Monday, January 31, 2011

Green Roof Thermodynamics Video - Night Temperature Reading Comparisons

Short video of one hour after sunset temperature readings of an non-irrigated, extensive green roof as compared to adjacent asphalt shingles.

Extensive, non-irrigated green roofs have a tendency to act as heat sinks and store heat during the day, releasing the heat during the evening back to the air and to the roofing structure underneath.

Green Roofs Design Guidelines - A Model - for Dry & Arid Climates article, Part One of a Four Part Series on Design Guidelines for designing green roofs in dry, hot and arid climates.

The information presented is tailored to nature irrigated green roofs and native plant species, however the design principles can be used to create all types of successful green and vegetated roofs, including rooftop permaculture and food gardens.

We cover all the most significant green roof design variables and inputs.  Part Two to be published shortly!  Be sure to read Part One - The Introduction.

You can click on the above link or use the following URL: 

Happy Green Roofing!


Sunday, January 30, 2011

Sparrow & Dew Catchers Sparrow on the Green Roof on the Green Roof

Walked outside and the sparrows were all over the green roof.  Spring is coming! Ran back in, grabbed the camera and shot a photo before they all flew to the garden..

BTW - the dew catchers work great - just need to be removed in the event of a cyclone :)

Green roofs are so very critical to reestablishing foraging and communal habitat in the Urban Core and supporting biodiversity.

Sparrow on the Green Roof

Extreme Lightweight, Nature Irrigated, Native Species Green Roofs with Polypodium polypodioides

Humankind many times has had the tendency to over-engineer, over-design and improve upon what Nature has long before already perfected.

Eons before we humans came up with idea of putting plants on roofs to attract wildlife and cool and insulate our abodes and structures, Nature was already putting plants on roofs for the same and many more purposes.

Not to be stymied by the lack of structural support many of our roofs offer, Nature creates some of the lightest weight, nature irrigated native species green roofs ever - and Polypodium polypodioides is one example.

One of the most oft-heard concerns is green roof weight.  Many intensive green roofs can weigh over fifty pounds per square foot (ten Kg/Sq.M) when saturated with rainwater.  Extensive roofs, too can be quite heavy.  Some extensive green roofs, though much thinner with respect to soils depth range from fifteen to thirty pounds (three to six Kg per square meter).

Polypodium polypodioides

Polypodium polypodioides

A natural Polypodium polypodioides covered roof system can weigh less than three to four pounds per square foot (less than one Kg per sq. meter)!

Polypodium polypodioides possess photosynthetic metabolisms and so CO2 is sequestered and O2 is produced.

Polypodium polypodioides provides much needed native forage and communal habitat for many native wildlife species.

Polypodium polypodioides is beautiful, aesthetic and visually attractive (beautiful photo of resurrection fern here).

Polypodium polypodioides

Polypodium polypodioides loves to absorb stormwater, removing contaminants and helping keep waterways, rivers and lakes clean.

The adaptive and interesting root architecture of Polypodium spp. is discussed in a recent blog post here.

In fact, Resurrection fern,  Polypodium polypodioides, was the first fern in space - going up on a 1997 Space Shuttle Mission to see if the roots would absorb water in a space capsule!

Polydodium Green Roof

As with any green roof plant, Polypodium has certain considerations to be taken into account during green roof design.  As with most plants, during long periods of drought the plant appears brown and dry.  Proper integration with other species, such as evergreen CAM plants is an easy solution.

Any dry organic matter may also present a fire issue.  Tall, prairie-type grasses used on green roofs produce much more dry-leaf matter than Polypodium.  Again, proper integration with other species, such as evergreen CAM plants is an easy solution.

Perspective of native plants is one where we can either;
  • look at a native plant, consider it a weed and find problems with it, or
  • look at a native plant, consider biodiversity and wildlife value and listen to Nature.
One of my favorite follows on Twitter is @jardsustentable - a wonderful perspective about listening to plants and working with Nature rather than trying to mechanically change Nature.  Check out JardSustentable's tweets here! 

Following JardSustentable's Twitter advice about working with Nature is an excellent approach to take when designing a natural irrigated and native species green roof.

Look up into trees.  Look up at the roofs of buildings.  Look up into rain gutters.  Watch what plants grow in rock out-croppings.  Examine highway bridges, building walls and bulkheads.  Look to Nature to see what she recommends for local plants for growing vertically.

Look Up for Potential Green Roof Native Species (Polypodium in Juniperus spp.)

So consider integrating resurrection fern into the next appropriate green roof project.  With an over weight of less than one Kg per meter square, the plant can provide a lush tropically green look with no additional irrigation - though a recycled-rainwater micro-irrigation system would work wonderfully also!

As always, comments and emails are appreciated and happy Green Roofing!


Saturday, January 29, 2011

Fog, Dew & Green Roofs for Biodiversity & Habitat

Plants Capturing the Dew - Nature based Irrigation for Green Roofs
We are headed to St. Augustine today to take photos of a couple older well established nature type green roofs.

Will post photos later today.

