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What is Sedum and why Sempergreen® FAQs

Sedum is an evergreen, succulent plant, the natural properties of which make it extremely suitable for roof greening

Succulents are plants that store water in their leaves, and this is why Sedum is often referred to as a leaf succulent.

The metabolism of Sedum differs from other plants, in that, at night, carbon dioxide is absorbed through the stomata and converted into Malic acid. During the day, under the influence of sunlight, the Malic acid is decomposed and photosynthesis takes place. The stomata in the leaves are only open at night and during the hot and dry day, moisture loss is minimised.

Thanks to it’s natural properties, Sedum requires little maintenance when used for green roofs and generally only requires attention twice a year which includes removing weeds carried by the wind and applying fertiliser.

Unlike grass, there is no need to mow it, which makes it perfect for hard to access places such as roofs

Sempergreen Group was founded in 1996 with the mission of growing and supplying innovative Nature Based Solutions that make life in our urban areas, towns and Cities greener, cleaner, better for our Health and Wellbeing and increasingly important, Biodiverse…, and for generations to come.

Sempergreen is a Global Company with many nurseries and offices around the World and Sempergreen UK Ltd has recently been set up in response to the growing demand for great quality Green Roofs.

Sempergreen has a strong foundation of 27 years’ of experience developing and growing sedum blankets, which are grown in nurseries around the World. They work with Civil Engineers to test their sedum blankets extensively, which means they have been able to develop the best quality products on the market with the following benefits:

  • Sempergreen products are of the highest quality-tried and tested over many years and in continual development.
  • Upon delivery, your green roof will have a minimum sedum coverage of 95%, giving you an instant green roof.
  • We stock the Sempergreen green roof systems and products you see on our web shop, at our UK nurseries, which means delivery times are short
  • Our green roof products are produced completely free of pesticides and therefore make a positive contribution to the living environment of bees and butterflies

Web shops that carry the Sempergreen Certified Quality Mark, demonstrate that they are a certified seller of Sempergreen’s quality products for green roofs.

These retailers have been hand picked by Sempergreen, which means you can be confident that the web shop guarantees the best quality, reliability and service. 

Sempergreen’s green roof systems are tested by Independent Civil Engineers at Research & Development labs. There are many distinct benefits of choosing our lightweight systems including:

  • Sustainability: made from sustainably sourced various rock mixtures.
  • Great for plant roots: the lightweight open structure promotes extensive root distribution and plant growth.
  • 8 x lighter than a traditional soil based green roof, meaning it can be installed on most building structures.
  • High water absorption: up to 10 x better absorption and retention than a traditional green roof which means a better performance of storing rainwater run-off.
  • Efficient and quick installation: 20 x less material needed than a traditional green roof meaning significantly less labour and time saved.
  • High fire resistance: grown on a non-combustible medium that will not contribute to the spread of fire at any stage.
  • High acoustic performance: reduces noise levels through surface absorption. 

The addition of a sedum green roof will protect your roof from extreme weather conditions such as heavy rain, ice and intense sunshine, and the addition of a green roof can increase the lifespan of your roof by up to 23 years.

A green roof also cools the roof below which in turn, reduces fluctuations in temperature and exposure to UV light, which can damage the waterproof layer over time.

Extensive Green Roofs are thin lightweight roof systems that typically have a planting media measuring 4 to 20 cm deep, with a saturated weight from 45kg/m2 to 150kg/m2 meaning this type of roof can be installed on a wide selection of roofs.

Intensive Green Roofs are much heavier and thicker as their growing media ranges from 20 cm to 100 cm weighing from 180kg/m2 and up to to 500 kg/m2 saturated;

Semi intensive green roofs, as their name states, are a combination of the other two types. They have a thinner planting media than an intensive roof but thicker than an extensive one, and the whole system ranges from 120 to 250 mm with a saturated weight from 120-200 kg/m2

An Extensive Green Roof offers a number of advantages over an intensive green roof:

  • Lower costs
    The installation and maintenance costs of an Extensive green roof are relatively low compared to Intensive green roofs.
  • Less load on the support structure
    An Intensive Green Roof is many times heavier than an Extensive Green Roof, as it’s comparable to a garden with shrubs and trees, but on your roof. The load for the roof construction is therefore much higher. Intensive roofs can therefore only be constructed on new buildings where the weight of the roof is known.
    Conversely, Extensive roofs can easily be installed on almost any kind of roof; flat or pitched. 
  • Minimal maintenance
    An Extensive green roof requires minimal maintenance. It is enough to fertilise twice a year whereas, an Intensive green roof requires regular maintenance such as pruning and strimming/mowing to keep the plants in good condition, just as you would in an ordinary garden.

Delivery FAQs

Delivery is dependent on the volume of green roof system you purchase. and which system and products.  The website will automatically calculate the delivery charge for you, and we work with the UK pallet network and each pallet costs £84 + VAT. Each system has a different volume per pallet.  Please get in touch for delivery costs of any items from the Products page or if you require something that isn’t standard on our website and we will provide a bespoke delivery cost.

The minimum amount of green roof system we can supply is 10m2. and the amount you put in your basket will automatically default to 10m2.  This is because there is a significant amount of work involved in rolling our sedum blankets off the field and then packaging it together on a pallet.   

Also, as our products are delivered on pallets, the full pallet price has to be charged even for small amounts of green roof system.

