A cactus dahlia blooming in my garden
Without some advance planning, fall often spells the end of the show in the garden. But I’ve learned from experience that if you plant dahlias in late spring, they’ll flower through autumn like it’s summer. 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
In the casual opinion of most, 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 transformed into a sea of 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. I liked to imagine they tilted their heads in salute each time we drove by.
Craning my neck out the window, I’d watch until they gradually disappeared around the corner, dissolving one by one into a sea of rainbow colors.
And thus began my love affair with these beautiful flowers.
SO MANY DAHLIAS, 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 perhaps 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. These can range in height from the very tall specimens of my childhood to just under 12 inches. Planting the tubers is easy. Just dig a hole 6 to 8 inches deep and drop them in with the ‘eyes’ facing up. I usually plant three tubers per hole for 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 standard flower 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 while others resemble flowers such as anemones, peonies or orchids.
Waterlily dahlia ‘Pam Howden’
Despite the variety, however, one thing they all have in common are their dazzling colors. Dahlias 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.
Semi-double dahlias have two or more rows of petals surrounding a central disc.
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 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’
Orchid dahlias are open centered flowers with just one row of ray florets surrounding a disc. The petals are often overlapping and curled for most of their length.
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 ‘Mary Eveline’ plum red petals with white ‘collar’
Ball and Pompon dahlias are ball-shaped and feature double flowers with rounded or blunt tipped florets. Pompons are slightly smaller than ball dahlias, which are known for their perfectly round flower heads.
Orange ball dahlias – notice the slightly flattened shape
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’
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 are considered double flowers and reach an average height of around 40 inches.
Orange cactus dahlia
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 need to winter indoors in a cool, but not cold, space
Considered hardy outdoors in USDA zones 8 to 10, dahlias are considered tender in my neck of the woods (Zone 6.) Once they’re done flowering in the fall (or right after the first frost), I dig them up, label them and store them in a dry spot in the basement.
Want to learn more? Visit Longwood Gardens’ annual dahlia show, held each year in Kennett Square, Pennsylvania. Looking for a great place to buy tubers? Check out the beauties at Eden Brothers, one of my favorite online sources.