Vernonia gigantea - Ironweed

Vernonia gigantea is the tallest and most impressive of the Vernonia genus which includes robust perennials closely related to large asters. This magnificent wild vernonia has brilliantly coloured, eye-catching violet-purple flowers in the second half of summer. This proud plant is formed by tall sturdy stems adorned with large leaves, particularly ornamental in rich and moist soil. It thrives in the sun, in the back of a border with large asters, or near water.

Vernonia gigantea belongs to the Asteraceae family. It is a perennial herbaceous plant native to the eastern United States where it can be found in wet ditches along roads, in meadows, and open forests. Anchored by a strong perennial crown, this species can reach heights between 2 and 3 metres (7 and 10 feet), and spread 70-80 cm (28-32in) on the ground. The size of the plant depends on the fertility of the soil and its moisture content. Its growth is quite fast, but it takes two years to establish. It forms a clump of tall and sturdy, straight, more or less hairy stems ranging from green to purple, bearing large alternate, simple, ovate, dark green leaves up to 23 cm (9in) long. Flowering occurs from August to September-October depending on the climate. At the tips of the stems, small fluffy, violet to magenta-purple pompom flowers appear, gathered in terminal bunches or corymbs. The flowers all open at the same time and are covered in butterflies. The vegetation is deciduous: it emerges from the ground each spring and dies in autumn.

Vernonia gigantea is easy to grow in the sun in consistent, slightly moist soil and blends well with a multitude of plants to form magnificent autumn compositions, especially with large asters and Meadowsweets; on the banks of a pond, it spreads quickly and looks good with joe-pye weeds, Lythrum salicaria, Filipendula rubra 'Venusta', Euphorbia palustris. In a wilder style, in the back of a border, this imposing perennial forms a very successful combination with Rudbeckia maxima, Red Angelica, and tall grasses: Miscanthus 'Malepartus', Panicum, Stipa...