Walking by a portion of my green roofs this morning I noticed thousands of dew drops, like crowns on leaves and had to snap a photo. This is what taking advantage of nature based irrigation is all about. Using and arranging plants to capture what nature offers.

And while I was up on the roof shooting the photo I noticed a feather. on a parsley plant. Two doves, a mating pair, have been recently using portions of the vegetated roof for nesting and foraging.

Biodiversity, food and water conservation.

Habitat and Dew.

Green Roofs at their finest!

Biodiversity and Food Green Roof Project for Habitat, Education and Research

Breaking Ground Contracting is a leader not only in sustainable construction but also in sustainability education (the BGC educational blog is a great educational resource).

As they remodel their corporate office, the project is on track for LEED Platinum certification.

The building roof will house an extensive array of solar PV panels and an extensive green roof with native plants for biodiversity and permaculture food plots for educational purposes.

In fact, the entire building will be an educational example of just how true sustainable construction practices can be accomplished on a cost-effective basis.  Wooden wall and ceiling timbers and boards were carefully removed, nails pulled and reused, the concrete block walls preserved, insulation added and much more.  Computer systems will monitor and measure the sustainability characteristics of the office and these data will will be made available to students to learn about green building practices.

We are working with Breaking Ground Contracting on their exciting green roof design and installation.

The roof will be accessed by a exterior spiral staircase as shown here.

Breaking Ground Contracting - Green Roof and PV Access Stairway
The solar PV panel frames are pictured below.

BGC Solar PV Panel Array Frames

The MV extensive vegetated roof will be constructed using a combination of Colbond mats over 60 mil Firestone TPO.  The roof TPO layer will be protected by an additional sacrificial 60 mil TPO layer.

Firestone TPO layer will support Biodiversity and Permaculture Green Roof

In preparation for the installation that will occur in February 2011,  food permaculture and native plant pre-vegetated mats were begun.  The photo below is of a woven and calendered mat.  The mat is filled with a green roof soil media specifically designed for the BGC site and locale.

Green Roof Planting Mats Prepared for Native and Food Species

The Breaking Ground Contracting building will also include innovative living walls and a rain garden/bio-swale system to reuse site runoff and rainwater,

We will be posting photos as the project proceeds.

As always, your questions and comments are appreciated!


Friday, January 28, 2011

Wheat Grass Green Roof Modules and Feeding the Cities From Rooftop Gardens

Rooftop permaculture holds the key to feeding the cities.

Here are a couple lightweight rooftop vegetable growing panels.

Easy to grasp and pick up, 52mm thick and they clip together allowing for many designs and layout configurations.

The wheat grass will be thick in a couple days.

MV Wheat Grass Green Roof Modules

MV Wheat Grass Green Roof Modules

The next photo is of the MV rooftop veggie growing area.

Rooftop permaculture - Veggies grow better on the green roof!

Not surprisingly, the rooftop veggies look better than those growing on the ground in the garden.

Garden soils here in Florida are widely inflicted with nematodes.

Nematodes burrow their way into a plant root, causing the root to swell into nodules and damaging the plant's vascular system - resulting in stunted plant growth and limiting produce production.

However the rooftop garden tends to stay nematode free.  Solarized by the sun's rays, rooftop garden soil tends to stay free of many of the common plant issues found in ground level soil.

We are working on a rather large rooftop permaculture and biodiversity project on a LEED Platinum building.  Photos and data to follow!  In the meantime, check out the Breaking Ground Contracting's Education Blog by Catherine Burkee here -

Industrial Agriculture is one of the most intense forms of land use.  Machinery chops the soil and vegetation covering the ground, pulling up and discarding all native plant DNA.  The soil is graded and tilled, plowed and fertilized.  All traces of the original soil structure disappears.   Pesticides, herbicides and fertilizers are soaked into the ground.

But  it doesn't have to be this way.

We can reforest the farmlands, restore wetlands, recreate habitat and replant what we've destroyed.

We can use the millions of urban rooftop acres for green roof gardens.  Rooftop permaculture.  Feed the hungry.  Feed the cities. Provide habitat. Reduce heat island effect. Clean stormwater. Sequester Carbon and pump fresh oxygen into a stale atmosphere.

But we need to be smart about how we accomplish this.

Today on Twitter I read the pundits as they laughed about how Toronto was backing down from green roof legislation.  The industrial lobby may have successfully convinced the city that green roofs are not cost-effective alternatives when compared to white TPO or single-ply reflective roofing materials.

So there will be two types of green roof initiatives in the future.  One will grow stale and eventually disappear, relying on expensive, heavy planting systems and monocultures of non-native highly temperamental landscape plants.  

The other will become dynamically organic in growth, seek out eco-friendly components and methods using ultra-light weight (less than 10 pounds per square foot) systems with nature-based or highly efficient recycled rainwater & micro-irrigation systems.  Native plants for biodiversity contributions and ethnobotanicals such as food, fiber and medicine plants will flourish.

