Dahlia: Planting, Care and Growing Tips

Botany and description

Native to the highlands of Mexico and Central America, the Dahlia belongs to the large Asteraceae family, like daisies, asters or echinaceas. There are 30 species and close to tens of thousands of cultivars: today nearly 20,000 horticultural varieties are present worldwide. Most are derived from Dahlia pinnata and D. coccinea. Discovered in the 16th century, the Dahlia was only introduced to Europe two centuries later. The Dahlia imperialis, the botanical species which bore single flowers, was then very different from the modern Dahlia.

From its origins in the dry Mexican landscapes, it has retained its love for heat and sun but a congenital sensitivity to cold! Moderately hardy, the Dahlia is very sensitive to cold, its tubers must be overwintered in most of our regions as it fears frost. It cannot withstand temperatures consistently and frequently below -5°C. But, stored all winter well protected from frost, it will flower again for years to come.

Today, the Dahlia has become popular everywhere in France, found in all summer flower beds. There are two main types: large-flowered Dahlias with tubers and dwarf bedding Dahlias easily propagated by seed. Among the most appreciated and widespread: Anemone-flowered Dahlias, Orchid-flowered Dahlias, Collarette Dahlias, Decorative Dahlias, Pompon and Ball Dahlias, Cactus and Semi-Cactus Dahlias, Giant Dahlias, Dwarf Dahlias single and double.

Dahlia flower shapes vary by variety: ball, waterlily or cactus-flowered…

The Dahlia is part of a vast family with very varied forms, colours and heights. The tallest specimens easily reach 1.50m in height, even more in fertile soil, with a spread of 45 to 80cm. Among them is the Dahlia Imperialis, the botanical ancestor of the Dahlias in our gardens which can reach up to 3m in height. Intermediate Dahlias grow between 80cm and 1.10m. The dwarf varieties, between 0.25 and 0.70cm, do not require staking.

This perennial has swollen, tuberous roots, clustered together like small potatoes. Edible, they were initially cultivated for consumption. But their rather tasteless roots were quickly abandoned in favour of the plant’s exceptional flowering.

From its bushy, erect clump emerge rigid, tubular, upright, hollow and branched stems bearing inflorescences from July to October (until November in temperate climates) that renew themselves all summer without interruption.

The Dahlia flower has a strong character, such a pronounced, exuberant personality that it stands out among thousands. Its solitary capitulum inflorescences are formed by one or more rows of radiating ligules surrounding, depending on the variety, a central disc of more or less visible pistils. The flower diameter varies from 10cm to 25cm or more! They are classified by the size of their inflorescences:

• Giant: over 25cm in diameter (Giant Dahlias)
• Large: 20 to 25cm in diameter (Cactus Dahlias, Ball Dahlias)
• Medium: 15 to 25cm in diameter (Waterlily-flowered Dahlias)
• Small: 10 to 15cm in diameter (Anemone-flowered Dahlias, Collarette Dahlias, Decorative Dahlias)
• Miniature: under 10cm in diameter (Pompon Dahlias)

Giant Dahlia ‘Emory Paul’-‘Mel’s Orange Marmalade’-‘Burlesca’

Giant Dahlias, like the Dahlia ‘Emory Paul’, bear enormous flowers that can reach up to 35cm in diameter, the size of a plate.

The other variable of the Dahlia is its flower shape, which forms the basis of classification. These ligulate, unscented flowers are single, semi-double or very double. The shape of the ligules varies by cultivar: rolled, flat, lacy…

The Decorative Dahlias have no central disc but large double flowers with generally flat petals, rounded at the tip and slightly curved, sometimes resembling a waterlily or a camellia flower. The elegant Semi-Cactus or Cactus Dahlias bear long, rolled and pointed petals forming a shaggy pompon centre reminiscent of a cactus flower like the Dahlia Mel’s Orange Marmalade. In this group, the narrow, very tapered ligules of the capitulum are rolled for more than half their length. The ‘lace’ cactus are characterised by large, cut flowers with tapered petals, flat or rolled and ending in forked tips, resembling lace.

