Thursday, 17 April 2014

If green roofs are “low maintenance” why do they need feeding?

When sedum green roofs first became fashionable in the UK, one of their USP's (unique selling points) was that they are "low maintenance".  Unfortunately, architects, developers, buildings' managers and maintenance folk interpreted "low maintenance" as "no maintenance"

Oh dear.

That was very wrong indeed.

  • A sedum green roof IS drought tolerant --- so it rarely needs irrigation.  
  • It is frost hardy----so doesn't need replacing after a bad winter.  
  • It is low growing----so it doesn't need mowing, pruning, clipping or any of the other gardening jobs associated with herbacious perennials.
  • It is quite thrifty when it comes to nutrients----so no need for frequent feeding as you would roses or tomatoes.
However, what is often overlooked with such an easy-going plant palette is that
  • A sedum roof IS a living thing.  Which means that it DOES need an adequate supply of water and of the right nutrients.

Plants like this Sedum spurium need a booster feed in spring when they're growing on a roof

A living green roof is just like a huge container garden.  The plants growing in it have a finite amount of growing medium to get their roots into.  That means that there is a limited supply of nutrients for them to enjoy.

A green roof is equivalent to a large, shallow plant pot.
It needs similar care to your houseplants, raised beds and planted containers----but on an industrial (and more manageable) scale

At ground level, microscopic organisms in the soil pull nitrogen from the air and recycle dead plants and bugs to make a certain amount of plant food.  BUT, on a green roof, the substrate (growing medium) has been engineered to suit the needs of the building (light weight, free draining, with particles that are too big to wash off).  Green roof substrate is super, but the structure of it doesn't support soil microbes very well.

In addition, the harsh conditions on a roof put extra strain on the plants’ metabolism so, just like us when we’re working hard, green roof plants need the right food (and plenty of it!) to keep them in good health.

So, even self-sufficient plants like sedums need a little extra help if they are to thrive on a green roof and provide all the benefits you want them to.   ie insulation, cooling, wildlife habitat, good looks, showing off your "eco" credentials.

Here's what you need to keep your green roof in tip-top condition:

If you're still at the design stage.....choose your plants carefully and put plenty of thought into how your green roof will be maintained in the years to come.

If you already have a living green roof you will need some of this

Enviromat Natural Green Roof Feed has been specially developed to help you and your clients to get the best out of their green roofs.
It comes in a bucket – so it’s easy to carry up on to a roof.  The granular feed is easy to store and easy to apply.
YUK! a neglected sedum roof.  The hungry plants are too weak to hold the growing medium in place with their roots.  This roof looks ugly and its thermal performance is probably very poor.  It's not much use to wildlife either.

The formulation for this highly specialised feed is 7.9% Nitrogen, 2.97% Phosphorus, 2.47% Potassium and a whole host of essential trace elements that are needed to keep plants healthy in stressful conditions.  Enviromat Natural Green Roof Feed is a slow release feed, so on a healthy living roof, one feed a year is enough. 

Order your Green Roof Feed online or phone Q Lawns for a quote: 01842 828266

Friday, 26 October 2012

Electricity prices are rising so install a green roof

Today I arrived home from work to a seasonably chilly house and a husband who's mood could only be described as icy....our electricity supplier has announced an 11% price hike and he's not happy.

So what does that have to do with green roofs?

Newly installed green roof just begging to
have PV panels added
Well, to start with, a green roof is a fantastic insulator, keeping a building warmer in winter and cooler in summer so savings there on the heating bills.  I speak here for the lucky souls who happen to have "greenable" roofs on their homes.  Our house was build long before electricity, let alone green roofs.  It has a steeply pitched, tiled roof and although it's strong enough to support a green roof buildup, the installation and maintenance would be a nightmare.  So, until we retire into something more suitable, there'll be no living roof on our house to help save electricity; 

So what about generating our own power with solar panels?  My friend Ginny and her husband Chris swear by them.  Chris installed PV panels on their roof in Essex and when they moved to the depths of deepest Norfolk, the solar panels came too.  Apparently the solar panels provide all the hot water they need in the summer months so the only fuel they use between late spring and mid-autumn is for cooking, boiling the kettle for tea and maybe watching a bit of telly.

Again, hubby says PV panels won't suit the look of our pretty house, BUT, being a farm, we do have outbuildings and so maybe he'll be persuaded to put use at least one of them to generate our own power and show the electricity company what he thinks of their pricing structure.

If however, he installs PV panels in conjunction with a living green roof, we'll be quids in.   Solar panels work best when the temperature is below 30 degrees celcius. Of course on a roof, in summer, temperatures can rise a lot higher than 30 degrees, thus rendering the PV panel less efficient; but if it's a green roof, the cooling effect of the plants will keep the temperature more comfortable and the PV panels will be more efficient.  PS...remember to design the roof so that panels are not casting shade over the sedum plants..they don't enjoy being kept in the dark

Research in Germany compared  PV cells over a green roof  with cells over Bitumen roofs. In over 5 years of recording, the panels over the green roof showed an average 6% increase in yields

I like it! So here I am, in my kitchen, log-fired Rayburn creating a nice warm fug around me.  Laundry is drying on the clothes horse in front of the fire, kettle is whistling and I'm wondering how I can persuade my dearly beloved to leave the comfort of the armchair to climb on the roof, install some Enviromat and wire in some PV panels before electricity prices go up in December.  I'll let you know how I get on.