Expanded shale with it's huge carbon footprint will no longer be used for planting media.  On site composting of organic material for the green roof will become the norm.  Drainage technology advances will allow for this accommodation.  Moreover, composting and reuse of organic matter conserves a rather large water footprint.

Mega-heavy, expensive green roofs will give way to the small commercial building and residential rooftop garden.  Governmental efforts in the green roof arena will be overtaken by grassroots local initiatives and small rooftop gardens will appear throughout the neighborhoods, especially as food prices rise and the dangers of pesticides, herbicides and chemical fertilizers become known.

The potential is exciting.

We can feed the cities.

We can reforest our agriculture lands.

We can envision the urban core ripe with organically grown, open-pollinated rooftop gardens, supporting bees, insects, birds and wildlife.

Millions of acres of green roofs.

It begins with a rooftop wheat grass tray and small veggie garden.

Rooftop Permaculture, Organic Dinner Salad from the Green Roof!

No room to have a garden?  Do one on your roof.

Rooftop gardening is easy and fun.  Pollinators are attracted to the plants and flowers and the rooftop garden provides wonderful habitat to a variety of bird, insects and wildlife.

These are the salad greens for tonight's fiesta, fresh from the rooftop!

We CAN feed the cities.  All we need is open-pollinated seeds (non-GMO), sunsterilized organic compost and sand or soil, a frame and a little desire to eat better foods.

Organic Rooftop Dinner!

Happy Green Rooftop Permaculture!

Providing Habitat and Biodiversity, Green Roofs - Restoring Volumetric Green to the Urban Core!

I am always amazed at just How much habitat Green Roofs provide within the Urban Core.

Is a sea of concrete and asphalt, wildlife are driven to Urban Green Roofs in masses.

Walking outside this cool, sunny morning the insects were buzzing around the green roof plants.  Some of the vegetables on the food roof were forming flowers and word had quickly spread to the pollinators.

Not to be proven wrong by the oft-quoted UK's John Ray (A collection of English proverbs 1670, 1678)
"The early bird catcheth the worm."
the birds were hanging out in the trees waiting for breakfast.


Watching Sun's Rise Across the Greenroof, Cardinalis cardinalis

Pileated Woodpecker (Dryocopus pileatus)

Watching the Green Roof from Above, Red-tailed Hawk (Buteo jamaicensis)

While other areas of the Urban Core whither away without plants, we find ourselves in a mini-oasis of wildlife.

The photos here were taken with my son's Canon EOS Rebel about two hours ago.

Green Roofs - promoting biodiversity in the Urban Core!

Happy Green Roofing!


Thursday, January 27, 2011

Green Roof by Nature, Cladina evansii & Wood Shingles

Cladina evansii is commonly referred to in Florida as Deer Moss or Deer Lichen.

Deer moss is an indicator species of clean air.

I found this wood shingle roof today covered in Deer Moss.

Nature Irrigated, Native Species Green Roof Superb.

Cladina evansii Deer Moss Vegetated Roof

Wednesday, January 26, 2011

Living Wall 'Crois Cheilteach'

20mm thick Living Wall
  • Copper cross
  • C3 plants
  • nature irrigated
  • carbon sequestering
  • oxygen producing
  • habitat creating
Living Crois Cheilteach

(Give it a couple of weeks and it will really be green....)

To hang on the Kitchen Wall.

by Kevin Shea

by Kevin Shea

Update on The Rabbit Hutch Green Roof!

The C3 Plants are firing on all cylinders! Photosynthesis is in high gear! Looking Greener after Day Four...

Extensive Green Roof for Rabbits.. :)

Sunday, January 23, 2011

Green Roofs, Biodiversity & Endangered Species

There are many, many reasons to construct a green roof, including;
  • Cleaning Stormwater
  • Reducing Heat Island Effect
  • Creating Sense of Place
  • Providing Habitat for Urban Core Wildlife
  • Preserving Biodiversity
  • Sequestering Carbon
  • Producing Oxygen, and more.
There are many other, less expensive roofing technologies capable of;
  • Cleaning Stormwater, and
  • Reducing Heat Island Effect
However, besides Green Roofs, there are no other roofing technologies with the benefits of;
  • Providing Habitat for Urban Core Wildlife
  • Preserving Biodiversity
  • Sequestering Carbon, and
  • Producing Oxygen
 In the long term Green Roofs may well be recognized as most responsible for preserving the heritage of our endemic biodiversity.

Because of the potential for Green Roofs to provide refuge to native plants, particularly those threatened and endangered by real estate development pressures, and endemic wildlife especially dependent on those native plants we must consider carefully those plants we specify into a green roof design.

With open space disappearing within the Urban Core, vegetated rooftops provide an opportunity to ensure native and endemic plants continue to thrive within the city.

Passiflora incarnata, Drought tolerant native plant for Florida Green Roofs
Soil media and mixtures can be formulated to mimic many of the site existing soil characteristics, such as mineral content and pH.

Gaillardia, Blanket Flower is a Florida Drought Tolerant Native Plant Perfect for Green Roofs
Research has shown local wildlife need certain types of common plants for foraging, larval food while other wildlife are specialized and actually required by the endemic plants for successful pollination.

