Types of Dahlias

What are the different types of dahlias?

Dahlias are classified by bloom form, size, and petal structure. The American Dahlia Society (ADS) recognizes 20 official forms, ranging from single-petaled open-centered blooms to tightly packed 12-inch dinnerplates with hundreds of petals. Size classification runs from miniature (under 2 inches) to giant AA (over 10 inches).

Understanding dahlia forms helps you choose the right plant for your purpose — whether that is cutting flowers for the house, creating a bold garden border, or growing a manageable plant without extensive staking. This guide covers the forms most common in US home gardens, with notes on performance, care difficulty, and best uses.

ADS bloom size classification

Before covering forms, size is useful to understand. The ADS assigns a letter code to each registered variety based on bloom diameter.

Most dahlias sold at US garden centers fall in the B–BB (4–8 inch) range. Dinnerplate types are AA–A.

The 20 ADS dahlia forms: overview

Rather than cataloging all 20 forms in equal depth, this guide focuses on the 7 most widely grown in US gardens. The remaining forms (orchid, novelty open, fimbriated, etc.) are grown primarily by collectors and ADS show exhibitors.

Dinnerplate dahlias

Dinnerplate dahlias are the giants of the genus — blooms 8 to 12 inches across with fully double petals in a rounded, symmetrical form. They include both decorative and formal decorative dahlia forms grown to giant size.

These are the dahlias that stop people on the sidewalk. A well-grown dinnerplate dahlia in full bloom is a genuinely spectacular sight. They require more work than smaller forms:

• Staking: Every dinnerplate dahlia must be staked at planting. A 5–6 foot bamboo stake or metal garden stake is the minimum. The stem supporting a 12-inch, rain-soaked bloom will snap without support.
• Disbudding: To grow dinnerplate-size blooms, remove the two smaller side buds that appear at each bud cluster. This directs all energy into the single central bud. Skip disbudding and you get more blooms, each smaller.
• Watering: Consistent moisture is essential. Irregular watering during bud development produces blooms that open unevenly.

Popular dinnerplate varieties available in the US:

• ‘Café au Lait’ — Creamy blush-peach; the most photographed dahlia in the US. Blooms 8–10 inches.
• ‘Otto’s Thrill’ — Pink, prolific, ADS exhibition winner. Blooms 10–12 inches.
• ‘Penhill Dark Monarch’ — Deep burgundy-black; dramatic in arrangements.
• ‘Kelvin Floodlight’ — Clear yellow; one of the largest dinnerplates available.

Decorative dahlias

Decorative dahlias have fully double blooms with broad, flat-tipped petals arranged in a slightly informal, layered pattern. They are the most common dahlia form in US gardens and include both formal decorative (very symmetrical) and informal decorative (slightly irregular) classifications.

Decorative dahlias range from BB (4–6 inches) to A (8–10 inches). At the smaller end of that range, they are manageable, productive, and widely available. Many popular dahlia varieties sold at garden centers — ‘Arabian Night,’ ‘Karma Choc,’ ‘Thomas Edison’ — are decorative types.

Key characteristic: Flat-tipped petals (blunt ends) distinguish decorative dahlias from cactus dahlias (pointed petals) and ball dahlias (recurved petals).

They are excellent cut flowers but have a shorter vase life than cactus types — 5–7 days with proper conditioning.

Ball dahlias

Ball dahlias produce fully double, sphere-shaped blooms with petals that curl inward at the tips, creating a round, geometric shape. They range from 2 to 4 inches (miniature ball) to 4–6 inches (ball). Every petal curves inward; the overall form is nearly a perfect sphere.

Ball dahlias are among the best for US home gardeners for three reasons:

1. Self-supporting: Most ball varieties stay under 4 feet and do not require staking
2. No disbudding needed: Ball dahlias are naturally prolific — let all buds develop
3. Long vase life: The tight, compact form resists petal shattering; balls last 7–9 days in a vase

Popular ball varieties in the US:

• ‘Sylvia’ — Clear pink; miniature ball; 40+ blooms per plant per season
• ‘Inland Dynasty’ — White with lavender edge; medium ball
• ‘Cornel’ — Bright red; prolific; excellent for cutting (our Cornel Bronze Dahlia guide covers its copper-toned relative)

Pompon dahlias

Pompon dahlias are similar in shape to ball dahlias but smaller — under 2 inches. They are perfectly round, fully double, and almost whimsical in scale. A mature pompon plant is covered in dozens of golf ball-sized blooms.

