5 Giant Dahlias to Plant at the Back of a Border

The Dahlia imperialis, a spectacular arborescent flower

The Dahlia imperialis is a giant plant as it can reach heights of up to 3 or 4 metres. This spectacular botanical dahlia has a spreading habit and blooms between September and December. It bears large, elegant flowers in pale lavender pink. Surrounding a yellow-orange centre, petals unfold resembling slightly crumpled scarves. The stems of the Dahlia imperialis, thick and upright, evoke those of bamboo. This plant prefers to be grown in regions with mild winters and temperate conditions, as it is quite frost-sensitive. However, it can withstand short periods of frost down to -5 °C.

Due to its height, the Dahlia imperialis can be planted as a backdrop in an XXL flowerbed. It pairs well with pampas grasses, which are nearly as tall and will add a sense of lightness. You can also add a few plants of Perovskia ‘Silvery Blue’ for a touch of lavender blue, as well as white autumn camellias like the Camellia sasanqua ‘Waterfall White’ to create a magnificent flowerbed with soft tones.

The giant Dahlia 'Pineland's Princess', with its astonishing bristly flowers

Culminating at 80 cm in height, the Giant Dahlia ‘Pineland’s Princess’ boasts flowers known as cactus, as they are beautifully bristly with white petals tipped in dark lilac pink. The flowers are also very large, measuring 17 cm in diameter. They appear from July to October atop upright, hollow, ramified stems, emerging from the tuberous roots of the Dahlia. They bear compound leaves with rounded leaflets. The flower stems are sturdy and fleshy. The Dahlia ‘Pineland’s Princess’ thrives in rich, clayey yet healthy soil, worked deeply. It requires a warm, sunny exposure.

In a border, you can place it in the background alongside other giant Dahlias such as the Giant Dahlia ‘Café au lait’ with its lovely cream colour and stunning flowers measuring 20 cm in diameter. To create a romantic atmosphere, you can add Caucasian scabious with beautiful lavender flowers, as well as Phlox paniculata ‘Famous White’.

The giant Dahlia 'Barbarossa', with very large vermilion flowers.

If you are a fan of large flowers, the Giant Dahlia ‘Barbarossa’ may well captivate you. This plant reaches a height of 1.20 m at ripeness and bears vermilion red flowers measuring 22 cm in diameter. It blooms from July to October. This heirloom variety produces purple stems adorned with beautifully bluish-green leaves. It belongs to the category of decorative dahlias. The flower petals are very wide, slightly curled inwards, and gracefully trailing towards the stem.

To highlight the scarlet red of the Dahlia ‘Barbarossa’, it is best paired in a bed with light flowers in subtle colours. For example, it can be combined with grasses such as Pennisetum x advena ‘Rubrum’ or Stipa ichu. It is also possible to accompany the Dahlia ‘Barbarossa’ with some Cannas, Crocosmias, and amaranths in similar colours to create an exotic atmosphere.

The giant Dahlia 'Lady Liberty', an immaculate whiteness

The Giant Dahlia ‘Lady Liberty’ reaches a height of 1.20 m and produces flowers measuring 22 cm in pure white. It blooms from July to October. Its flowers are double, consisting of a large number of wide petals that elegantly trail towards the stem. They have a particularly stylish and romantic appearance.

In a border, place it at the back and add a few specimens of Hydrangea paniculata ‘Bombshell’, which also reach a height of 1.20 m and are delightful with their pyramidal flowers. To lighten the border, arrange some delicate perennials like Agastache rugosa ‘Alabaster’ and grasses such as the Chinese fountain grass Pennisetum orientale ‘JS Dance With Me’ to create a monochromatic all-white ensemble.

The giant Dahlia 'Islander', for a bed with warm and sunny colours

The Giant Dahlia ‘Islander’ reaches a height of 1.20 m, making it a good candidate for flowering at the back of borders. From July to October, it produces large flowers measuring 20 cm in diameter with wide, flat, and incurved ligules, coloured in soft shades of salmon pink and orange.

Perfect for creating bouquets, use it as a backdrop in a flower bed. It pairs beautifully with Echinacea purpurea, rudbeckias, ‘Sonata White’ cosmos, Solidago rugosa, and helps create a bed and bouquets in warm, sunny colours.

For further reading

• Many other giant Dahlias are to be discovered, such as Cactus Dahlia ‘Erpeler Ley’ or Ornamental Dahlia ‘Motto’.
• Check out our complete range of giant Dahlias to make your choice.
• Also, consult our advice sheet on growing Dahlias as well as the best giant Dahlias.