Dreamy Dahlias: How To Identify Your Perfect Type

Minus some advance planning, fall usually spells the end of the garden. But if planted in spring, dahlias will flower non-stop through autumn. Lately, I’ve been waking up to crisp mornings only to discover more and more blooms. Who knew October could bring so many fresh flowers?

DAHLIAS BRING OUT THE CHILD

For some, dahlias may not be all that big a deal. But for me, the first time I saw the majestic, 10-foot flowers left an indelible memory. It was the 1960s, and I was a kid growing up in Delaware. Smack dab in the middle of suburbia, on the corner of two heavily-traveled streets, there was a small working farm. In the summer it produced fruits and vegetables. But in September, it grew dahlias.

And these weren’t your everyday dahlias, mind you. Many were the gigantic, dinner plate size; the kind that drives a kid mad with desire to jump out of the car just to be among them. Standing as tall as adults, they gently swayed in the breeze, solemnly saluting as we drove by. 

Craning my neck out the window, I’d watch until they disappeared, slowly dissolving into a sea of rainbow colors.

And thus began my love affair with these beautiful flowers.

SO MANY TYPES, SO LITTLE TIME

Dahlias are classified as tender perennials, meaning they may be annual or perennial, depending on the climate. They typically start blooming in August with other late-summer flowers. But the best thing about them is that they don’t stop blooming until the first frost, or roughly right around Thanksgiving.

And in spite of their reputation for towering stems and gigantic blooms, the plants come in all shapes and sizes. Dahlia types can range in height from the very tall specimens of my childhood to just under one foot. Planting the tubers is easy. Just dig a hole 6 to 8 inches deep and drop them in with the ‘eyes’ facing up. Three or more tubers per hole usually gives the most colorful effect.

FLOWERS AS BIG AS A FOOT

Still, it goes without saying that the most notable feature of all dahlias are the flowers. These can range in diameter from 2 inches to almost one foot. And among these, there are specific dahlia types, each with its own specifications. For example, there are species with single, double and semi-double petals. And there are unusual shapes like spherical or cactus. There are also types that resemble flowers such as anemones, peonies or orchids.

waterlily dahlia 'Pam Hayden'

Waterlily dahlia ‘Pam Howden’

Notwithstanding the variety, one thing all dahlia types have in common is their dazzling color. These flowers come in a seemingly infinite array, including all shades of pink, red, scarlet, orange, purple and yellow. Moreover, the flower petals often come painted with strips or tips of another color. (There are also creamy ones as well as many brilliant white species.) 

In sum, with so many options to choose from, how do you decide? One way is to familiarize yourself with the most common types. You may be surprised to find that some don’t look like the ‘typical’ dahlia. 

THE TEN MOST COMMON DAHLIA TYPES

Single-flowered dahlias feature a single row of flat or slightly cupped ray petals surrounding a central disc.

single-flowered dahlia

Single-flowered dahlia

Semi-double dahlias have two or more rows of petals surrounding a central disc.

semi-double dahlias

Semi-double dahlias

Mignon dahlias are similar to single dahlias except their petal florets are rounded and their disc flowers have no more than two rows.

mignon dahlia

Mignon dahlia with burgundy/black foliage

Anemone dahlias have an inner disc made up of tubular shaped florets and an outer ring of one or more rows of flat ray petals.

anemone dahlia 'Polka'

Anemone dahlia ‘Polka’

Orchid dahlias have open centers with just one row of ray florets surrounding a disc. The petals are often overlapping and curled for most of their length.

orchid dahlia

Orchid dahlia

Collarette dahlias have one row of flat petals surrounding a disc as well as an inner wreath of shorter petals called the ‘collar’.

collarette dahlia

Collarette dahlia ‘Mary Eveline’ plum red petals with white ‘collar’

Ball and Pompon dahlias are shaped like balls and feature double flowers with rounded or blunt tipped florets. Pompons are slightly smaller than ball dahlias.

pompom dahlias

Orange ball dahlias – notice the slightly flattened shape

pompom dahlia

The perfectly round pompon dahlia ‘Franz Kafka’

Decorative dahlias are doubles that feature flat, oval petals with tips on the end. Formal varieties have regular, evenly placed petals, while informal varieties tend to be arranged in a more haphazard way. Both varieties grow to over 40 inches.

decorative dahlia 'Lisa Dark Pink'

Decorative dahlia ‘Lisa Dark Pink’

Cactus and semi-cactus dahlias have narrow pointed petals that roll back on themselves, giving them a spiky look. Cactus types are rolled for their full length, while semi cactus types include a mix of flat and rolled petals. Both reach an average height of around 40 inches.

cactus dahlia

Orange cactus dahlia

semi-cactus dahlia 'Aloha'

Semi-cactus dahlia ‘Aloha’

There are many other varieties, including peony, waterlily and stellar, not to mention the celebrated ‘Dinner Plate’ which falls under numerous categories. The Miscellaneous Dahlias category alone includes hundreds of varieties.

Ready to add dahlias to your garden? Every year, among the ten top things I want to achieve or change in my garden, I resolve to plant more. Here’s how.

WHEN TO PLANT DAHLIAS

Dahlias are sold as tubers and need to be planted after the ground has warmed up and there’s no danger of frost. I usually plant mine in the late spring just around the time my tulips have faded. Plant the tubers in well drained soil in full sun for best results. You can also pot them up indoors a couple weeks beforehand to give them a head start.

dahlia tubers

Dahlia tubers need to winter indoors in a cool, but not cold, space

Dahlias are considered tender in my neck of the woods (Zone 6), but hardy outdoors in zones 8 to 10. That means that once they’re done flowering in the fall (or right after the first frost), I must dig them up. I then label them and store them in a dry spot in the basement. Click here for the USDA Plant Hardiness Map to see where you fit. 

To see photos of my garden designs, including plant lists, check out my Instagram at carole.herebydesign. I post seasonally from spring through fall. 

 

 

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