The author’s experience suggests that, as a result of diminished competition, herbaceous plants are more readily established by planting in these types of vegetation, for example,
Creating prairie vegetation at the Eden Project by, first, planting then immediately afterwards sowing a prairie mix over the top: (a) the site immediately after the completion of planting and sowing in March; and
(b) the same site two growing seasons later in August
The same principle applied to a garden. May to June flowering herbaceous plants, such as Iris sibirica and Thalictrum aquilegifolium flower above a sown sward of late summer flowering prairie plants. By July, the former will have finished flowering and will be hidden by the 1 m plus prairie plants
randomly at the specified intervals. The timing of establishment is typically determined by the needs of the sowing, as with container-grown stock, the planting date is much more flexible. Over-sowing previously planted stock is well suited to situations where relatively weed-free subsoil, sand mulching or abundant skilled labour is available. The author has used this technique to successfully establish prairie vegetation on a number of sites, including the Eden Project in Cornwall (Figures 6.18 and 6.19).