Florida Permaculture Plant for Living Walls, Florida Green Roofs and Backyards, Seminole Pumpkin, Cucurbita Moschata

One of my favorite vines this year is the Seminole Pumpkin, Cucurbita moschata. 

Florida Green Roof and Living Wall plant, Seminole Pumpkin (Permaculture Food)

An adapted garden wonder to Florida, the Caribbean and Latin American, this variety of pumpkin or squash is acclimated to the harsh, humid climate of the region. 

Unripe Seminole Pumpkin, resistant to pests

A fast grower who provides ample shade, Seminole Pumpkin makes a great end of summer living wall and green roof plant.

Florida Living Wall plant, Cucurbita moschata

Thriving on neglect and drought, Cucurbita moschata, is ultra resilient to squash vine borers and other pests.  Here she is used as a cover to our geese pen, providing a wall of privacy, security, shade and food.

Seminole Pumpkin creates a living wall and green roof for the Urban Farm fowl

When thinking of drought tolerant plants for tropical green roofs and living walls, they don't just have to be wildflowers.

Seminole Pumpkin is a heavy food producing plant

 Nature has provided us with some awesome  food plants who will thrive well in the permaculture garden and on the hot roofs and walls.

Florida Permaculture Plant for Living Walls, Florida Green Roofs and Backyards, Seminole Pumpkin, Cucurbita Moschata

One of my favorite vines this year is the Seminole Pumpkin, Cucurbita moschata. 

Florida Green Roof and Living Wall plant, Seminole Pumpkin (Permaculture Food)

An adapted garden wonder to Florida, the Caribbean and Latin American, this variety of pumpkin or squash is acclimated to the harsh, humid climate of the region. 

Unripe Seminole Pumpkin, resistant to pests

A fast grower who provides ample shade, Seminole Pumpkin makes a great end of summer living wall and green roof plant.

Florida Living Wall plant, Cucurbita moschata

Thriving on neglect and drought, Cucurbita moschata, is ultra resilient to squash vine borers and other pests.  Here she is used as a cover to our geese pen, providing a wall of privacy, security, shade and food.

Seminole Pumpkin creates a living wall and green roof for the Urban Farm fowl

When thinking of drought tolerant plants for tropical green roofs and living walls, they don't just have to be wildflowers.

Seminole Pumpkin is a heavy food producing plant

 Nature has provided us with some awesome  food plants who will thrive well in the permaculture garden and on the hot roofs and walls.

Rooftop Permaculture for Urban Core Food

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.

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.

Urban Rooftop Permaculture, Bringing Organic & Healthy Food to the Urban Core

"Gene manipulated corn fields feed people"

The above comment was a response this morning to one of my suggestions rooftop permaculture can help.  It is really sad because some truly believe this.

Fortunately - people around the world are beginning to grow their own food, on patios, in windowsills and on rooftops in the Urban Core.  I believe rooftop permaculture and vertical permaculture is well on its way to replacing the old and becoming the new frontier in volumetric and rooftop green.

Green Roof Rooftop Permaculture - Brassica

Green Roof Vegetables - Broccoli

The broccoli here were pulled from the roof garden this week.  We had the Brassica growing in 4" of light weight highly organic composted and very well drained soil on a 4/10 slope.  You can see just how the vegetables became with no additional fertilizers and zero pesticides and herbicides.


Understanding permaculture principles and integrating those maxims into rooftop gardens can pay off with substantial results.  Organic greens, which cost four or five dollars at the market can be grown in masse on a small roof plot from an inexpensive packet of seeds.
Unfortunately, large corporations view rooftop permaculture and the citizens taking the task of feeding themselves back into their own hands as a serious threat to profits.

But I reject the above statement that "Gene manipulated corn fields feed people" as the only successful approach.

Many people may want to eat GMO corn products.  Yet I believe a large portion of the population may not want to.

So I see a grassroots movement arising to support rooftop permaculture, one where common people can make nutritional decisions for themselves rather than having the State or a Large Multi-national Corporation do so.

Check out just how big the Brassica grew.  Look at the root architecture.  We planted them close together to brace against wind issues and ate the greens daily. The plants adapted to the 4" soil (100mm) dispelling the myths of need for deep dirt to grow.
ECHO, see http://echonet.org is a great resource for rooftop permaculture practices, tips and design guidelines from a cost-effective approach.

