Helianthus decapetalus Soleil d'Or

Helianthus decapetalus 'Soleil d'Or', also known as perennial sunflower, is an old variety of medium-sized Helianthus with medium-sized, double, golden yellow flowers. This herbaceous perennial forms a rosette of deciduous, dark green, oval leaves from its rhizomatous stump, which rise up into rigid and ramified stems to form a dense and wide bush. The abundant head-shaped flowers crown its beautiful upright tuft throughout the autumn season, when many plants are fading. The bright hues of its flowering harmonize perfectly with the fiery colours of autumn foliage. Use this ultra hardy and easy to grow perennial to create flowering screens, low-maintenance in the background of a field of plants. Not demanding, it thrives in ordinary and fresh soil in full sun or partial shade.

Helianthus decapetalus, or Ten-petal Sunflower, belongs to the Asteraceae family. This large perennial is native to the central and southeastern United States. The 'Soleil d'Or' variety reaches a height of 1.20m (4ft) with a spread of 80cm (32in). The overall plant forms a bouquet of solid, glabrous stems at the base, bristly and rough towards the top, and ramified. The flowering occurs from September to November. The heads appear at the top of the stems in large numbers, like fully double and round daisies, measuring 5 to 8cm (2 to 3in) in diameter. The deciduous leaves are dark green, lanceolate to obovate, hairy underneath, measuring 10 to 20cm (4 to 8in) long and toothed. They are distributed up to the top of the stems.

The great interest of perennial sunflowers lies in their late flowering and excellent adaptation to heavy, clayey, moist, even limestone soils.  Helianthus decapetalus 'Soleil d'Or' is an excellent and long-lasting perennial. Vigorous, it is perfect for the background of a border or for mixed borders. It is a plant with a rustic appearance that blends well in slightly wild areas of the garden, alongside Cosmos, sainfoin, large Scabious, and trailing Liches for example. Another idea for association, with equally easy plants: Vernonia noveboracensis, Eupatorium fistulosum, Andropogon virginicus, Muhlenbergia capillaris. Its tall stature allows it to be placed in front of bushes (deciduous Euonymus, Spirea, Hydrangea quercifolia, Cotinus..) that will serve as natural supports, while blending their autumn colours with its sunny flowering.