The influence of plant species number on productivity, ground coverage and floral performance in grass-free lawns

Abstract

The grass-free lawn is a novel development in modern ornamental horticulture where the traditional monoculture of grass is replaced by a variety of mowing-tolerant clonal forbs. It brings floral aesthetics and a diverse species approach to the use of lawn space. How the number of constituent forb species affects the aesthetic and structural performance of grass-free lawns was investigated using grass-free lawns composed of four, six and twelve British native clonal perennial forb species. Lawn productivity was seen to increase with increasing species number, but the relationship was not linear. Plant cover was dynamic in all lawn types, varied between years and was not representative of individual species’ floral performance. The behaviour of component species common to all lawns suggested that lawns with 12 species show greater structural stability than lawns with lower species number. Visual performance in lawns with the greatest species number was lower than in lawns with fewer species, with increasing variety in floral size and individual species floral productivity, leading to a trade-off between diversity and floral performance. Individual species were seen to have different aesthetic functions in grass-free lawns by providing flowers, ground coverage or both.