Maintenance is necessary to ensure the initial establishment of the green roof’s planting. It is recommended that the installing contractor retains responsibility for the roof's maintenance during the important early stages of establishment and preferably beyond.
Extensive Green Roofs
Extensive green roofs should be maintained by an appropriate workforce at least twice per year. Maintenance actions typically include:
- Removal of undesirable native plant species
- Annual application of a slow‐release fertiliser to increase the substrate's nutrient supply
- Inspection of outlets for blockages
- Replace any localised failed plant material
- Remove any vegetation from non-vegetated areas such as fire breaks or ballasted perimeter areas.
Note that irrigation is not typically required for most extensive roofs, however periodic irrigation may be required, for example, in times of prolonged drought.
General roof maintenance should include checking outlets for blockages and removing any vegetation from fire barriers. However, Biodiverse Maintenance Programmes must be carefully planned and documented within a Habitat Management Plan at design stage to ensure compliance with the roof's biodiversity hypothesis:
- No materials (e.g. wind‐blown species, dead planting) should be removed if they may adversely affect the roof's biodiversity potential.
- Fertilisation is not generally required. Biodiverse substrates are typically specified to be low in nutrients to minimise growth of non‐native species.
Intensive Green Roofs
Intensive green roofs can include a wide range of plant types and species and the maintenance programme should be configured accordingly. However, the following regular maintenance actions are typical:
- Seasonal assessment plan
- Identification of any pest/diseases/actions
- Removal of undesirable plant species
- Replacement of any failed plant material
- Application of nutrients, where necessary
- Rejuvenating and corrective pruning of shrubs and trees
- Mowing, spiking and fertilising of grassed areas
- Upkeep of paved/gravel areas
- Inspection of outlets and irrigation systems