The Monarch butterfly's, Danaus plexippus larvae feed on Asclepias spp., Milkweed plants.  Adult Monarchs will reportedly only breed where Asclepias grows.  Once proliferate across Florida, Asclepias has rapidly diminished in populations numbers due to loss of habitat in the Urban Core.

Monarch Larvae Feeding on Asclepias

 Asclepias or Milkweed is a hardy native species and grows well on Green Roofs.  The plant will enter a dormant stage during cold winters though and should be only one of the many native species comprising a native plant based green roof design.

Milkweed when blooming provides vibrant colors to a green roof planting scheme.
Monarch Larvae Feeding on Asclepias

Furthermore, native plant species tend to be more adaptable to the harsh conditions of a green roof, more so than many non-native or monoculture type landscape plants.

Wildlife are immediately attracted to green roofs with native plants.

Gulf Fritillary Butterflies Flying to Reach Green Roof Flowers

Gulf Fritillary Readily Forages on Green Roof Plants

 The saying, 'You Build It and They Will Come' is true with respect to green roofs, native plants and wildlife.

Over the years we have witnessed green roofs attract tree frogs and lizards initially, along with other smaller species.

The initial influx of lizards (we call them anoles in Florida) and tree frogs promotes a form of integrated nature-based pest management.  The lizards and tree frog devour pest insects like flies, termites and roaches.

Soon, larger animals such as birds and snakes arrive to forage on the lizards and tree frogs.

Not surprisingly, after the snakes arrive so do raptors such as hawks, kites and eagles.

You build it and they will come.

Yet not only do green roofs promote biodiversity by providing habitat for native and endemic species and also provide communal and foraging habitat for wildlife, they also provide another very important function with respect to endangered wildlife.

Cuban Tree Frog, Osteopilus septentrionalis
One of the fiercest and most invasive wildlife species in Florida is the Cuban Tree Frog, Osteopilus seeptentrionalis.

The Cuban Tree Frog has a voracious appetite.  One of its favorite prey is the native American Green Tree Frog, Hyla cinerea.

Hyla cinerea needs vertical green - greenery growing above 2 meters high to escape the larger, slower, heavier Cuban Tree Frog.

Green Roofs provide a refuge, a place of escape and safety for the American Tree Frog.

Biodiversity, habitat for plants and wildlife, carbon sequestration, oxygen production are all benefits of plants growing on the rooftop.

TPO and other innovative and eco-friendly roof materials cannot provide all vegetated roofs give.

Biodiversity may be the real reason Green Roofs are remembered in the future.

Remember.  No monocultures on a green roof.  Think native plants.  Think lots of native plants. 

As always, Happy green roofing!


Friday, January 21, 2011

Top Two Green Roof Design Issues

 Light availability is the most important green roof design issue.  Without light photosynthesis does not occur.  Without photosynthesis plants do not grow.  The green roof plants must have sufficient light levels for  the Calvin Cycle to occur, turning CO2 into complex carbohydrates for energy and growth.

Yet what is the second most important design factor in creating and ensuring survival in green roofs?  For extensive roofs designed to be employed in dry and arid climates using primarily C3 and C4 plants, the secondary most important green roof design factor  is Wind Exposure.

Rooftop permaculture
The above photo is a rooftop trial bed of winter salad mixes (the plants were started from plugs and are approximately 2 months old).

The green roof system is an extensive system consisting of a Colbond mat, a root and water barrier layer, a high organic content (compost based) yet well drained soil and the plants.

The system is partially surrounded (enclosed) on the primary windward side by a fog and dew catcher. The dew catcher is a woven fabric and allows approximately 80% light penetration and reduces wind flow by approximately 75%.

As you can see, the plants protected from primary winds by the fog catcher out-preform those subject to direct wind exposure.  In fact those protected plants have shown an approximately 300% increase in biomass production.

The plants are a mixture of those possessing C3 and C4 photosynthesis capabilities.  In this trial there was no significant difference in biomass production for the wind sheltered plants based on photosynthesis metabolic types.

Placing an anemometer around green roof system revealed an almost continuous daylight hour wind source from the east and northeast with average speeds running 3.5 Miles Per hour or 1.5 Meters Per Second .  A good source for average wind speeds in U.S. cities is available through NOAA.

Understanding of wind exposure is best gained by standing on a roof.  Rooftop ecosystems are manifestly exposed to significant and continuous winds, much more unprotected than ground level gardens.  If you have never stood on a roof you cannot imagine how much more wind flow exists five to ten meters above the ground.

Wind stresses the C4 and C3 plants through desiccating actions, stealing vital fluids from the mesophyll and interstitial layers just beneath the leaf's surface, slowing photosynthesis.  Stomata begin to remain closed, throttling the intake of CO2 and bringing the Calvin Cycle to a halt. With the inhibition of photosynthesis the plant biomass production also decreases.

C3 plants suffer the most.  Plants with C4 metabolisms however show somewhat more growth potential under wind-stressed conditions albeit not much.

