News and Articles
After all the rain we’ve had this spring and summer, green roofs should be looking wonderfully green and verdant at the moment. But what if they’re not? What could be the matter?
Extensive living green roofs, particularly ones created using a lightweight sedum blanket such as Enviromat typically include a shallow layer of specially engineered green roof substrate. Green roof substrates are not brilliant at retaining plant nutrients, simply because they don’t contain a lot of organic matter. That means that once the plants have finished their spring growth spurt, flowered and set seed they will have used up most of the nutrients in the growing medium and will be hungry for more. If the plants are to survive an indian summer and then a harsh winter, they need to be in tip top condition.
So how will you know whether or not your sedum roof needs feeding?
- Have you had plenty of flowers this summer? If flowers on your roof were in short supply, the chances are your roof has been hungry for a very long time and needs some TLC in a hurry. If you’ve had a really good floral display, plants will be heading towards exhaustion and will benefit from a light feed in the next couple of weeks.
- What colour is the foliage? At this time of year, and with all the rain we’ve had lately, sedum leaves ought to look like plump green jelly beans. If the foliage is bright red, all over the roof;or worse, if there aren’t many leaves at all, your roof could be in a muddle. Please send us a photograph and ask for advice before you do anything else.
- Are there any bare patches between plants? A healthy sedum roof will have a lovely thick sward of plants at this time of year with hardly any gaps between them. Again, please send us a picture if you feel plant coverage is particularly poor. It probably means that the roof is overdue for a feed but there may also be underlying problems such as issues with shade or drainage.
- Weeds: a few weeds at this time of year are to be expected, particularly after the rain we’ve had. Be sure to pull out any tree seedlings and if you’re worried about weed infestation, please email a photo to our Production Manager who will be able to advise you on how best to control them. Remember…..on an extensive green roof, weeds could indicate a problem with drainage or they could be a sign that nutrient levels are not quite right.
- When did you last feed your roof? Sedum roofs need feeding at least once a year. Twice a year if we have high rainfall or if the roof-pitch is greater than 10 degrees. If you’ve not applied any sedum feed since January or February this year, you’d be well advised to give it a feed this summer. If it’s been longer than that, it definitely needs attention…and the sooner the better!
What to feed
Enviromat recommends that you use Nutrifusion spring summer feed at a rate of 30g/m2 to give your green roof a boost. Apply it any time between the beginning of march and the end of September. One application per year is normally enough but if the weather has been particularly wet, the roof is steeply pitched or the plant layer is in poor condition, two applications may be needed.
Enviromat green roof services are publishing a guidance leaflet on designing green roofs so that essential maintenance to the plant layer is as simple, and therefore as cost-effective, as possible.
Green roof maintenance needn't be complicated or expensive but it is essential if the roof is to provide benefits such as insulation, cooling, aesthetics, biodiversity and wildlife habitat.
The leaflet offers guidance on aspects of green roof design such as slopes and drainage, access, health and safety requirements and plant choices and will be availalable free of charge from the Q Lawns team from 1st June 2012.
To request a copy, please email Angela on email@example.com
Enviromat are looking for a Green Roof Landscaper for our green roof maintenance division.
This exciting opportunity will require a qualified person with experience of horticulture and a head for heights.
The salary package will be commensurate with working for a large, progressive, diversified farming group.
Enviromat is part of Shrubhill Farms Limited
For more information, or to apply for the post, please contact
Shrubhill Farms Ltd
Most of the benefits of living green roofs can be attributed to the plants that are growing on them. Vegetation is clearly important for wildlife habitat and for aesthetics but they are also responsible for carbon sequestration, for the cooling effects of evapotranspiration, for filtering dust and pollutants from the air and for stablising the growing medium with their roots.
Experience has shown that without adequate maintenance, plant coverage is lost over time which leads to a loss of growing medium. Both are detrimental to the appearance of the roof.
Enviromat have begun working with Herriott Watt University to gather data to assess the importance of green roof maintenance and discover how performance is affected when the vegetative layer recieves no care or attention. This work is in the early stages and there are no definitive results as yet.
In the meantime, it's wise to check the condition of your green roof. Enviromat offer a free green roof inspection service. Simply e-mail recent photographs to firstname.lastname@example.org or telephone 01842 828266 to speak to one of our advisors.
Alternatively, visit stand S1702 at Ecobuild
It's a frequently overlooked fact that extensive green roofs need maintenance in order for them to deliver all of the benefits they were installed to supply.
A simple maintenance regime asks for two visits to the roof a year, one in the spring to check plant health and apply fertiliser if neccessary and one in autumn/winter to remove debris and unwanted plants and most importantly, to make sure that all of the drainage outlets are clear of rubbish and working properly.
Extensive green roofs frequently consist of mixed sedum species growing in a shallow layer of growing medium. Sedums are chosen because they are particulaly well adapted to living in poor soils in exposed conditions and they do very well on roofs BUT, there are two conditions that sedum plants cannot survive under. One is shade, the other is soggy ground.
It is therefore vital for the plants' survival that once autumn leaves have finished depositing themselves on top of the plants - so around November/December every year, facilities managers need to pick a fine, still day, don their woolly hats and their harnesses and get out onto the roof to check that all is well.
First job is to collect up all the dead leaves, carrier bags, rubbish and detritus that have found their way on to the roof in the last 6 months or so and remove them. Be especially vigilant in the corners, because that's where everything tends to congregate. Debris blocks sunlight from the plants, effectively keeping them in the shade and killing them.
Next, pull out any unwanted plants such as tree seedlings. They can form strong roots that are capable of damaging waterproofing.
Finally make sure that drainage outlets are clear and that rainwater can escape from the roof quickly and easily - water sitting on the roof for long periods of time not only increases the weight loading, it causes sedum roots to rot off resulting in the demise of the plants.
Where the facilities manager is pushed for time, or is not trained to work at heights, Enviromat offer a hassle-free green roof maintenance service. Our Green Roof Manager will carry out a free site assessment before advising on what work is needed and how much it will cost. Normally the cost is far lower than expected and the result is that any green roof will function far more efficiently throughout the year.
For more details, contact Mark Southwell on 01842 828266 or email email@example.com