How do you Maintain a Green Roof?
Well, green roofs are relatively low maintenance entities. Whilst the construction of a green roof can be very labour intensive – particularly if the roof in question needs structural improvements – green roofs don’t need much maintenance. Particularly those of the sedum variety.
And the maintenance required is dependant on the type of living roof and the plants that exist on each. Some may need fertilisers, more careful plant colour and growth monitoring and weeding. So each roof is different, but:
- Clearing debris
- Removing drainage blockages
- Keeping plants healthy with appropriate feeding and watering
- Monitoring structural solidity
Are all absolute essentials. Regardless of the type of green roof.
Green Roof Maintenance Considerations
The below should provide an example of the maintenance requirements, their frequency, cost and the types of roofs associated with each.
Drainage / irrigation
Bi-annual – monthly
£ – ££
Watering & feeding
Intensive / wildflower
Bi-monthly – weekly
Deadheading & weeding
Monthly – weekly
£ – £££
Intensive Green Roof Maintenance
Intensive green roofs are much larger roofs that typically have a greater variety of flora and fauna attached to them. Naturally this means the maintenance requirements increase.
Larger plants, with rangier root systems have greater nutrient requirements than small sedums or wildflowers. This means some intensive living roofs may need manual feeding and watering to encourage sustainable growth. Particularly in the months after initial planting where nutrients are so essential.
Extensive Green Roof Maintenance
Extensive green roofs are typically made up of lightweight, low maintenance plants like sedums, wildflowers and grasses.
As sedums and grasses in particular are largely perennials and have low nutritional requirements, feeding and watering is, almost, completely unnecessary. Particularly if the roof is laid from pre-grown kits or mats.
However wildflower roofs will require slightly more delicate watering and deadheading.
Sedum Roof Maintenance
As previously discussed, sedum roofs require very little maintenance. It can even be as simple as annual weeding to remove intrusive plants. Particularly if the roof is grown from a pre-grown green roof kit. Because they are such hardy, drought resistant flora, they don’t even need watering.
If the sedum roof has been grown from plants, or even seeds, then the maintenance required to make the roof thrive is significantly higher because there’s a bedding in period. One you don’t get with modular trays or kits.
Wildflower Roof Maintenance
Wildflower roofs – intrinsically more delicate than sedums – require more maintenance.
Monthly or quarterly deadheading and weeding is a very sensible option. As is continually monitoring water levels. You want the soil to be damp or moist. Not dry and crackly or over-watered. Wildflowers are more delicate plants and need to be treated as such.
Biodiverse Roof Maintenance
Biodiverse roofs – by their very nature – usually require almost no maintenance.
They are designed to encourage wildlife and as such, need to be left alone. Outside of the usual checks around drainage, irrigation and the potential removal of certain alien species. This is something to find out / discuss with your local council.
Green Roof Maintenance Costs
If you have an extensive, self-built green roof that is predominately made up of sedums and succulents, then – outside of the initial build – maintenance is almost entirely negligible. In totality we’d expect maintenance costs for a roof like this to cost under £100 per year.
However large, intensive green roof projects can cost tens, if not hundreds of thousands of pounds to create. When you increase the scale and cost of the initial project – involving higher value, less hardy plants – then the cost of maintenance can significantly increase.
Huge commercial projects can even have a full time gardener working on them.
Green Roof Maintenance Requirements Checklist
There are a few non-negotiables when it comes to green roof maintenance. The structural solidity of your roof is crucial. Obviously you don’t want it to rupture, so manually checking for cracks, leaks and issues with your waterproofing, filtration and drainage are monthly essentials.
Ensuring easy access, even for extensive green roofs. Pitched roofs (roofs on a slope) present their own difficulties. If your green roof sites on a V-shared roof, how will you manage it?
Yes green roofs are low maintenance. Particularly if the roof is extensive and primarily made-up of hardy, drought resistant plants like sedums.
If the roof is a larger, intensive project with multiple different species of flora and fauna, it will naturally need more upkeep.
Some green roofs need watering, some do not.
Hardy succulents and certain types of grasses are drought resistant and will cope throughout the entirety of each British season largely unsupported.
But certain wildflowers do need watering and more careful management.
Yes green roofs need weeding.
Weeds can takeover roofs and grow much faster than their sedum or wildflower counterparts. To mitigate this risk, regular-ish weeding is one of the few living roof maintenance essentials.
Sedum roofs do not need deadheading. However wildflower roofs – or any roofs that have blooming annual flowers – will need deadheading.