Sedum and Green Roofs
One of the most popular plants for green roofs, especially for domestic premises, is sedum as it is light weight and easy to grow, with little maintenance required. Sedum is also much cheaper than other combinations of plants and is popular with those who want to build their green roof themselves.
What is Sedum?
Sedum covers a range of flowering plants that are from the family Crassulaceae and has up to 600 different variations across the world. Benefits for green roofs come from their water storing leaves, their attractiveness and their ability to withstand more harsh conditions.
Sedum facts you might like to know:
- Their leaves are generally edible though you may want to check that your plant isn’t one of the few that are toxic before you put it in your salad.
- They are found throughout the Northern Hemisphere and are often referred to as stonecrops.
- Some sedum’s have medicinal properties. Stonecroft acre has been used to treat epilepsy in the past.
- Sedum is largely preferred as a roof covering over grass because of its greater variety.
- Hardiness varies across species – some can handle the cold but not the heat and vice versa.
- The largest sedum covered roof in the UK is at the Rolls-Royce Plant in Goodwood that covers over 22,000 m².
- They provide a great habitat for insects including butterflies such as the Grey Chi.
- There are thought to be 55 species of sedum in Europe alone.
Types of Sedum
The variations within types of sedum make it an ideal plant for green roofs providing a breadth of colour and textures that are hard to beat. Purple Emperor produces dark purple leaves and lovely pink flowers in summer whilst sedum acre has elegant green leaves with yellow flowers.
Sedum Autumn Joy: One of the most popular perennials in UK gardens, this sedum has flowers that change over time, from the palest pink to rose and then a deep, rusty red.
Sedum Matrona: It has grey green foliage and pink flowers that stand out on mahogany coloured stems.
Sedum Neon: Neon’s the right description for this brilliant pink/mauve which turn to a deep rust in September.
Sedum Ogon: With its bright foliage and intricate yellow flowers this perennial is happy in the shade.
Sedum Sieboldii: Delicate and striking, this sedum has blue-green leaves and pink flowers that can brighten up any green roof.
Choosing the Right Sedum for your Green Roofs
The best time to design and install a sedum roof is in the autumn. It gives a chance for your green roof to settle and it will be more than ready to burst into life in the following spring. The benefit of sedums is that they can take a shallower soil level than many other plants and the most popular ones for green roofs are the hardiest, including:
- Sedum album
- Sedum ellacombianum
- Sedum ‘Dragon’s Blood’
- Sedum ‘Superbum’
- Sedum ‘Fuldaglut’
- Sedum kamschaticum
- Sedum ‘Fruland’
- Sedum ‘Green Form’
- Sedum ‘John Creech’
- Sedum ewersii
Sedum and Air Pollution
There has been quite a lot of research done recently on the effect of green roofs in reducing pollution, particularly in our city centres where flora is at a premium. It is largely accepted that green roofs, particularly those using sedum, can greatly decrease the surrounding pollution by filtering it out.
Sedum and Insulation
Both sound and heat insulation are great benefits provided by sedum green roofs. The noise produced in a house can be reduced by as much as 40 decibels before it reaches the outside. Green roofs also have a cooling effect in the summer and help keep the warmth in during the winter.
Sedum and Habitat Provision
Loss of vital habitats is one of the biggest problems our wildlife faces, in towns as wells as big cities. Providing the right vegetation can help promote the environment that will allow life to thrive and is greatly multiplied when there is a larger network of green roofs. Bio-diverse roofs are slightly different from everyday green installations with the addition of things like twigs and bark that birds can perch on and stones and sand which can become home to insects.
Reducing the Urban Island Effect
In dense conurbations there is such a thing as the Urban Heat Island Effect which means that these places suffer from higher temperatures – mainly because of the close proximity of people and the reflection of solar energy off roofs and walls. Installing a number of roof gardens in a city space can help reduce the heating up of the environment by as much as 4°.
Sedum and Water Retention
Heavy storms put a large amount of pressure on drainage systems in our cities and the addition of sedum roofs can help to manage excess rainwater and prevent flooding. Nowhere is this more evident than in a city like New York where excessive water from storms often caused flooding and damage in the streets, as well as contamination of municipal water systems, because the drainage system was unable to cope. The addition of green roofs that effectively soak up the storm water has saved an enormous amount of money over the last few years.