Others, formed by a crown of wider ligules surrounding a very double centre of smaller florets, resemble an anemone. Some Dahlias have long, curved or reflexed ligules, arranged in a star shape recalling an orchid.

The Collarette Dahlias or single-flowered Dahlias have just a simple crown of petals around a central disc encircled by an inner collar of shorter ligules (the centre and tips often offer a striking contrast as in the Dahlias ‘Pooh’ or ‘Fashion Monger’).

Full of whimsy, the Honka Dahlias bear star-shaped flowers, with thin, very rolled and separated petals around an orange centre, making them resemble delicate windmills or curious spiders.

At the opposite end are the very graphic Pompon Dahlias, whose tubular ligules form a spherical inflorescence about 10cm for the largest, sometimes flattened at the top, with a honeycomb-like structure, similar to a beehive like the Dahlia ‘Burlesca’. The Ball Dahlias bear flowers similar to pompon Dahlias, but larger, with a diameter that can reach 12cm.

Dahlia flowering offers an incredible richness of colour: its flowers come in an infinite palette ranging from light pink to lilac pink, from wine-lees to crimson red, from apricot to carmine salmon, from pure white to café au lait or primrose yellow, from indigo violet to lilac blue (‘Worton Blue Streak’ is the bluest cactus at the moment!).

With excellent vase life, Dahlia flower heads make wonderful summer bouquets full of colour. Some varieties like the Dahlia ‘Karma Lagoon’ have been specially developed for cut flowers.

Deciduous, the abundant foliage brings a certain lushness and highlights the exotic colours and voluptuous shapes of the flowers. The opposite, finely toothed leaves, 20 to 50cm long, are either pinnate or very rounded and divided into three to five leaflets, more or less leathery. The foliage colour also offers beautiful variations, ranging from tender green to emerald green or bronze green or even purple (Decorative Dahlia ‘Purple Flame’, Happy Single ‘Juliet’, Dahlia Happy Single ‘Flame’) depending on the different types.

Dahlia ‘Pooh’ – ‘Happy Single Juliet’ – Honka ‘Pink’- ‘Fashion Monger’

Contrary to popular belief, the Dahlia is not difficult to grow, but does require some attention. It will only be happy and floriferous in warm and sunny conditions. While it adapts to all soils, it thrives in fertile soil, rich in humus, fresh and well-drained, preferably neutral, neither acidic nor chalky. It likes light soils, but which remain fresh and kept sufficiently moist with a good mulch during the growing season. The Dahlia does not tolerate stagnant water, especially in spring and autumn. Fresh soil allows it to develop vigorously. It requires, to flower well, soil rich in organic matter. It will never be lush and will struggle in poor, sandy soil. Tall Dahlias are quite resistant to wind or heavy rain. If you want to avoid rather unsightly staking, it’s better to give them a place sheltered from prevailing winds which could make the stems bend.

Dahlia ‘Ridel’ and Hordeum jubatum (foxtail barley)- credit-Noun – MAP

A staple of cottage gardens, the Dahlia is a versatile flowering plant that brings colour, texture and originality to borders, rockeries, flower beds, containers as well as the vegetable garden. The Dahlia can be grown alone, but is preferably planted in groups, in the middle or at the back of sunny borders, combined with grasses, other vigorous perennials that will act as supporters, preventing their flowering stems from bending unattractively. Dwarf varieties are reserved for borders or planters. Magnificent in borders, Decorative Dahlias make excellent cut flowers for bright, colourful summer bouquets.

This plant was named “dahlia” in honour of the Swedish botanist Andreas Dahl.

Main species and varieties

Anemone-Flowered Dahlias

Cactus and Semi-Cactus Dahlias

Collarette Dahlias

Decorative Dahlias

Giant Dahlias

Dwarf Single and Double Dahlias

Pompon and Ball Dahlias

These are characterised by large blooms with a ring of flattened petals surrounding a densely double centre of smaller florets. Their unique, sometimes contrasting colours inevitably catch the eye. They include tall varieties perfect for perennial borders as well as compact types ideal for pots or stunning summer bouquets.

