H4. Suggested uses include borders and cut flowers. It is native to Mexico to Guatemala.

About

Dahlia coccinea is a tuberous perennial in the Asteraceae grown for its red flowers. Native to Mexico to Guatemala, it flowers in the UK from July to October. Plant on a south-facing, sheltered site in full sun with well-drained, fertile, neutral to slightly acidic soil and moderate moisture. It is suited to borders and to cutting for vases.

Wikipedia contributors, CC BY-SA 4.0 — Dahlia coccinea

About the genus

Dahlias come from the high meadows of Mexico, and somewhere in that heritage is the explanation for how they behave here: tender to frost, hungry, generous beyond all reason. No other plant gives you quite so much for so little. One tuber, planted after the last frost, becomes a shrub's worth of flowers by August — and the more you cut, the more they come.The range is faintly ridiculous. Tight pompoms, spiky cactus types, singles the bees adore, dinner-plates the size of your face. Whatever your garden's mood, there is a dahlia that agrees with it, which is probably why every generation falls out of love with them and then, a decade later, falls straight back in.They're at their best when much of the garden is winding down — late summer into autumn, flowering hard until the first frost calls time. I think of them as the encore. And they always play it.

Written by Henry

In the garden

A tuberous perennial in the daisy family, Dahlia coccinea originates from Mexico to Guatemala and has long been cultivated for its red blooms. In the UK it flowers from July to October, providing colour through mid- to late summer and into autumn. Give it a sunny, south-facing position sheltered from strong winds so stems and blooms remain upright; full sun is essential. It prefers well-drained, fertile soil that is neutral to slightly acidic, with moderate soil moisture rather than waterlogging. Hardiness is H4 (average), so it suits most UK gardens but will perform best where winter exposure is limited. Use Dahlia coccinea in mixed herbaceous borders or plantings where summer-to-autumn flower stems are wanted; it also works well as a source of cut flowers. Its tuberous perennial habit means the plant regenerates from underground tubers each year, making it a seasonal contributor to the border rather than a year-round foliage presence. With flowering from July through October, it supplies stems for late-summer and early-autumn floral arrangements.

Growing conditions

Best soil and position for Dahlia

Sunlight: full sun
Soil type: well-drained, fertile
Soil pH: neutral to slightly acidic
Soil moisture: moderate
Aspect: south-facing
Exposure: sheltered
UK hardiness: H4

Plant details

Dahlia coccinea size, habit and characteristics

Plant type: tuberous perennial
Suggested uses: borders, cut flowers
Native to: Mexico to Guatemala

Care notes

Pruning and caring for Dahlia coccinea

Cultivation: plant tubers in spring after frost; provide support for taller varieties; deadhead to encourage flowering
Pruning: remove spent flowers; cut back after flowering season
Propagation: tuber division, seed