Growing Instructions For Dahlias

Flowering period: July - October
Planting depth to base of bulbs: 5 - 7 cm above the top of the tuber
Spacing between bulbs: depends on the type of dahlia (average is 5-7 per m²

Type of bulb: tuberous root
Light requirements: sunny (at least for a couple of hours AM sun)
Landscape uses: border, and depending on the type also in pots and containers. Also as cut flowers from the garden.

Dahlias are absolutely perfect for borders. Here, often combined with annual plants, most of them also excel due to their extremely long flowering period. The result? A cheerful rainbow of colours. Dahlias can also be assigned a leading role in the perennial border, the tall varieties fitting in perfectly in the back row. While making their presence known when the summer-flowering plants are in full bloom, they are still going strong with the last autumn-flowering asters are in bloom. Borders featuring spring-flowering plants simply cannot do without dahlias.

Critics sometimes find dahlias a bit too massive, and sometimes they are even said to be too splashy for the border. These remarks, however, are usually aimed at the extremely large-flowering Decorative, Cactus-flowered, and Semi-cactus cultivars. They certainly do not apply to the Peony-flowered varieties such as ‘Bishop of Llandaff’ or its successor ‘Fascination’, nor to the uniquely coloured Anemone-flowered or Collerette dahlias. Another dahlia cultivar that fits in beautifully with all kinds of perennial plants, especially blue-flowering ones, is ‘Giraffe’.

When selecting plants for bedding purposes, the colour effect they produce is the most important factor. What’s more, plants for bedding must be uniform in size, sturdy, and brightly coloured. Finally, they must not grow too tall. When considering all these characteristics, plants from the newly developed Dahlinova, Dahlstar, Gallery and Impression dahlia series would be perfect for bedding purposes. Other dahlias exceptionally suitable for bedding would be the Top-Mix and Mignon dahlias and other naturally low-growing cultivars such as ‘Berliner Kleene’, ‘München’, ‘Red Pygmy’ and ‘Witten’. An advantage offered by the newer varieties, as well as some of the older ones, is their wide variety of colours and their floriferousness. Dahlias from the Gallery Series in particular feature flowers that remain attractive for a longer time on the plant, meaning that less maintenance is necessary to produce an effective, long flowering period.

Dahlias are ideal for growing in pots and containers. Especially good for this purpose are the Mignon, Top-Mix, Dahlietta, Dahlstar, Dahlinova, and Gallery dahlias, as well as all other low-growing dahlias with compact habits. Experimenting with somewhat taller dahlias in larger containers or tubs is also recommended. ‘Bishop of Llandaff’, for example, has been grown in containers for years with good results and is showing increasing popularity as a tub plant. The bright colours so typical of dahlias fit in well with other annual plants, but one can also choose to let dahlias play the leading role by combining them with less conspicuous plants such as Summer cypress (Kochia scoparia), grey-leaved Senecio cineraria or Helichrysum petiolare, or the subtle Polygonum capitatum that can be used at (and tumbling over) the edge of the container.

Provide proper drainage for the pots. Holes in the bottom and low on the sides, as well as adding a layer of clay granules to the bottom of the pot or container, are musts. Use ordinary potting soil available from any garden center

Courtesy of the International Flower Bulb Center (