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Dahlia pinnata

garden dahlia

Asteraceae Mexico and Central America

Attracts Pollinators Attracts Butterflies Container Friendly

Native to North America

SunFull Sun

WaterMedium

HardinessZones 8–11

Overview

Dahlia pinnata is a tuberous-rooted tender perennial that grows 90-150 cm (36-59 in) tall in a single season from a cluster of swollen storage roots. The stems are hollow, branched, and slightly woody at the base, carrying opposite, pinnately divided leaves 15-30 cm (6-12 in) long with toothed leaflets. Flower heads are 8-15 cm (3-6 in) across, each ringed by broad ray florets in purple, pink, red, or white around a central disc of yellow tubular florets. This wild species is one of the parents behind the many garden dahlia cultivars, and its heads are typically single or semi-double rather than the densely packed forms of bred types. Plants flower from midsummer until the first frost, then die back as the tops are killed by cold. The tubers are frost-tender and rot if left in freezing wet ground, so in cold regions they are lifted and stored dry over winter. Growth is fast, but the soft, sappy stems need staking in exposed sites.

Native Range

Dahlia pinnata is native to Mexico and Central America, where it grows on hillsides and in upland meadows. It has been cultivated for centuries and is naturalized in scattered warm-temperate regions.

Suggested Uses

Grown in summer borders, cutting gardens, and large containers for its long succession of blooms. The open-centred species form suits naturalistic and pollinator plantings, where bees reach the disc florets. Frost-tender tubers limit it to seasonal use or lifting in cold climates.

How to Identify

Identified by hollow branched stems, opposite pinnate leaves with toothed leaflets, and flower heads 8-15 cm (3-6 in) wide with a single or semi-double ring of broad ray florets around a yellow disc. The swollen, finger-like storage tubers separate it from fibrous-rooted daisies. Ray florets are purple, pink, red, or white.

Appearance

Size & Dimensions

Height3' - 4'11"

Width/Spread1'6" - 2'

Colors

Flower Colors

red

Foliage Colors

Fall Foliage Colors

Bloom Information

Bloom Period

~14 weeks

Summer Fall

Flower heads open from July through to the first autumn frost (midsummer to mid-autumn). Each head lasts one to two weeks, and removing spent heads extends the display into October in mild areas. Bloom is heaviest in late summer.

Detailed Descriptions

Flower Description

purple, pink, red, or white with a yellow centre

Foliage Description

mid-green

Growing Conditions

Sun Requirements

SunFull Sun

Requires 6-12 hours of direct sunlight daily

• Full Sun: 6+ hours of direct sunlight

• Partial Shade: 3-6 hours of direct sunlight

• Full Shade: Less than 3 hours of direct sunlight

Soil Requirements

pH Range6.0 - 7.5(Neutral)

357912

Soil Types

loam sand

Drainagewell drained

Water & Climate

Water Needs

Medium

Frost Tolerance

tender

Time to Maturity

one season from tuber

Care & Maintenance

Care Guide

Dahlia pinnata grows in full sun on fertile, free-draining soil kept evenly moist through the growing season. Tubers are planted after the last frost once the soil has warmed, and shoots emerge in two to four weeks. Soil pH from about 6.0 to 7.5 suits it. Tall stems are brittle and are usually staked before they reach full height. In zones colder than about 8, the tubers are lifted after the first frost blackens the foliage and stored in a dry, frost-free place. Slugs and earwigs feed on young shoots and petals.

Pruning

Spent flower heads are removed regularly through the season to prolong blooming. Stems are cut to the base after frost blackens the foliage. Pinching the growing tips early in the season produces a bushier plant with more stems.

Pruning Schedule

fall