So what does this mean?

It means afford wind protection to your green roof.  Understand that if your green roof has a wind exposed area then the green roof plants will suffer desiccation.

For flat roofs, parapets, research has shown,  serve as excellent wind breaks and can effectively reduce wind exposure by as much as 90%.

On exposed sloped roofs CAM plants can serve as wind breaks - remember CAM plants generally keep their stomata closed during the day anyway.

Adding more fertilizer or more water wont solve the problem.  Look to the wind.  Understand your sites wind directions and intensities.

Your green roof will love you for wind design consideration.

Finally, on a personal note, at first I would have thought water was the second most important design factor after light levels.  But we have found wind to have more significant influence on plants than hydrology.  However rooftop gardens and green roofs are ecosystems and it is not easy to fully separate the forms and interactions comprising the complex web of life forming a growing greenroof.

Wind issues are critical because they limit water.

Happy Green Roofing!  And as always, email your questions or comments.


Thursday, January 20, 2011

Green Roof Cations, pH, Garbage Bags, Trace Minerals and Compost (All for Free)

Free Compost, Cations and pH tools
Not too glamorous yet very practical ( remember Louis Sullivan and functionalist architecture) collecting your neighbor's bagged up yard leaves can benefit your green roof and benefit your wallet.

Cation exchange capacity and pH are two important variables of a green roof.  Additionally, leaf compost can add valuable trace minerals needed by the rooftop plants.

Leaf compost typically contains twice the amount of trace minerals by weight as does horse manure.

And heavy duty garbage bags are expensive.  We used to pay about ten US dollars per box at our local home improvement store.  Now we have all the free heavy duty garbage bags we need.

Interestingly, leaves from different species of trees offer varying characteristics.  While ash leaves are relative neutral in pH, some maple species leaves are documented to possess a pH of around 4.5.

Research shows use of properly composted leaves greatly increases the cation exchange capacity of soils.  One of the important functions needed in green roof soil media is cation exchange capacity.

Save $10 per month on garbage bags
 Though varying opinions of organic compost value to green roofs exist throughout the industry, many believe organic material in the soil media is highly beneficial to green roof plants.

Remember, green roofs are individual ecosystems, intricate webs of life with complex interactions.

Flat roofs with poor drainage may or may not require lower organic content to prevent water saturation and facilitate drainage.

Sloped roofs may function appropriately with high organic content.

Collecting heavy duty garbage bags filled with fresh raked leaves (we avoid those lawns heavily treated with fertilizers and herbicides/pesticides - those lawns are easy to spot here in the US due to the small advertising signs the lawn companies stick in the lawn after a fertilizer application - and speaking of lawns and fertilizers - a short must-see video of the history of the American Lawn will have you rolling in your chair and scratching your head at the same time can be viewed here) is a positive step for the environment.

Other benefits include;
  • Free highly effective cation exchange capacity supplements from the leaf compost
  • Free organic matter from the leaf compost
  • Free trace minerals from the leaf compost
  • Free pH adjustment material from the leaf compost (this is especially important when using higher pH soil media or media high in calcium)
  • Free garbage bags
  • And a lesson to your children riding with you to scavenge that recycling is more important than pride. :)
Enjoy the photos of the free leaf compost we gathered last week and also the free heavy duty garbage bags and as always - Happy Green Roofing!


Tuesday, January 18, 2011

Planting Green Roofs with Native Species for Biodiversity

Green Roofs are great places for all types of plants.  Food grows well on a roof.  Wildflowers grow well on rooftops.  Native grasses thrive on roofs.  Succulents and cacti readily adapt to rooftops.

Creeping Mimosa, a Florida Native, Mimosa microphylla

Many nurseries now grow a wide variety of green roof plants.  Some of the larger green roof plant growers include;

and many more  (we are working on compiling a complete list).

Yucca Filamentosa, Native Green Roof Species
Importantly, the use of endemic plants and native plants in green roof design is growing in popularity for many reasons including,
  • Water conservation
  • Biodiversity
  • Providing much need native habitat for wildlife
  • Providing a place for endangered plants to grow 
  • Preservation of endemic plant DNA pools
  • Providing native seed source helping in the fight against exotic invasive species
Moreover, many grassroots efforts are underway within communities to educate the populace about the benefits of planting native wildflowers.   Many good wildflower blogs are available online.  A few of these native plant blogs are;
  • Loret with Loret's BlahBlah Blog commented recently on the use of two Florida native plant species, Agave decipiens and Lespedeza capitata.

Both these species can be grown on green roofs with success, especially when planted as partner species.  The native agave provides a windbreak and shade to the clover while the clover provides NH3 and NO3 as fertilizer to the agave.

Click here for images of;
I would also add another excellent green roof native plant species (for Florida).  Yucca filamentosa, Adam's Needle is another proven green roof native plant species.

When choosing a green roof plant consult with a local horticulturist and discuss the different plant species appropriate for the site's ecosystem.  Consider native plant species as appropriate choices to encourage biodiversity, conserve water and provide habitat.