Dahlia Blue Bayou

its red, frizzy heart contrasts beautifully against a lilac-coloured ring. Ideal for rockeries, borders, and containers.

• Flowering time August to November
• Height at maturity 1 m

See the product sheet

Dahlia Anemone Soulman

We love its captivating garnet-red hue.

• Flowering time August to November
• Height at maturity 70 cm

See the product sheet

This horticultural category is defined by their flower shape—resembling a cactus bloom! They bear very large double flowers, 12–20 cm across, with a delightfully ruffled appearance and pointed, tightly rolled petals. Semi-cactus varieties have similar blooms but with narrower, less tightly curled petals. The tallest make striking focal points at the back of borders, while dwarf cactus Dahlias (under 60 cm tall) are perfect for edging or front-of-border planting.

Dahlia Urchin

Its ruffled deep raspberry blooms catch the eye and make stunning cut flowers.

• Flowering time August to November
• Height at maturity 1 m

See the product sheet

Dahlia Blue Record

Its flowers mirror those of taller varieties, just with a smaller diameter (10 cm).

• Flowering time August to November
• Height at maturity 60 cm

See the product sheet

This group features single blooms with a contrasting, ruffled centre. The broad, flat outer petals form a neat ring around a collar of shorter petals, revealing a yellow heart. The collar, often in a different colour, creates striking contrast. Dwarf varieties (under 40 cm tall) are sensational in flower borders and pots.

Dahlia 'Pooh'

A striking contrast with its large yellow blooms and red-and-yellow collar.

• Flowering time August to December
• Height at maturity 1,20 m

See the product sheet

Dahlia 'Impression Fantastico'

An exceptionally elegant dwarf Dahlia with mahogany petals and a white collar. Stunning in pots.

• Flowering time August to December
• Height at maturity 40 cm

See the product sheet

These stand out with their large, full double blooms composed of numerous broad, flat petals with rounded or slightly curled tips. This diverse group includes giants with flowers over 20 cm across as well as smaller varieties evoking camellias, waterlilies, or chrysanthemums.

Dahlia Café au Lait

We love its enormous cream blooms—a rare colour among Dahlias.

• Flowering time August to November
• Height at maturity 1,20 m

See the product sheet

Dahlia Duke Duweno

A rare variety with intense purple pompons.

• Flowering time August to December
• Height at maturity 80 cm

See the product sheet

Dahlia Happy Butterfly

A striking variety with yellow waterlily-like blooms flamed with red.

• Flowering time August to November
• Height at maturity 1,10 m

See the product sheet

These bear the largest flowers of all. Majestic in stature, their stems reach up to 1.5 m tall, topped by plate-sized blooms up to 35 cm across! With their subtle or intense colours, they make spectacular backdrops in perennial borders or vegetable gardens. Staking is often required.

Dahlia Myrtle's Folly

We adore its ruffled peach blooms edged in lilac-pink.

• Flowering time August to November
• Height at maturity 1,20 m

See the product sheet

Dahlia Barbarossa

Its enormous scarlet-red blooms will be the garden’s star attraction!

• Flowering time August to November
• Height at maturity 1,20 m

See the product sheet

Their compact size makes them ideal for pots, containers, or edging flower beds. This group includes the Gallery Dahlias (around 45 cm tall), offering continuous blooms in opulent colours and forms; dwarf cactus Dahlias (50–60 cm tall), stunning with their large double blooms; and the Happy Single collection, with vibrant single blooms reaching 60–80 cm.

Dahlia Happy Single Juliet

Its candy-pink single blooms contrast beautifully against purple foliage—stunning!

• Flowering time August to November
• Height at maturity 60 cm

See the product sheet

These are distinctive for their perfectly spherical, honeycomb-like blooms. The difference between pompons and balls lies in size: pompons are smaller (up to 10 cm), while balls range from 6–12 cm. These spherical flowers are perfect for creating rounded bouquets and adding a graphic, colourful touch to borders.

Dahlia Pompom Burlesca

A reliable choice with gorgeous acid-pink blooms tinged with orange.