Pompons are the most child-friendly dahlia form. The small blooms are easy to cut, arrange, and give away. They make excellent filler flowers in arrangements alongside larger dahlias.

Pompon dahlias are naturally compact — most stay under 3 feet — and rarely require staking. They are among the easiest dahlias to grow, making them ideal for gardeners new to dahlias.

Popular US pompon varieties:

• ‘Small World’ — White; ADS show winner
• ‘Bantling’ — Deep red; prolific
• ‘Moorplace’ — Purple; classic pompon form

Cactus dahlias

Cactus dahlias have fully double blooms with pointed, narrow petals that are rolled or quilled along most of their length — the opposite of the flat-tipped petals of decorative forms. The overall effect is spiky, dramatic, and very different from the round dahlias most people picture.

There are two cactus subtypes:

• Straight cactus: Petals are pointed and relatively straight
• Incurved cactus: Petals curve inward toward the center of the bloom

Cactus dahlias are among the best cut flowers in the dahlia world. The rolled petals are more resistant to bruising and shattering than the broad, flat petals of decorative types. Cut cactus dahlias last 8–10 days in a vase.

Popular US cactus varieties:

• ‘Shooting Star’ — Yellow with red tips; dramatic bicolor
• ‘Giggles’ — Pink; medium cactus; prolific
• ‘Barbara’s Pastels’ — Soft peach-apricot; widely available in US specialty dahlia nurseries

Collarette dahlias

Collarette dahlias are single-petaled blooms with an open center surrounded by a second row of shorter petals (the collar) between the outer petals and the center disc. They are one of the few dahlia forms with an accessible, open center — making them the most pollinator-friendly dahlias.

If you are growing dahlias with pollinators in mind, collarette is the form to grow. Bees, hoverflies, and parasitic wasps can access the pollen and nectar in the open disc — something impossible in fully double forms where the disc is obscured by petals.

Popular collarette varieties:

• ‘Pooh’ — Orange with yellow collar; classic
• ‘La Luna’ — Cream and yellow; excellent for arrangements
• ‘Chimborazo’ — Red outer petals, white collar; very striking

See our attract pollinators to your garden guide for how to integrate dahlias with other pollinator plants.

Anemone dahlias

Anemone dahlias have a single or double ring of flat outer petals surrounding a dense, pincushion-like center of shorter tubular petals. The overall look is similar to an anemone flower — hence the name.

These are specialty dahlias, less common in US garden centers but available through specialty dahlia suppliers and the American Dahlia Society member sales. They are compact, easy to grow, and interesting for cut flower work.

Dahlia form comparison for US gardeners

Growing dahlias by USDA zone

Dahlias grow as summer annuals in every US zone. Tuber overwintering depends on your zone.

For planting depth guidance, our how deep to plant dahlia tubers guide covers the specifics — dahlias planted too shallow tend to fall over; planted too deep, they rot.

Choosing dahlias for specific uses

For bold garden display: Dinnerplate and large decorative forms — ‘Café au Lait,’ ‘Otto’s Thrill,’ ‘Penhill Dark Monarch’

For cutting flowers: Cactus, ball, and small decorative — long vase life, shippable form, prolific production

For beginners: Ball and pompon — no staking, no disbudding, very forgiving

For pollinators: Collarette and single-flowered forms — open centers accessible to bees and beneficial insects

For small gardens or containers: Pompon and miniature ball — compact plants under 3 feet, no staking

Where to source dahlia tubers in the US

The American Dahlia Society (dahlia.org) maintains a breeder and seller directory. US specialty suppliers include Swan Island Dahlias in Oregon, Floret Farm in Washington state, and Old House Gardens in Michigan.

For our specific variety reviews, see our Wizard of Oz Dahlia guide and Cornel Bronze Dahlia guide — two popular US varieties with very different growth habits.

For summer annuals that complement dahlias in the garden, our annuals that bloom all summer guide and zinnias guide cover compatible plants that extend your cutting garden season from May through frost.