We have a lead time of 6 – 12 working days. Our order cut off time is Tuesday at 6pm for delivery the following week. We deliver on Thursdays and Fridays. Specific times of day for delivery may be possible if your local depot offers this, please note there is an extra cost for this so please get in touch

Please check out our Delivery and Terms and Conditions pages for more information.

The delivery driver will deliver the goods on the pallet to the kerbside only. It is then your responsibility to unload the pallets and ensure that there is appropriate access for delivery. It is your responsibility to dispose of the pallet your order is delivered on.

Please check out our Delivery and Terms and Conditions pages for more information.


We deliver to all areas of the UK mainland including London.

With people spending more and more time at home, the environment is more top of mind, and even the smallest piece of ‘green’ can provide a calming effect on our minds and bodies.  It is becoming increasingly popular to install a green roof in built up, urban city locations, like London, many enquiries are for smaller flat and slightly pitched roofs for example of extensions,  shed roofs and bike stores 

When you put your address into the website, it will automatically tell you if we deliver to your area and will calculate the delivery price.  In some instances you will need to get in touch with us to discuss your requirements.  Simply complete the contact form or call us on 0161 445 0001 or email

Installation FAQs

Yes you can depending on the size of your project. We offer specially tailored DIY packs with instructions and videos for your installation. See our installation page for more information and videos.

We may be able to introduce you to an experienced installer from our preferred network, just give us a call and we can advise you.

Yes you can.

The most important piece of information required is if the existing roof is strong enough to carry a green roof system. It is your responsibility to determine this via the Manufacturer, Builder, Architect or Structural Engineer. We do not advise on this.

It is crucial that the waterproofing layer/membrane on your existing roof is fully waterproof before installing a green roof system.

Yes. The surface must have a waterproof covering before your living roof is added. Most roofs will have one of the following:

  • Single Ply 
  • GRP Fibreglass
  • EPDM Rubber
  • Felt
  • Concrete

Unfortunately, we cannot advise on this and it is your responsibility to determine the Weight Bearing Capacity of your roof via a Structural Engineer, Architect, Building Contractor or Manufacturer of the building e.g. a garden room

Yes it can, 12 months a year! The only limitations are frosty conditions, snow and extreme heat. If in doubt please get in touch.

Roof style and system weight FAQs

Yes, although a slight pitch is preferable. You can have a green roof if your roof is flat and up to 15º. If your roof pitch is over 15º please contact us for advice and guidance on the best solution. 

You will need an “edge” to hold the system in place and this can be an up-stand or parapet.  If you don’t have a parapet edge we can supply roof edge trims as shown on our Products page. Please get in touch if you need advice about this.

The drainage layer is there to allow excess water to run off.  This also means that the substrate layer won’t become waterlogged.

There are 2 types of substrate layer for our green roofs:

  • Roof garden substrate is the growing medium in which the green roof plants grow. A special mixture is available for each type of green roof; extensive or intensive. This specially designed roof garden substrate ensures that each layer of vegetation gets the proper nutrition, despite the limited thickness of the soil layer.

    This substrate is usually for heavier weight systems and where the weight bearing capacity of the roof is known. If you are in the planning stage of your extension or new build, you can employ a Structural Engineer via your Architect to work out the maximum weight your roof can hold. This will then dictate which system you are able to choose.

  • Substrate roll is a lightweight, green roof substrate. It is manufactured from long mineral wool fibres and forms a compact and stable layer. The composition has been designed so that it has excellent water absorption properties.


Substrate roll can serve as a lightweight substitute for roof garden substrate. It is a good growing medium and as such, is ideal for a lightweight substrate layer for an extensive green roof.

Substrate roll is available in 2 thicknesses, 20mm and 40mm. We will be happy to advise you of the best solution for your green roof. are a few reasons:

  • Aesthetic: some roof designs use stone areas to create artistic patterns or even a simple border to add character and a “picture frame” look.
  • To act as a Fire break: the FLL Guidelines and the GRO Green Roof Code include requirements for the provision of fire breaks within green roof design
  • Wind resistance: particularly in blustery areas, a stone border can be used to prevent the chance of wind uplift pressures on the green roof
  • To prevent debris: a stone border can effectively stop wind-borne plant parts and debris reaching the edge of the roof and gutters

Maintenance FAQs

The amount of maintenance required really depends on the type of green roof you have installed.

Sedum roofs require little on-going maintenance, generally twice a year, Spring and Autumn, is enough and a general clearing of gutters, a little weeding along with fertiliser should suffice. See our maintenance page for more information.

Biodiverse & Wildflower roofs do not require any additional watering or feeding as  this could alter the natural balance of plants on your roof. Also, the addition of extra nutrients and water will only encourage excessive growth in the grasses, which will consequently out-compete the more desirable native plants. Only under very dry conditions, is it necessary to irrigate at least 1 hour once a week.

Mowing and strimming will be required with these roof types. See our maintenance page for more information.

Sedum plants are used in green roofs because they hold a lot of water and are incredibly hardy. Under normal circumstances the roof should not need regular watering. However, live material must be irrigated immediately following installation. This irrigation must continue in the first few months following installation and again in especially hot and dry periods. Full saturation of the system is recommended once a week in these periods.

Sedum Conditioner and Sedum Nutrition are both slow-release fertilisers but Sedum Nutrition is an organic option.
Each should be used directly after installation and then each April/May and September/October for the ongoing health and maintenance of your sedum green roof.

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