Oh....if you fancy a green roof yourself, drop me a line and I'll send you a copy of our "how to" guide and a phone number for our installation man in case you'd rather sit by the Rayburn and let someone else do the work (like me)

Tuesday, 18 September 2012

Butterflies and bees on sedum mat

The Sedum spurium in Enviromat sedum matting always looks fantastic at this time of year and it's a great source of nectar for butterflies and bees. 

Here are some pictures I took outside our office this morning (18th September)

butterfly on S. spurium

bumble bee feeding on Sedum flower
sedum spurium - a popular flower with late summer butterflies
butterflies add extra colour to Enviromat sedum matting
bumble bees don't mind a slight drop in temperature so long as they have flowers to feed on

Monday, 6 August 2012

Meadows on Green Roofs

Peppa Pig World has a fabulous wild flower meadow growing on it's roof.  But how should wild flowers best be established on a smaller green roof and is Q Lawns' product Meadowmat the best way to go about it? 

This isn't Meadowmat on a roof but you can see that
a very grassy green roof could be difficult to manage
At first glance, you might think Meadowmat is a good green roofing material.  It has a great mix of native species, growing on to a matting system so it's easy to handle and gives instant coverage.  But, Q Lawns  also grow Enviromat sedum matting on our farm and we have a green roof maintenance service so we’ve had a little bit of experience with living roofs and in all honesty, Meadowmat isn’t ideal for several reasons

·         Meadowmat contains 34 species of native plants, all of which are found naturally in meadows, pastures etc.  Some of these plants are adapted to living in really poor soils so they’ve evolved vigorous root systems that can spread a long way to find the nutrients the plants need.  Vigorous root systems + green roofs could cause difficulties
·         The minimum depth of growing medium to establish Meadowmat into is 150mm.  That will weigh around 250Kg per square metre….an awful heavy load to put on a roof unless the building has been designed and built especially to carry that weight
·         50% by weight of the Meadowmat seed mix is grass.  A certain amount of native grasses are needed to supply food for insect larvae and shelter for amphibians and small furry creatures.  On a roof though, too much grass is a nuisance.  Meadows need careful maintenance to ensure that the grasses don’t predominate and crowd out less competitive flowering species.  That means taking a cut of hay in the summer….all of which needs to be brought down from the roof, and then mowing it a couple of times during the autumn and winter and again, removing all of the cuttings.  Unless you have really good access to the roof, the maintenance regime for Meadowmat just isn’t practical
·         Some of the plant species in Meadowmat can grow quite tall (I have Meadowmat in my garden which is currently at hip height) and in windy, blustery conditions, they blow over and all lay on the ground in a heap with the plants on the bottom of the heap being smothered out and killed.  On the roof, conditions tend to be more extreme than at ground level…hotter and drier in summer, colder in winter and windier all year round.  It’s best to stick to low growing plants that can cope better with the conditions

An Enviromat green roof is relatively lightweight and
has a long flowering period
Enviromat is the ideal vegetation blanket for creating a green roof……’s a relatively lightweight build-up and the plants, when in the wild, tend to be found on mountain tops, moors and heaths where they are adapted to living in exposed conditions.

If you are dead-set on growing wildflowers on your roof, be careful to select ones that are not too tall, can survive in exposed conditions, won’t need a huge amount of maintenance and give a nice long flowering period to provide nectar for butterflies and bees.  Also, avoid grass in the seedmix if you can….you’ll find that by sowing wildflower seed or planting wildflower plugs, grass will naturally establish itself in the spaces between flowering plants.

Wednesday, 27 June 2012

Green roof is a real eyecatcher

This shepherd's hut with a sedum roof attracted a lot of attention at the BALI Landscape Show at Stoneleigh on June 19th and 20th.   The roof was created using Enviromat sedum matting and took less than an hour to install.

First of all, Mark Pawsey, our Green Roof Manager, spread a layer of polyethene over the roof to protect the waterproofing from potential damage from roots and boots.

Next he added a layer of water retention matting...Mark's top tip:  always measure the roof and cut materials to size on the ground...that way you won't accidentally cut through the waterproofing.

Finally, the Eviromat sedum matting was lifted on to the roof and manouvred into position.  It took two people to lift each piece of Enviromat on to the roof, but Mark did all the fitting by himself, before watering the sedum plants thoroughly.

Minutes later, the roof recieved several visitors in the form of hungry bumble bees who found a feast of pollen and nectar from the sedum flowers.

Thursday, 31 May 2012


Welcome to the new blog from Enviromat green roof services.

Enviromat work closely with the UK’s leading green roof installation company; growing their sedum matting and helping to research and develop new ways of establishing plants on to green roofs of all shapes and sizes.
We also make Enviromat sedum matting available to builders and gardeners who want to create small scale green roofs on garden buildings, extensions and the like. We're also developing a native species mix for folks who want something a bit different.
This blog aims to provide as much information as possible on creating a living green roof, from loadings to plant choices, installation tips to aftercare advice.
Please use the comments box to ask as many questions as possible can and we will answer them as quickly as we can.
Our first post is about plant here to find out what to consider when you're choosing the plants for your green roof.