Screening of planting matrices for a green roof in Lanzhou City

To select a suitable substrate ratio for the planting of vegetation on green roofs in Lanzhou City, Anemone rivularis and Hemerocallis fulva ‘Golden Doll’ were used as experimental materials and pastoral soil, peat, vermiculite, and coconut were selected as plant media. Garden soil was used as a control. A pot experiment was designed using the orthogonal test L₉(3⁴) to measure and analyze the physical properties of 10 kinds of vermiculite raw materials using four media, the survival rate of plants in each matrix, the over-summer rate, the over-winter rate, and the plant height, crown, and growth rate at 120 days. The results showed that the No.2, No.3, and No.6 matrices had longer water holding capacities, and the survival rates of A. rivularis and H. fulva ‘Golden Doll’ in the No.3, No.4, No.5, and No.6 matrices were 100%. The over-summer and over-winter rates of A. rivularis and H. fulva ‘Golden Doll’ in the No.5 and No.6 matrices were both 100%. The plant height and crown of A. rivularis and H. fulva ‘Golden Doll’ in the No.3 and No.6 matrices were higher than those in the other matrices, and the growth potential was also good. The results of the range analysis were as follows: the order of the factors regarding their influence on the growth rate of A. rivularis was peat, coconut, pastoral soil, and vermiculite, while the order regarding their influence on H. fulva ‘Golden Doll’ was peat, pastoral soil, coconut, and vermiculite. The best matrix for the growth of A. rivularis and H. fulva ‘Golden Doll’ was the No. 6 substrate, namely the pastoral soil:peat:vermiculite:coconut ratio of 3:6:1:2. Therefore, we recommended that the matrix ratio of No. 6 be used for the green roofs in Lanzhou City.