• Flowering time August to November
• Height at maturity 90 cm

See the product sheet

Dahlia Icoon

A sunny effect with its bright yellow blooms tipped with ruby.

• Flowering time August to November
• Height at maturity 1 m

See the product sheet

Planting dahlias

When to Plant?

With Dahlias, haste makes waste – timing is key: planted too early, the first shoots risk being devoured by slugs. Tubers stored indoors over winter should be planted in spring, in March after the last frosts. In colder regions, wait until late April or early May, once the soil has warmed and can be worked. Simply store purchased tubers in their packaging in a frost-free spot until the right planting time.

Where to Plant?

Dahlias grow almost anywhere in France. The essential condition for thriving dahlias is planting them in full sun. Second requirement: choose well-drained soil where water doesn’t pool, especially in spring and autumn. Dahlias prefer light soils that stay cool and sufficiently moist with good mulching during the growing season. Waterlogged conditions, however, may cause tuber rot.

Though they adapt to most soils (avoiding overly acidic or chalky ground), they flourish in fertile garden soil, rich in humus, cool, well-drained, and preferably neutral. Dahlias are greedy feeders: to bloom well and grow vigorously, they need rich soil preparation. If unsure about soil fertility, add compost or manure in autumn.

Dahlias can be planted in borders or vegetable gardens

Tall Dahlia varieties struggle in strong winds or heavy rain. Exposed sites may dry foliage or topple stems. Shelter them from prevailing winds. Staking may be essential for tall Dahlias to support flower heads, preventing stems from snapping in gusts, especially when grown alone. To avoid flopping in mixed borders, plant Dahlias alongside other plants or shrubs for natural support.

When planting, allow adequate space in borders. Ensure each plant remains accessible for feeding, staking, disbudding, and winter storage.

While adaptable to any garden setting, Dahlias shine as mid-border or backdrop plants, adding vibrant colour.

Dwarf varieties suit sunny beds, path edging, or container growing on terraces or balconies. Potted Dahlias need quality compost, regular watering, and bulb fertiliser.

How to Plant?

Dahlias are heavy feeders. To meet soil nutrition needs, dig in compost or manure in autumn or just days before planting. For heavy soils, mix in grit and compost to improve drainage.

Planting Tubers

From mid-April, once soil is workable, plant your Dahlias:

• Space tall varieties 80–100 cm apart
• Space compact varieties 30–50 cm apart
• Prepare a 20 cm-deep hole, blending in a handful of bone meal or dried blood with crumbled garden soil. Dahlias crave rich soil.
• Position tubers with the crown 5 cm below soil level.
• Cover with 10 cm of soil.
• Insert stakes for tall varieties (avoid damaging tubers) – this also marks planting spots!
• Water thoroughly, then regularly for 6 weeks to establish roots.
• Scatter slug pellets to protect emerging shoots.
• Mulch once plants are established.

→ Also read: Planting Dahlias: 8 Common Mistakes to Avoid and How to Force Dahlias for Earlier Blooms

Overwintering dahlia tubers

Dahlias are extremely sensitive to cold and fear frost. In regions with harsh winters where temperatures regularly drop below -5°C, lifting the tubers is essential if you wish to keep them alive. In areas with mild winters where frosts are light and infrequent, and in well-draining sandy soil, the tubers can remain in the ground over winter, simply protected by a thick mulch of dry leaves or straw. Lifting the tubers allows for division and potting up to encourage earlier flowering.

In late October or early November (not before, as the roots would not have sufficient reserves for winter), when the plant weakens and the first frosts begin to blacken the leaves, it’s time to dig up the tuberous clumps. The goal is simple: to protect them from frost!

• Once the foliage has blackened from frost, cut the stems back to 15 cm above ground level.
• Carefully dig up the tubers using a garden fork.
• Remove as much soil as possible from between the tubers.
• Label each clump at the base of the stem to easily identify them in spring.
• Place the tubers on a layer of peat, dry sand, or dry leaves in a cardboard box or deep crate.
• Cover the tubers with a layer of peat or dry leaves.
• Store them away from light, draughts, rodents, and—most importantly—frost in a dry, cool, well-ventilated, and dark location where temperatures do not exceed 4–5°C (such as a dry cellar, frost-free garage, or attic). Under these ideal conditions, dahlias store very well with minimal risk of loss.
• Regularly check the tubers for signs of disease.

