Trillium grandiflorum

Trillium grandiflorum is one of the easiest American botanical trilliums to acclimatise in our gardens, in cool understory areas. In spring, it bears beautiful and long-lasting pure white flowers, which often turn pink with age. They arch over a trio of dark green leaves. This iconic hardy perennial from northeastern America is perfect for shade. Slow to establish even in favourable conditions but very resistant to cold, it gradually colonises thick undergrowth, protected from the sun's bite. The sight of young white flowers mixed with older flowers that become increasingly pink creates a magical spectacle in early spring.

Trillium grandiflorum belongs to the Melanthiaceae family. This rhizomatous herbaceous perennial is native to northern and eastern North America, from southern Ontario and Quebec to New England, Michigan, Minnesota, and Wisconsin. It is a characteristic species of somewhat dry maple forests in summer, where it carpets the ground. It is also found on damp rocky banks. It has received the Royal Horticultural Society Award of Garden Merit for its ornamental qualities and performance in the garden.

Its growth starts in spring. It forms a clump 25 to 30cm (10 to 12in) tall, with a minimum spread of 35cm (14in). It slowly expands in width through its rhizomes without becoming invasive, eventually forming large colonies. Initially, it produces only a few leaves and one or two flowers, but it spreads once it reaches a certain size. Flowering occurs in March-April, before deciduous trees develop their leaves. The 5 to 8cm (2 to 3in) diameter flowers have a corolla with 3 deeply veined and slightly curled pure white petals that are often tinged with pink as the flower ages. They are carried at the end of a stem emerging from the heart of 3 ovate, veined leaves, in a very dark green shade. Each flower lasts 2 to 3 weeks before withering. The flowering is followed by the formation of red berries that turn black when ripe. Their seeds are dispersed by ants. This slow-to-establish plant can live for several decades.

Trillium grandiflorum is primarily a plant of deciduous understory, in cool and moist environments. It will look wonderful with ferns, cyclamens, helxines, perennial geraniums, arisaemas, or Solomon's seals. It will have a beautiful effect in a wild garden, planted in shady borders, or under deciduous trees and shrubs. Its long rhizomes also help to stabilise the soil of cool and shaded banks.

In Canada, trilliums colonise forests in the same way as bluebells. However, they are demanding plants that should only be grown by experienced gardeners. Patience is required: trilliums take a long time to establish and can sometimes be capricious.