Project constraints
Over and above the aesthetic aspects (“lush” or “bushy” canopy, varied or uniform colors, wild or well-manicured appearance), the choice of plant palette for the green roof also depends on the characteristics of the greening project.
1- Climate constraints
The plants selected in the plant palette must be adapted to the climatic constraints of the project. For example: geographical location, local climate (very cold winters, excess water, drought), exposure to sun and wind…
2- Roof pitch
The choice of plants and their installation must be adapted to the slope of the roof. To limit the risk of plant erosion, perennials and ground cover are generally preferred for sloping projects.
3- The load accepted by the roof support
The maximum load accepted by the substrate will determine the thickness and weight of the green roof complex: the greater the load accepted, the thicker the substrate layer can be, and the wider the plant palette. A distinction is therefore made between plant coverings for extensive green roofs (the load accepted by the substrate is low) and plant coverings for semi-intensive to intensive green roofs (the load accepted by the substrate is higher).
4- Project visibility
If it’s visible from the outside or close to an area accessible to the public, a roof will be planted with more decorative plants (evergreen and colorful foliage, long-blooming species), with aesthetics often taking precedence. A green roof with little or no public access has different objectives: contributing to biodiversity, bringing green back into the city, helping to clean up pollution, etc. In this case, the choice of plants is much wider. The choice of plants is therefore wider.
5- Desired level of maintenance
Certain plants reduce the invasion of wild or undesirable weeds on the roof, thus limiting annual maintenance of the vegetation. The desired level of watering also has an impact on the choice of species making up the plant layer.
Sedums, a plant family at the heart of extensive roof greening.
Rooftop living conditions are very demanding: extreme temperatures, wind, long periods of drought… The implementation of vegetation on a very limited substrate height requires particularly resistant plants. Sedums are particularly well-suited to these conditions. As fat plants, they can withstand long dry spells before starting to grow again. With varying heights, sedum varieties can be mixed and matched to create an aesthetically pleasing, even plant cover over time.
Predefined plant cover Le Prieuré
LE PRIEURE’s range of plant coverings offers diversified vegetation to meet all requirements (uniform, flowering, varied cover) and all constraints (shaded roofs, exposure to wind, slopes, mountain climates, etc.) of a green roof project.
Since 2024, LE PRIEURE has obtained the Végétal Local label for part of its production, enabling native plants to be planted on roofs in the Paris basin.