Green roof planting design do not have to be exclusively native or non-natives.  Native species may be integrated into any standard green roof planting design.

However, with the many ecological benefits native plant species can offer our urban rooftops, it may well benefit all to look to wildflowers for the next green roof project plant design.

Saturday, January 15, 2011

Why We Need Green Roofs

Florida's forests and wetlands bountifully stretch across the state, historically providing an uninterrupted swatch of green to migrating birds and other wildlife.

The same holds true for many other states here in the US and other nations.

When Europeans first arrived in the new world tall forests of trees, vines and shrubs stood, having grown over hundreds if not thousands of years.

Slowly and persistently with population growth, the volumetric green became horizontal green.

Ardea alba, Great White Egret, Orlando, Florida
Working with my son Ruairi last year on his entry for the state history fair, I stopped in Deland to pick up a copy of a DVD documenting the cutting of Florida's great cypress forests.

One of the elderly volunteers told me the story of and showed me photographs of a cypress tree, Taxodium distichum, cut and laying in the swamp waiting to be chained to a steamboat and taken to the sawmill.  The cypress stump measured 25' (7.62 M) in diameter.  The tree required three or four thousand years to grow and one week to fell.

Of the hundreds of thousands of acres of ancient native longleaf pine and cypress trees stretching across the state, all but two or three were logged.  Two ancient cypress trees, named 'The Senator' and 'Lady Liberty' are preserved in a small Seminole County Park, each several thousand years in age.

With the forests gone and wetlands filled, concrete and asphalt spread across the landscape.

Today, wildlife and birds no longer have uninterrupted corridors for travel and like the Ardea alba illustrated above resort to the concrete.

Mother nature though is resilient.  The egret was a juvenile, a youngster maybe six months or so old but was making the best of the urban jungle.  Finding a fast food restaurant and the left over fries, the bird seemed happy.

Plants across the roofs of Florida, the US and the world could never replace the forests we've cut.  But they could however serve to provide a level of habitat now missing in the cities.

Green roofs have been touted as energy savers.  I believe their real value is in restoring volumetric green back to the urban core.  Once green roofs appear then habitat is found, stormwater cleaned, a sense of place created, carbon is sequestered, food can be grown, community is strengthened and fresh oxygen replaces smog.

And tree frogs and lizards will be a healthier snack than the fries for the egret.

Happy Green Roofing!


Thursday, January 13, 2011

Manatees Gather at Blue Springs, Green Roofs Can Help Keep Florida's Springs Clean

Spring Run - Blue Springs to St Johns River
Today's fun topic is about the West Indian Manatee (Trichechus manatus).

What do Manatees have to do with Green Roofs?  Read on and you will find out.

While it has been an unusually cold winter with lower than normal air temperatures, Florida's springs usually stay approximately 67F (20C).

With the colder temperatures, the rivers cool too.

Because the West Indian Manatee (Trichechus manatus) is a mammal, they are warm blooded and need warmer waters to survive.

So in the winter when the river temperatures plunge, the manatees seek out the constant temperatures of the springs.

Now 67F (20C) is not warm - on a hot 100F (38C) summer day there is nothing better than a jump into the 67F cool waters of a Florida Spring.

West Indian Manatee (Sea Cow or Mermaid)
Florida has a wealth of springs.  Because most of the underlying rock is limestone and much as been eroded into underground caves and tunnels where cold, clear water flows.

Some of these underground tunnels filled with cold, clear water discharge at the surface, creating a 'spring'.  The water flows from the cave, out of the spring and down to a river or lake.

The water is clear, but note the yellowish tint
Florida has over 700 large freshwater springs.  For more information on springs from the FDEP website click here.

Limestone is eroded by water acidified through CO2 in the air.

Green roofs help to preserve Florida's springs and winter habitat for the West Indian Manatee by providing two benefits, including;

Momma and Calf

1. Green Roofs remove CO2 from the air, sequester carbon and produce oxygen, keeping the limestone intact and preventing erosion of the springheads.

2.  Green Roofs remove nitrogen and other contaminants from rainfall.  Without green roofs, nitrogen, phosphorous and other contaminants found in smog and air pollution enter Florida's waterways.  Green roof plants adsorb the nutrients from the rainwater, filtering the runoff and keeping the ground water from building high levels of nitrogen and other contaminants.

Look closely, hundreds of manatees line the far shoreline
Florida's springs have always had clear water.  That is until ten years or so ago.  Now we are seeing more and more springs exhibit the greenish and yellowish tint symptomatic of algae blooms feeding on increased dissolved nitrogen levels.

Green roofs can help stop the nutrient problem and clean groundwater, lakes, springs and rivers.

Green roofs can provide a safe and clean refugee for the West Indian Manatees.

As always, email your questions or comments.

Happy Green Roofing!


Wednesday, January 12, 2011

Green Roofs For Fun & Food & Learning - Garlic Boards!

Kevin's Florida Green Roof Garlic Board
OK - its not the highest tech approach to trying out new systems on a green roof but it is an approach I've used for years and it works!

