Royal Horticultural Society: Establishment and Management of Prairie Grasses (Charcoal mulch)

Tom Miles

Establishment and Management of Prairie Grasses
Royal Horticultural Society Research, UK, 2007

Establishment of North American prairie grasses by field sowing was investigated at the Royal Horticultural Society Garden at Wisley. This experiment is part of a larger programme of work to investigate the use of North American prairie wildflowers and grasses as a style of planting in gardens and parks in Britain, which is a modern, informal and low maintenance. It is particularly appropriate for amenity planting.

Grass species

Schizachyrium scoparium Prairie grasses with high horticultural potential include little bluestem, (Schizachyrium scoparium); indian grass, (Sorghastrum nutans) and prairie dropseed, (Sporobolus heterolepis). All three species are widely used in contemporary garden design in Europe and North America. They also have a considerable tolerance of drought, which can be an important characteristic on sandy soils in southern England.

The Schizachyrium population used in the study has blue grey foliage in summer, which turns red in autumn, with this colour being retained throughout the winter. Sorghastrum is a taller grass with attractive bronze flowers in September, and apricot autumn leaf colour. Sporobolus is the slowest growing of the three but has brilliant green, narrow leaves and forms a fountain-like tussock. The leaves turn orange in autumn.

Germination of seed

Our goal was to see whether it was possible to establish these grasses by sowing seed in situ rather than transplanting. This is potentially an economically attractive technique when large areas of grasses are required as part of a naturalistic planting scheme.

All three of the species used in this study are categorised as warm season (C4) grasses; they typically require relatively high soil temperatures (above 20