Our $2.00 worth of seeds provided a daily bunch of organic greens and broccoli tops that would have cost US $ 5 in the store for six months.  As I see it the numbers work out to be close to $1000 savings in food costs, not to mention the health benefits.  That is just for organic broccoli alone.  Add the collards, mustards, sugar snap peas, pok choy, turnips, potatoes, tomatoes and the benefit of fresh air and gardening companionship and one can easily see the economic advantage.

No thank you to GMOs and to the outdated, stale industry guru's that are old news.

Green Roof Root Architecture, Understanding Water Adsorption

Today brought the monthly watering of a 1/4" H2O for the Alliums.  Within a matter of hours they were bright green.

We've been working with Resurrection fern also - and I love this plant.  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.

Both of these plants, the Allium and Resurrection fern have unique root characteristics.

We call plant root structure by the name - 'Root Architecture'.

Green roof design has unique root structure and root architecture requirements.

Unless you have a huge potable water or well water source and are going to pump all that water up on a roof to keep plants up there watered, then your green roof plants need to be somewhat drought tolerant.

Certain root architecture patterns support plant acclimation to drought conditions better than others.

Remember, Florida's rainfalls usually are short, afternoon events of 1/2" or less and because rain generally occurs between the hotter months of the year - June - September, there is a tendency for it to evaporate quickly.

Except for hurricanes and tropical storms, rain events in Florida are usually over relatively quickly.

Meaning green roof plants have to scramble to grab the rain water.

Also recall, most green roof plants do not like wet roots (wet feet) so the soil must be well drained.

Proper green roof plant root architecture is crucial for providing a Florida extensive green roof plant with the advantages needed to survive a Florida vegetated roof.

Examine the diagram below showing the root architecture of a green roof plant raised in a one gallon standard nursery container and then a green roof plant raised on a green root mat.

The plant raised on the mat possesses 8 times the amount of Root-Rain surface contact area as the same size plant grown in a nursery container.

Green Roof Plant Root Architecture - Florida Extensive Green Roofs - MetroVerde

So when the afternoon 1/2" rainfall (13mm) event occurs and every drop is important - the green roof plant with the appropriate root architecture will sequester the most water.

More stormwater is captured, runoff is reduced, plants acquire necessary water volumes, plants have less of a tendency to uproot in high winds, and more.

Green Roof Plant Root Architecture is important to the success of a green roof.

Biomimicry for Green Roofs, Catching Dew with Plants

Nature offers the finest examples for us to look to when resolving green roof, or any other for that matter, issues.


Yucca, with hairs across the surface edges of her leaves is a highly efficient fog and dew catching plant.

Likewise, with waxy, tough leaves and CAM (Crassulacean Acid Mechanism) photosynthesis, she can serve as the perfect green roof edge wind-break perimeter plant.

Hairs on Yucca's leaf edges allow for fog and dew collection on the Green Roof

Especially relevant during periods of extended drought, dew and fog can add much needed moisture to a green roof.  Because yucca is effectively adapted to low annual rainfall areas we can learn much from studying her botanical physiology. 


Yucca biomimicry tells us high dew catcher surface area to air mass contact is most efficient for air water vapor to occur.

Many yuccas and agaves thrive in hot, dry, windy areas and make excellent choices for green roof plants.

Yucca filamentosa, Adam's needle is a favorite green roof plant of mine, reliably hardy in the freezing cold temperatures, evergreen, very drought tolerant, a dew catcher and the perfect CAM perimeter plant.

Florida's native yucca, Yucca filamentosa ready for Green Roof install

Planted in mass, Yucca filamentosa acts as a green roof parapet, allowing interior plants a more welcoming ecosystem for growing.

Yucca filamentosa also has long hairs growing from the leaf edges, allowing for water vaopr in the air to collect as the humid breezes flow across the plant.

Turbulence is another factor necessary to help drop the condensed air water vapor from the catcher to the green roof soil below.

Success of a nature irrigated green roof depends heavily on sourcing a steady supply of water through rainfall, fog, dew and even frost. Understanding biomimicry based green roof planting layout allows for important air water vapor collection.

Additionally, understanding the principles behind Agave's and Yucca's' water capture successes lie also in an understanding of air humidity. Humidity is the amount of water vapor in the air.

Humidity is an important source of irrigation for nature irrigated green roofs and is often present when rain is lacking. Humidity is often described in terms of ‘relative humidity’ and ‘dew point’.

Relative humidity is the phrase commonly used by weather reporters to communicate the percentage as the amount of actual water vapor in the air divided by the amount of water vapor the air could hold.

