Dahlias – Varieties, Planting and Care

The genus Dahlia is part of the Aster family and has 42 varieties that have become the basis for 15,000 hybrid varieties with increased ornamental value. They are popular with growers for their variety and ability to find the right one for their climate and wishes (color, height, decorative qualities).

Dahlias, bright and lush flowers, invariably conjure up associations with childhood, school, the coolness of autumn, and the sadness of a summer gone by. Generations of gardeners have loved these luxurious plants for their colorful blossoms, diversity of varieties, long flowering time, and unpretentiousness.

Historical Background

Dahlia is native to Mexico but is cultivated in almost every inhabited area on the planet. The genus was first described in 1791 by Antonio Cavanilles, who named it Dahlia. Later, in 1803, when the flowers were introduced into Russia, the local botanist Carl Wildenov renamed them, Dahlia. The genus was named after Johann Georgi, the famous St Petersburg academic and researcher in geography and botany.

Dahlia: Botanical Description

Despite the variety of varieties and species with differences, a standard botanical description is relevant to all members of the genus. Dahlias are tuberous plants with a yearly cycle of development. Individual hybrids are often used as annuals in flowerbeds. The botanical characteristics are described below.

  • The root system is tuberous and vertical, with thin, cord-shaped offshoots. The tubers are cylindrical, narrowed in the lower part.
  • The stems are strong, smooth, and hollow inside. Some cultivars may have stems exceeding 2-2.5 m in height. Wild cultivars found in the Americas can grow to 5-6 m but are not cultivated.
  • The leaves are paired, sessile, and simple, with a pointed end and large denticles along the edges. The leaves are most often pinnate, and in some cultivars, they are solitary.
  • The inflorescences are large, solitary baskets wrapped in multi-layered green leaves, consisting of marginal lingual and median, tubular flowers.

The varieties differ in color, stem height, flowering time, and other parameters. The most common variety grown in Europe is Variable Dahlia. This species is the ancestor of numerous varieties and hybrids cultivated in gardens and flower beds.

Dahlia Blooms

Dahlias are ranked as typical baskets in terms of the structure of their inflorescences, but their shape, in most cases, does not resemble the reference 'daisy.' The inflorescences are surrounded by a beautiful, multi-row, cup-shaped wrapper with lanceolate green leaves fused at the base. The center flowers of all the wild dahlias are tubular, and the edge flowers are lingual; in the garden varieties, some or all of the tubular flowers are transformed into lingual ones, which makes them look more majestic.

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This description alone does not cover the variety of blooms they produce. The reed flowers of dahlias can take on many different shapes, not to mention varying sizes and colors, resulting in a very abundant variety of simple, semi-maximum and tumescent flower forms, from the classic to ball, pompom, peony, aster, anemone, and even cactus flower types.

The color palette of the tubular flowers is limited to a yellow-red-brown range. The reed petals can be colored in many different shades, from white to pink, lilac, red, blue, and mauve, to the much rarer and warmer colors of the yellow-brown spectrum.

All of the hues represented in the dahlia color can be classified as autumnal. Among them, you can find perfect speckles and cherry, beet and burgundy, scarlet and scarlet-black, golden and sunny yellow, brick and ochre, and of course, all shades of lilac, from lavender to purple-pink. Variations in watercolor color transitions, contrasting spots, and two-color combinations only add to the richness of the color palette of this amazing tuberous plant.

The scent of dahlias is rarely praised. Specific, bitter, and so autumnal, it is not found in all varieties. Gentle and spicy, the dahlia scent is more perceptible in bouquets than in the garden.

After flowering, the seeds of the fruit are set. They hide up to 140 seeds. In more enormous, dahlias look good in the garden but usually, in regions with harsh winters, it is impossible to wait for the seeds to ripen due to digging them up.

Classification of Dahlias

Although over forty species in the genus Dahlia, wild, or species-dahlia are not used in garden culture, native to the mountains of Central America, they do not resemble the spectacular and variegated dahlia we are accustomed to.

The basic international classification of dahlias is straightforward, in contrast to the more than 15 000 varieties of dahlia that can be found worldwide. It considers the main characteristics of flowering – the structure of the inflorescence, or more precisely, the shape of the reed flowers and the degree of fimbriation of the inflorescence.

There are 14 groups of dahlias based on the international classification:

  • Single-row dahlias (internationally known as Sin, Single-flowered dahlias) are modest cultivars with simple inflorescences that have lobed flowers in one or two rows around the outer circumference and tubular flowers in the center and basket.
  • Anemone-shaped dahlias (internationally known as Anem, Anemone-flowered dahlias) are hemispherical dahlias whose inflorescences are shaped like anemones. One or two rows of large, oval, lobed flowers flank a lush center of long tubular flowers in the center.
  • Collared dahlia cultivars (internationally known as Col, Collerette dahlias) are cultivars with two rows of lingual flowers, consisting of a broad, large-petaled outer one and a narrow, differently colored or curled inner circle, which seem to encircle the center of the tubular flowers.
  • Nymphaea cultivars (international designation – WL, Waterlily dahlia) are majestic dahlia varieties whose flower shapes resemble lotuses or water lilies due to the oval, partly concave, arranged in separate closed circles of petals.
  • Decorative dahlias are all varieties with multiple, concentric-circle, pointed, bent, or concave very wide petals in a flat or nearly flat inflorescence.
  • Ball-shaped varieties (international designation Ba, Ball dahlias) are almost perfectly spherical or hemispherical inflorescences formed by numerous, curled at the bottom into a tube, rounded lingual flowers at the top.
  • Pompon dahlias are small-flowered, up to 7 cm in diameter, with an ideal spherical shape and concentric arrangement of oval, tubularly-curled petals.
  • Cactus dahlias (international designation C, Cactus dahlias) are varieties with tubular, semi-curled, or longer-lobed petals. In domestic classifications, the straight cactus cultivars with full-length rolled petals and the chrysanthemum-shaped cactus cultivars with curved, arching petals are distinguished separately.
  • Semi-cactus cultivars – differ from cactus cultivars in having only slightly curled petals on the edges (not more than half the length).
  • Hybrid dahlia varieties (internationally known as Miscellaneous, Miscellaneous dahlias) cannot be characteristically identified in other dahlias groups.
  • Fimbriated dahlias are varieties with split-toothed edges of the lobed petals, which create a fuzzy or lacy effect.
  • The Star or Single Orchid varieties (internationally known as SinO, Single Orchid (Star dahlias) are simple, non-flowered dahlias with one row of lobed flowers, evenly spaced and partly twisted.
  • Double Orchid Dahlias are a large orchid dahlia variety with no center visible under the outwardly or inwardly curled, narrow-lanceolate lanceolate flowers.
  • Peony-flowered dahlias (internationally known as P, Peony-flowered dahlias) are beautiful and large semi-major dahlias whose flowers consist of 3 to 4 rows of broad, lobed petals around a disk of tubular flowers. The inflorescences are flat and elegant.