Place a small 'pilot-plant' or 'test-unit' on the roof and see if the plants thrive or if the plants die.

Here is the sustainable Garlic board.

Sustainable because though this example is cedar, the board can be made of pine (potentially sustainable) or of bamboo (even more sustainable).

What does this really have to do with green roof?  Sure, it may be small scale permaculture on the roof but it doesn't have a water proofing system or root barrier system and one can imagine what kind of missile the contraption may become during 130 mph winds of a tropical cyclone here in Jacksonville - though the last really large hurricane to hit Jacksonville was Hurricane Dora in 1964.  Yet Jacksonville was hit by 18" ( 450 mm ) or heavy rain in 2008 by Tropical Storm Fay - if you are interested in seeing a video I shot during TS Fay of how 60 mph gusts only ruffles the tops of green roof plants - click below.


We'd take the board off the roof if a hurricane was approaching.  Thankfully, hurricanes or tropical cyclones give at least a couple hours notice or more now thanks to NOAA and other weather watch services.

However hurricanes are not the focus of this post.

The board is a statement of sustainability.

The garlic board is a first step in a process.  A process of moving away from synthetic materials to more natural materials for green roofs.  Surely there will be hundreds, if not thousands of other trial materials in our search for green roof sustainability.

We also purchased a roll of burlap from the hardware store this week and it too will be somehow fashioned into a type of 'garlic board' and tested.

Joanie Regan, the stormwater manager for the City of Cocoa Beach, has always told me that she is wary of putting 'plastic' into the ground.  She refers to the many stormwater systems available on the market made from polypropylene and other relatively stable petrochemical based stormwater products.  Her statement has resonated with me over time.  I keep thinking that I should be wary too, of installing layers of 'plastic' on roofs to create natural habitat.

Our collective intelligence as humans across the globe is so great that maybe if we throw out an idea, the idea will catch hold somewhere and grow.

The idea of developing a natural materials based green roof is growing in my mind and the garlic board is just one small step towards the idea becoming reality.

And the garlic board is working.  The cloves are sprouting now and hopefully will grow and fill out the deep wide holes drilled into the board under the trough filled with soil visible in the photograph.  Certainly the garlic is up high enough in the air to enjoy the bright sun's rays and the system is soaked with morning's dew on some mornings.

So we will watch the garlic cloves and learn something about cellulose as a platform for growing plants on roofs.

Having worked hands on with plants for over thirty years I believe there are approaches to take in developing and growing large mats of root interwoven plants that would hold themselves together on a green roof.  Though wood and burlap and other natural materials may disintegrate over time, they may provide enough of a structural system to allow the plant roots to develop into a sustainable structural system themselves.

Coir may be another sustainable material for green roof system establishment.  Potassium, salt and other limiting issues with coir can be resolved with pre-treament and maintenance procedures.

The approach we are discussing here would be relevant to green roofs with a primary function of habitat creation, food production, O2 production, carbon sequestration, urban heat island effect yet may present problems with green roofs constructed primarily for stormwater issue resolution.

Though a topic for another blog post, green roofs created for stormwater attenuation will probably need to be constructed out of a long term stable material.

True sustainability is what we all strive for.

I may never stop using woven plastics such as polypropylene or polyethylene, especially if they are made from post-consumer recycled plastics - might as well use up the scrap and they do hold the roof plant material together quite effectively.

However we are in peak oil, plastics are petro-based and I am a dreaming product of the post-hippy 1970's plastic junk inundation era.

I do want to make a long term difference.

And maybe the start lies with what I will learn from a cedar board on a roof with allium plants.


As always, email your comments and questions.

Happy Green Roofing!


Tuesday, January 11, 2011

Green Roof Plants - How Do I Choose? Quick Tip #7 Look Up!!!

Boston Fern, Nephrolepis spp.
I shot these photos on a walk the other day.  The show plants growing in gutters and out of crevices in other plants.

Why is this important?

Because it allows the green roof designer an insight into what plant species readily and successfully grow in the area without additional irrigation or fertilization.

Pine, Pinus spp.

Catbrier, Smilax spp.

Asparagus fern, Asparagus spp.
You may or may not choose to use one or all of the plants you see growing in gutters or on the roofs of buildings in your area.

You may though find surprises in the plants growing across the asphalt and concrete canvas framing your city.

The plants photographed here include;

  • Catbrier, Smilax spp.
  • Pine, Pinus spp.
  • Boston Fern, Nephrolepis spp.
  • Asparagus fern (an invasive species here in Florida), Asparagus densiflorus
  • Several grasses and ferns and others
Always keep your eye open for plants growing atop buildings!

As always, email us with your questions and comments.

Happy Green Roofing!


Monday, January 10, 2011

Green Roofs Help Clean and Attenuate Stormwater Runoff

Roof Drains, Jacksonville, Florida
The photos here are of a commercial facility adjacent to a hospital on Beach Blvd. in Jacksonville, Florida. 

