Green roofs require little maintenance, but this is essential to ensure the longevity of the vegetation. With regular care, you’ll be able to achieve at least 80% vegetation cover in no time, and above all, maintain this level over time.

It is strongly recommended to formalize this maintenance with a contract with a specialized company, as soon as the project is completed. Le Prieuré offers maintenance contracts tailored to each project, covering roof vegetation and sterile areas. The waterproofing must also be regularly maintained by the waterproofing contractor (as described in DTU series 43).

There are three distinct phases: completion, reinforcement and routine maintenance. The types of maintenance operations depend on the construction period, the revegetation technique used and the type of plant cover selected.

The completion period

This is the period between installation of the green roofing system and acceptance of the work. Its duration varies according to site coordination conditions.

During the completion period, maintenance is the responsibility of the project owner. Once the work has been completed, maintenance of the green roof is the responsibility of the Owner. Once the green roofing system has been installed, the Professional Rules distinguish between two maintenance periods: the reinforcement period and the routine maintenance period.

Reinforcement period

This is the period of maintenance required after the system has been installed on the roof, to achieve a vegetation cover rate of at least 80%. The length of the maintenance period and the minimum frequency of intervention vary according to how the vegetation is installed.

It is minimized for pre-cultivated systems: non-existent for the HYDROPACK® tray (plants are already installed and rooted), it can reach 3 to 6 months for LP Mat pre-cultivated mats (time needed for plants to anchor themselves completely in the entire thickness of the substrate layer).

In the case of micro-core or bucket planting (LP MOTTE and LP GODET) or fragment sowing (LP FRAGMENT), a consolidation phase of 1 to 3 years is required to achieve a minimum coverage rate of 80%. During this period, regular maintenance is essential. Watering is particularly important for the rooting of sedum fragments. You need to monitor the plant’s water requirements and water as soon as necessary, depending on climatic conditions and the plant’s speed of establishment (deep rooting in the substrate).

The main maintenance operations during the reinforcement phase :

  • removal of wind-borne waste from vegetated surfaces and barren areas
  • reinstatement of the cultivation layer in the event of displacement by wind or rain
  • manual weeding of unwanted vegetation
  • watering according to weather conditions, especially for vegetation solutions using fragmented seedlings
  • fertilization
  • in the event of partial or total failure to recover: additional sowing (sedum seeds or fragments), planting (plugs or cups), or installation of pre-cultivated elements.

Once the reinforcement period is over, and regardless of the vegetation system chosen, routine maintenance remains essential.

Routine maintenance

This period begins as soon as the vegetation cover reaches 80% and the plants are well rooted. The aim is to maintain this level at a minimum of 80%.

For extensive greening solutions: 1 to 2 passes / year.

Routine maintenance begins in the first year for pre-cultivated systems (e.g. HYDROPACK® tray, LP Mat sedum mat). For non-pre-cultivated systems, it is necessary to wait until the end of the reinforcement period (1 to 3 years).

For semi-intensive planting solutions: 3 to 4 passes per year, depending on the type of plants installed. Some plants (shrubs and grasses) require several pruning or cleaning operations per year.

The main maintenance operations during the routine maintenance phase :

  • Manual weeding of undesirable species that can damage waterproofing (woody plants, shrubs) and unsightly weeds or weeds that smother sedums.
  • Removal of leaves (which can smother vegetation and block storm drains).
  • Clearance (vegetation, garbage, etc.) around rainwater drains and on the perimeter strip.
  • Monitoring and detection of any other problems (bird or rodent damage, specific diseases, etc.).
  • Check drainage condition.
  • Apply suitable fertilizer every year (especially on sloping roofs)
  • Mowing or pruning of species with stronger vegetative growth
  • Irrigation system maintenance

Wherever the project is located, it’s essential to have a watering point on the roof. It must be easy to use for punctual watering, whether for plant installation or during dry periods. Certain project locations and/or roof slopes also require the installation of an automatic watering system. This will preserve the canopy during the summer months.

The maintenance of a green roof can cover several aspects:

  • routine maintenance of your vegetation system. Le Prieuré offers a maintenance contract tailored to your project and your vegetation complex. Le Prieuré’s maintenance team is made up of qualified and competent personnel working both on the roof and in the nursery.
  • diagnosis of your green roof
  • renovation of your vegetation system