Using Dahlias in Garden

Dahlias are exclusively seasonal plants for all countries with harsh winters, including those in the Midlands. They do not overwinter in the open air and must be kept out of the ground yearly. But this does not restrict their range of use at all. The splendid variety of dahlias allows you to include them in almost any arrangement.

They are suitable for country style, romance, periodic trends, modern trends, and even modern. There is only one limitation – the need to calculate the color scheme of ensembles carefully. Dahlias could be better in colorful, harsh combinations but in harmonious color combinations. Dahlias can be used as a solo plant, in monographs, and in mixed groupings of all kinds. In combination with perennials and other seasonal accents, in groups with decorative bushes and trees and for filling empty spaces. Dahlias are also indispensable as a temporary camouflage for utility lines and buildings.

Dahlias look great in mixed-type mix borders if placed as seasonal accents and introduced in places designated for summer and dugout crops. But dahlias are often planted in classic groups, masses, and free-standing arrangements. A single flower bed of dahlias or a spot on the lawn is a garden classic.

Large and abundant varieties can also be arranged as single shrubs. But the most interesting effects are achieved by mixing varieties with different heights, colors, and shapes of inflorescences. A strict ranking from low to medium and high varieties is mandatory for compositions with dahlias.

Common varieties are associated with border planting, colorful ribbons near paths, or on narrow strips of soil. But both medium and tall dahlia varieties can create masking or dividing lines. Wide low-growing dahlia varieties are well suited to pot culture. Even medium to taller cultivars can be planted in large pots and tubs to decorate a patio or seating area, accentuate a path, and the entrance to a house. Dahlias require deep and spacious containers. Taking care of them is not unlike growing any other potted tuberous plants. Except for the excellent opportunity to change the timing of flowering: planting on a bunting, an early start allows you to decorate
gardens with dahlias in bloom even in late spring, stretching the season of the favorite autumn queen for the whole garden year.

Dahlias are a valuable cutting crop. Gorgeous, often terry varieties are a regular feature in autumn bouquets. The main criterion for cutting is the length and sturdiness of the stems. Dahlias can last a long time in a cut, but you can cut them in full bloom and the early morning hours.

Planting and Care

The most common dahlia species are unpretentious and undemanding. But knowing the basics will help to maximize their decorative potential. How to grow dahlias – Here are the basic rules.

  • Dahlias are more commonly planted as tubers and sprouts. Germinate the tubers in a well-lit room for about 1 month before planting outdoors.
  • Annual hybrid cultivars are grown from seed by preparing seedlings and sending them outdoors in May.
  • The site for dahlia should be in an open area with good sunshine.
  • The soil should be loose and slightly acidic or neutral.
  • Dahlias do not tolerate over-watering but should be watered regularly, once or twice a week.
  • Care is standard: hoeing, weeding, and disease prevention.
  • Fertilizers are applied before planting (organics) and monthly (compound fertilizers).

In regions with a harsh climate, perennial dahlias are dug out for the winter and dried, and the tubers are left in the cellar for storage. In general, the process of growing dahlias is challenging. All that is required is a good environment and timely cultivation.


Lush dahlia bushes covered in bright, large flowers are an eye-catcher. They bloom uninterrupted throughout the summer and autumn, and only the harsh breath of the coming frost destroys their charm.

Dahlias are perennial tubers, with their annual die-off above the ground and perennial solid tubers that have a supply of nutrients for initial bud growth. They belong to the Compositae family. They are native to North America. There are now over 10,000 varieties of dahlia.

With so many different shapes and colors, dahlias can fit into any bed, mix-boarder, container, balcony, or patio. The taller varieties are suitable as a striking backdrop or luxurious accent on the lawn.


What does Dahlia mean?

Dahlia is a symbol of perseverance and determination. Dignity. The flower's exquisite and majestic appearance is associated with high morals, self-control, and nobility in both men and women.

What do dahlias like?

Dahlias like quiet, sunny locations with light shade at midday and well protected from wind and draughts. But if they get less than 6 hours of sunlight a day, they may not produce buds. Dahlias prefer loose, fertile soil with a neutral reaction.

How do dahlias grow?

Dahlias will grow well even in shaded areas if the soil is fertile and neutral. In acidic soils, they will simply die. They can't tolerate low groundwater and rainwater, so they should be planted in beds at least 35 cm high with a burial depth of 15 cm.