Dahlia Osirium

Dahlia 'Osirium' brings something very new to the Dahlias of the Decorative group, both in terms of its unprecedented bicolour hue of its flowering and its curiously cut light green foliage. Its well-double flowers are modest in size but don't go unnoticed, with petals slightly tubular in a dark garnet purple revealing here and there a silvery white reverse. It blooms for a long time, from summer to autumn, on a beautiful and beautifully leafy clump. A star plant of curate gardens, 'Osirium' pairs well with shades of pink, mauve, white, and deep red, as if arbitrating the more subdued flowerings in the background of perennial beds. Its beautiful flowers are very long-lasting in a vase.

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Dahlias are tuberous plants of the large aster family, originally native to the high plateaus of Mexico. Currently, the some 25,000 horticultural varieties obtained by humans have invaded, to our great pleasure, gardens worldwide. Dahlias are classified according to the shape of their flowers. 'Osirium', introduced in 2005, belongs to the category of Decorative Dahlias. In this group, the coloured ligules of the head are regularly arranged in a spiral, they can be curved towards the stem or fringed, for example. In this variety, the inflorescences in heads are about 10 cm (4in) in diameter and their ligules or petals are slightly curled, lanceolate in appearance towards the heart of the flower. Their colour is striking: a garnet red or burgundy on top, they show an almost white reverse. The centre of the head is occupied by ligules in more mauve tones. The flowering takes place from July to October. The plant will reach 1.20 m (4ft) in height, and 60 cm (0 and 24in) in width, with a bushy and erect habit. The foliage of Osirium is particularly cut: the leaves are opposite, pinnately divided into many leaflets, which form very denticulate lobes. The leaves are light green and the flower stems are tinted with purple. As with all Dahlias, the highly branched stems are hollow.

To promote flowering and extend the flowering period, take care to remove faded flowers. Even better, regularly create attractive colourful bouquets by combining various varieties. The tall stature of this variety makes it suitable for the back of perennial beds, of course, to structure a composition of flowering shrubs and lower perennials. The blooming of summer and autumn asters is perfect as an accompaniment to that of Dahlias, they occur simultaneously, as well as that of perennial salvias or cannas, for example. Beautiful scenes can be composed at the end of the season by combining Osirium flowers with Japanese anemones, shrubby salvias... Also consider grasses (Miscanthus saccharifolius, Stipa arundinacea, Eragrostis trichodes) which take on beautiful colours in autumn.

A star plant of curate gardens, Dahlias are undoubtedly beautiful flowers, they are impeccable in a flower bed but can also enhance a vegetable garden. In Mexico, this tuberous plant was first cultivated as a root vegetable for consumption. Its poor taste quickly relegated it to the rank of ornamental plant. Since then, interest in their beautiful exuberance has never waned.