Performance of six different soilless green roof substrates for the Mediterranean region.

The objectives of this research were to assess the physical properties of six different growing substrate mixtures destined for roof gardens and determine the influence of these substrates on the morphology, physiology, growth and flower quality of pansy (Viola × wittrockiana), Madagascar periwinkle (Catharanthus roseus), and Pavia lily (Longiflorum×Asiatic lilies (Lilium) 'Pavia'). Six green roof growing substrate mixtures (by volume) were used [T1: coarse tuff+fine tuff+cocopeat (5:1:4), T2:coarse tuff+medium tuff+fine tuff+cocopeat (5:5:2:8), T3: medium tuff+fine tuff+cocopeat (5:1:4), T4:medium tuff+fine tuff + peat moss (5:1:4), T5: perlite+medium tuff+fine tuff+cocopeat (5:5:2:8), and T6: lightweight expandable clay aggregates+fine tuff+cocopeat (5:1:4)]. The T6 (LECA-cocopeat) had the lowest weight at field capacity and good aeration and WHC to sustain optimal plant growth.