Apart from aesthetic aspects ("carpeted" or on the other hand "bushy", varied or uniform colours, natural or very well-kept appearance), the choice of a range of plants making up a green roof also depends on the characteristics of the planting project.
The constraints of the planting project
- Climatic constraints Plants selected from the range of available species must be suited to the project's climatic constraints. For example: geographical location, local climate (very cold winter, excessive rain, drought), exposure to the sun and the wind, etc.
- The pitch of the roof The choice of plants and the way they are planted must be suitable for the pitch of the roof. In order to limit the risk of erosion, preference is generally given to perennial plants and those provide a large amount of ground cover.
- The load capacity of the roof The maximum load supported by the load-bearing component will determine the thickness and weight of the vegetating system: the greater the supported load, the thicker the growing medium, and the more extensive the range of suitable plants. This means we can distinguish between plants for extensive green roofs (the load supported by the load-bearing component is limited) and plants for semi-intensive green roofs (the load supported by the load-bearing component is higher).
- Project visibility If it is visible from outside or is close to an area accessible to the public, a roof will be planted using more decorative plants (long-lasting and colourful foliage, long-flowering species), with aesthetics often taking precedence. A green roof which is barely visible to the public, or not at all, has different objectives: to contribute to biodiversity, to bring back green into the city, decontamination, etc. The choice of plants in these projects is much wider.
- The desired level of maintenance Certain plants restrict the invasion of weeds or undesirable plants on the roof, which minimizes annual plant maintenance. The desired frequency of watering also affects the choice of species constituting the plant layer.
Sedums, a family of plants vital to extensive green roofs. Living conditions on roofs are very demanding: extreme temperatures, wind, long dry period, etc. Using plant cover on a very shallow depth of growing medium requires exceptionally resistant plants. Sedums are particularly suitable for this. As they are succulents they can endure long, dry periods, before they start to grow again. Of different heights, the varieties of sedum are mixed in order to obtain an attractive yet uniform plant cover on the roof.The Vegetal i.D. range of plants
The wide range of suitable Vegetal i.D.® plants offers diverse planting meeting every requirement (uniform, floral, varied cover) and all the constraints (shaded roof, exposure to wind, pitch, etc.) of an extensive or semi-intensive green roofing project.
Examples of Vegetal iD roofs (from left to right): i.D. SEDUM, i.D. MIX-FLORE Prairie, i.D. CREA-PAYSAGE, i.D. CREA-PAYSAGE Patio
The range of plants for an EXTENSIVE green roof
Low-maintenance green roofs: i.D. SEDUM and i.D. MIX-FLORE for very low weight green roofs, that are often barely visible or not visible at all, with minimal water and maintenance requirements. i.D. MIX-FLORE landscaped roofs offer a much wider range of plants (sedums, perennial plants, aromatic plants) than the i.D. SEDUM roof (100% sedums).
Plant ranges for the SEMI-INTENSIVE green roof
- Landscaped plant cover: i.D. CREA-PAYSAGE. For highly visible green roofs supporting an average load, aimed at particularly aesthetic and diverse roof cover, which may require automatic watering and significant maintenance.
- Special biodiversity plant cover: BIODIVERS'i.D.. Ideal for encouraging animal biodiversity in cities, this combination of indigenous plants will give a natural appearance to the green roof.
- Special lawn plant cover: i.D. GAZON. To look green on the roof throughout the year, green roof combining various varieties of grasses for lawns. This kind of roof requires very regular lawn maintenance and watering.
| Roof Membrane |
Type of planting | Thickness of growing medium (cm) | Weight of system (kg/m2) | Plant families |
| i.D. SEDUM | extensive | 4 to 15 | 80 to 180 | Succulent plants, different varieties of ground-covering and clump-forming sedums, suitable for full sunlight or semi-shade |
| i.D. MIX-FLORE Aroma | extensive | 4 to 15 | 80 to 180 | Succulent plants, different varieties of sedum, delosperma, sempervivum, etc. Aromatic and hardy perennial plants |
| i.D. MIX-FLORE Prairie | extensive | 4 to 15 | 80 to 180 | Succulent plants, different varieties of sedum, delosperma, sempervivum,etc. Hardy herbaceous perennials Hardy grasses |
| i.D. CREA-PAYSAGE | semi-intensive | 12 to 30 | 150 to 350 | Succulent plants, herbaceous perennials and hardy shrubs, grasses, flowering shrubs or those with decorative foliage |
| i.D. CREA-PAYSAGE Patio | semi-intensive | 12 to 30 | 150 to 350 | Shade-loving plants providing ground-cover, creeping plants, herbaceous and bushy plants |
| BIODIVERS’i.D. | semi-intensive | 12 to 30 | 150 to 350 | Xerophytic and melliferous plants |
| i.D. GAZON | semi-intensive | 12 to 30 | 150 to 350 | Grasses for lawns |
Plant family of Vegetal i.D.® roofs
N.B.: certain planting techniques cannot be used with some green roofs.
Range of plant covers and planting techniques
