Plants for green roofs: sedum and other hardy species
Extensive green roofs have a thin layer of substrate (usually 6–15 cm), are not watered or watered very rarely, and are exposed to sun, wind, heat and frost. Only a few groups of plants survive these conditions, and sedum species are the basis of almost every extensive green roof.
Why sedum?
- It stores water in its fleshy leaves and survives weeks without rain.
- It has shallow roots, suited to thin substrates.
- It tolerates strong sun, wind and frost.
- It forms a dense carpet that protects the substrate from erosion.
- It needs no mowing and very little maintenance.
Recommended species
Sedum 'Angelina' has golden leaves that turn orange in winter and is one of the most used species for green roofs. Sedum hybridum forms a dense green carpet with yellow flowers and is extremely frost-hardy. Sedum rupestre 'Blue' adds blue-grey tones, and Sedum 'Watson' pink-green rosettes. Combined in bands or patches of different colours, these species create decorative patterns visible from above.
On slightly deeper substrates you can add Festuca glauca for texture and Iberis sempervirens for white spring flowers.
Planting density
| Plant | Plants / m² | Notes |
|---|
| Sedum (various species) | 9–16 | Denser for quick coverage |
| Festuca glauca | 7–9 | On substrate of at least 10–12 cm |
| Iberis sempervirens | 7–9 | In areas with deeper substrate |
Planting and maintenance
- Planting is done in spring or early autumn, on special green-roof substrate.
- In the first 4–6 weeks the plants are watered regularly until they root.
- Once established, watering is only needed in very long droughts.
- Once or twice a year weeds are removed and gaps are filled.
- Fertilise rarely and moderately – too much fertiliser weakens the plants.
Not just on roofs
The same plants are very good for planters on terraces, retaining walls, rock gardens, roundabouts and other sunny areas without irrigation. See also the guide Drought-tolerant plants for public green spaces.
PlantDGD supplies wholesale perennials, including sedum for large areas. For a quote, send us the area in square metres and the species you want via the contact page.
Frequently asked questions
How many sedum plants are needed per square metre of green roof?
Usually 9–16 plants per m², depending on plant size and how quickly you want full coverage.
Does a sedum green roof need watering?
Only in the first weeks after planting and during very long droughts; once established, sedum survives without regular watering.
Plants from this guide, available wholesale