How To Maintain Green Roofs

Green roofs are living structures and as such need attention throughout their lifespan. Some vegetation types such a sedum are planted as they require less maintenance than grass roofs for example. However, regular attention to soil moisture and feed levels as well as the removal of weeds is essential to maintain optimum performance.

Extensive green roofs including M-Tray® modular roofs

Spring schedule

• Remove weeds by hand pulling only
• Apply Wallbarn slow release granular fertiliser at a rate of 50gsm
• Clear debris from drainage outlets
• Generally inspect vegetation area and monitor poor growth areas
• Insert cuttings from good growth areas into bad growth areas
• Check irrigation system (if applicable) and replace timer batteries

Autumn schedule

• Remove weeds by hand pulling only
• Clear debris from drainage outlets
• Generally inspect vegetation area and monitor poor growth areas
• Cut back dead stalks or dying vegetation
• Insert cuttings from good growth areas into bad growth areas
• Check irrigation system (if applicable) and drain down

General points

Sedum

Sedum is a unique plant in that its metabolism is reversed from most other plants. Sedum closes its stamen during the day which contributes to it being more efficient at conserving water. Sedum leaves will change their colour at times throughout the year and will often take on a russet colour during, drought, strong wind and frost. This is normal and they will revert to their normal green hue over time. Should the stems and leaves start to ‘shrivel’ back then this is a sign of a problem and in the main lack of water. Irrigation must be applied to reverse this and the levels of water checked for several weeks until the sedum has recovered.

Wildflowers

Wildflowers are weeds and weeds are wildflowers and so care must be taken during maintenance NOT to pull out healthy and desired plants. Wildflowers by their nature thrive on poor soils where there is little competition however they are more vulnerable to drought. Drying of stems and leaves will be seen through hot dry periods and although irrigation can be applied it is not a requirement as the ‘stressed’ plants will flower.

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