The commercial facility has a large flat roof with stormwater runoff collected in the gutters and directed towards a ditch running through the hospital then down a larger creek/ditch directly into the St. Johns River and out into the Atlantic Ocean.

Roof Drains send water into the St. Johns River
The technology shown is no different that the gutters and ditches we see in excavations in old cities of the Roman Empire.

We've had well over 2,000 years as a civilization to think about our water resources and the way we treat stormwater.

The bad news is our rivers, lakes, streams and oceans have become more and more polluted.  Here in Jacksonville the St. Johns River becomes filled with green algae every summer due to the high nutrient loading in stormwater runoff.

The nutrients are primarily from residential and commercial lawn care and application.  Smog and air pollution is another source of nitrogen, one I refer to as another form of 'slow release fertilizer' becuase the smog deposits on roofs and is washed into adjacent waterbodies during a rainfall event.

The photo depicted here is of the Caloosahatchee River in Florida. 

Though the Caloosahatchee is not representative of all the rivers in Florida, it is however representative of a serious problem we have in Florida - that of nutrient runoff into our waterways.

The good news is Green Roofs can help to reverse the nutrient runoff problem by filtering atmospheric nitrogen and other nutrients from stormwater runoff, sequestering carbon and removing particulate matter that phosphorous may bind with.

Green roofs must take the lead and add zero additional fertilization to our ecosystems.

Green roofs must be designed to survive on atmospheric nutrients, leaf litter and detritus from the green roof plants and adjacent sources, bird feces and other natural sources of fertilization.

To be sustainable, green roofs must not use broadcast type fertilizer applications, fast or slow release.

Green roofs are about being eco-friendly.

The good news, again is green roofs can provide a solution.  Green roofs can:
  • Filter and clean stormwater
  • Provide much needed habitat for wildlife
  • Provide habitat for rare and endangered plants
  • Sequester Carbon, Nitrogen, Phosphorous and othe pollutants
  • Provide Oxygen and clean SMOG
  • Provide beauty to the asphalt jungle
Green roofs are one of the 'Green' answers to the global water quality crisis.

As always email your questions or comments here.

Happy green roofing!  Kevin

Friday, January 7, 2011

Green Roof Plants, C3? C4? CAM? and OMG! Fertilizers!

We are still discussing the difference between C3, C4 and CAM plants for green roofs.  Today's blog article is very simple but carries a very important message.

C3, C4 and CAM plants all have different metabolisms so they grow and add biomass at different rates.

Why is this maxim important?

Because no matter how much fertilizer you add to a C4 or CAM plant they may not grow as fast as a C3 plant grows.

In haste to make the green roof plants grow quickly and provide roof coverage, additional fertilizers are sometimes added (the magic potent) to encourage more biomass growth.

If the green roof is planted with C4 and CAM plants and heavily fertilized, the green roof plant growth rate will probably not be as fast as an unfertilized planting of C3 plants.  Adding more and more fertilizers may even kill the plants.

Some may feel there is comfort in adding fertilizers to a green roof.  The small, round little pellets impart a sense of 'doing more than one has to' to make the green roof grow.  In fact, adding fertilizers is truly 'doing more than one has to'.

Green Roof Fertilizer Runoff, Algae on Concrete
Fertilizers contain nitrogen and phosphorous, nutrients the plants use to grow.

However we need to remember these nutrients may run off the green roof during storm events and feed algae in local waterways.  Here in Jacksonville the St. Johns River becomes green with algae blooms as a result of fertilizer runoff.

Dead fish can litter the banks of the river due to the river's algae blooms.

Green Roof Fertilizer Runoff, Algae on Concrete
Understanding that C3 plants grow faster than C4 and CAM plants allows the green roof designer to specify appropriate fertilization applications appropriate for the species of plants.

The included photos here show a tale-tell sign of excess fertilizer or nutrients running of the green roof, encouraging algae growth across the concrete walls.

Like infra-red signatures for water leaks, the green stains of algae are a 'spot-on' indicator of the presence of fertilizer and other nutrients.

Remembering  C3, C4 and CAM plants all have different metabolisms and grow and add biomass at different rates will help reduce nutrient and fertilizer loading into our waterways.

Work with your local agriculture information staff to pick the right fertilizer for your green roof plants.  Spot fertilizer application is best and can be customized to the types of plants and where they are planted on the green roof.

Broadcast fertilizer applications are not recommended because no matter how much fertilizer you add to a C4 or CAM plant they may not grow as fast as a C3 plant grows.

Unless the green roof is a permaculture or food roof I recommend designing a nature irrigated habitat-type green roof and specifying the vegetation to take advantage of the natural nitrogen and phosphorous content in rainfall, supplemented by biomass from the roof leaf litter, bird feces and other natural sources.   These natural sources still contain nutrients for algae to feed on, but may be more manageable.

The simple message is this, do not broadcast fertilize a green roof.  One size does not fit all.  Finally, be sure to scrub the algae off the concrete if you do fertilize using an eco-friendly cleanser and not bleach.

As always, email your questions and comments here.

Happy Green Roofing!