→ Read also: How to overwinter dahlias to protect them from frost? and Overwintering Dahlias: Should You Lift Them?

Care and Maintenance

Dahlias are relatively easy to grow but do require some attention. A few simple steps will ensure a summer full of blooms.

• In spring, protect young shoots from slugs.
• During the growing season, Dahlias are thirsty plants. Water generously when buds are forming.
• In July, mulch with a 2 cm layer of dry straw or peat to retain moisture throughout summer. Water the mulch.
• Stake the stems of tall varieties if needed as the plant grows.
• Tie in young stems
• 2-3 weeks after planting, pinch out the growing tip to encourage branching and more flowers, especially if the tubers produce only a single stem. This will create a bushier plant that is more resistant to bad weather and may not need unsightly staking.
• For larger blooms, pinch out side buds.
• Remove small shoots at leaf axils – flower heads will grow bigger as a result.
• Deadhead spent flowers to encourage new blooms and extend the flowering period.
• Water regularly, twice weekly in hot weather, at the base of the plant rather than on foliage.
• In late summer, apply organic fertiliser to boost growth.
• In autumn, work well-rotted manure or compost into the garden soil.

Pests and Diseases

Dahlias are vulnerable to slug attacks in spring when tender young shoots emerge – use fern manure or wood ash as deterrents. Later in the season, aphids may target young stems with buds – treat with diluted black soap. Earwigs adore tender petals but their feeding doesn’t harm the plant’s health. Deficiency symptoms (thin stems, yellow leaves, stunted growth) indicate poor nutrition – apply compost mulch and complete fertiliser. Grey mould can affect tubers in excessively damp conditions.

→ Learn more about dahlia pests and diseases in our advice sheet!

Propagation

By cuttings

This is the best way to obtain a large number of plants, but it is rather tedious; we recommend dividing your tubers instead. Cuttings are taken from tubers that have been pre-sprouted. In early March, bring out the roots stored all winter and place them in a fresh mixture of compost or moist peat. It will take about three weeks for shoots to appear. Take the cuttings when these shoots reach around ten centimetres in length. Potted under a cold frame and then repotted, they can be planted out in early June.

By dividing tubers

This is the simplest method. It can be done just before planting.

• In spring, around late March, take the roots that have overwintered in storage.
• Use a sharp knife or secateurs to divide the tubers into two or three pieces, ensuring each has a portion of the old stem with an eye, from which new shoots will emerge.
• Dust the cuts with charcoal.
• Only plant in mid-April to early May if small buds have appeared; otherwise, wait and water to encourage their growth.

Watch our video tutorial on dividing dahlias:

To learn more, check out our tutorial: How to Multiply Dahlias: The Right Steps. Also read: How to Sow Dahlias?

Pairing

A staple of cottage gardens, the Dahlia is a versatile flowering plant that brings colour, texture and originality to borders, rockeries, flower beds, containers as well as the vegetable garden. Dahlias can be grown as standalone specimens but are best planted in groups in the middle or back of sunny borders, paired with ornamental grasses (Panicum, Molinia, Calamagrostis) or other vigorous perennials (Cosmos, Asters, Echinacea, Cannas) which will act as natural supports, preventing their flower stems from flopping unattractively.

Dahlias ‘Purple Flame’ – Calamagrostis – Asters – Echinacea

The Landscape, Pompon or Honka varieties with pointed petals create airy displays. Compact varieties like the Gallery series or dwarf Happy Single dahlias, as well as Collerette types (‘Impression Fantastico‘), are ideal for edging or containers. Stunning in borders, decorative Dahlias also make excellent cut flowers for bright, colourful summer bouquets.

Need more inspiration? Explore our guide: “Dahlias: Perfect Pairings for Your Garden”