A relative humidity of 75% means air contains 75% of the amount of water vapor possibly held.

Dew point refers to lowest air temperature where water vapor remains in vapor form. Once the ambient air temperature reaches the dew point temperature the water vapor condenses into dew or liquid.

Dew and fog reference and collection resources available on the web include;

Fogquest.org is a great informational resource on capturing dew and fog
A Great & Fascinating design paper about dew catchers
Youtube video on dew catcher constructionAir humidity can be a significant component in the irrigation of any green roof system. Consider those months with lower than average precipitation and check to see if dew occurs frequently. Validate the average relatively humidity percentages.

Think of the times you have walked across a lawn in the morning to find your shoes soaking wet.

Research dew and fog collection websites. Look to the green roof plants you work with to see what species appear to accumulate dew.

Mimic nature. Mimic the Yuccas and Agavaceae.

Green Roof Plants, CAM Photosynthesis Minimizes Drought Effects

In prior columns we discussed how some cold tender CAM plants, such as many of the succulents, can be damaged by freezing temperatures.  CAM plants are called CAM plants because they possess a specific form of metabolism called Crassulacean acid metabolism.


I love to use the CAM plants on green roofs because they can survive very long periods of tropical and sub-tropical drought without much in the way of rainfall.
The CAM metabolic process helps succulents and other CAM plants survive in dry, arid regions by working to keep stomata closed during the day when high temperatures and hot drying winds.  If temperatures are high, the sun is bright and stomata are open the plants can rapidly dehydrate.  

CAM plants open stomata at night when temperatures are cooler and solar radiation minimal.  When stomata are open CAM plants take in carbon dioxide (CO2) and store the CO2 in their leaf cells.  Once the sun rises and temperatures increase, CAM plants close their stomata and take the CO2 absorbed from the evening air and begin photosynthesis, producing the substances the plant requires and also oxygen, O2.

An analogy I like to use in comparing CAM plants to C3 plants is thinking about the difference between a gas guzzling 1970's sedan as compared to a new hybrid-type car with a highly efficient engine.  The C3 plants' metabolism is like the 1970's V8 gas guzzler - they both take in lots of fuel, fire up quickly, get to where they are going/growing quickly but are inefficient with respect to fuel utilization.  In the 1970's V8 wasted, unburned fuel leaves the engine as exhaust.  In the C3 plants we see volatilization and evaporation out of the leaf of photosynthesis substances through numerous opened stomata.  Yet both get where they are going/growing - quickly!

CAM plants though are like the highly efficient hybrid electric/petroleum engine.  In addition to conserving CO2 and preventing desiccation by keeping their stomata closed during the day, they are also very efficient at uptaking and using nutrients like nitrogen.  Because a CAM plant's CO2 is limited, the plants have developed mechanisms to become ultra-efficient at nutrient utilization.  Little is wasted.

Because of CAM plants adaptations to hot, arid, dry and drought-like conditions, they make great green roof plants and have been used historically across Europe as such.

Interestingly, some plants like the sedums can switch back and forth between the C3 and CAM metabolic processes depending upon the amount of water and nutrients available in the environment.  This process is called acclimation and is very similar to what we may imagine a grizzly bear's hibernation may be like.

Sedums are considerably more cold hardier than many of the other succulents that are members of the Crassulacaea family and so are popular in colder climates as green roof plants.  Some sedums are so popular for use on green roofs that they have become pest plants, exotic invasive species displacing some types of native vegetation.

Several CAM plants (Agave) surrounded by C3 plants

However, though CAM plants are excellent at surviving heat, aridity, and bright solar radiation and frost if protected, another climatic condition often is a limiting factor.  Though CAM plants, if protected can survive freezing temperatures and certainly can survive long periods of drought, many are susceptible to humidity-heat combination related issues.

Sedums and other succulents are highly prone to fungal attacks during the summer months when the temperatures range between 90 F and 100 F (35 - 37C).

The Southern Blight fungus, Sclerotium rolfsii, also known by the common names 'crown rot' and 'white mold' can decimate a well established roof of succulents or sedums.  Fortunately, southern blight does not seem to bother the succulents during cooler or dryer months.  However the everyday rainfall and resulting high air water vapor combined with high temperatures found during the summer months produce an environment just right for Sclerotium rolfsii, to proliferate.

CAM plants (Graptopetalum) with C3 and C4 Green Roof Plants

But what does all this technical information about photosynthesis and botany have to do with green roofs?

For the nature irrigated green roof, an understanding of C3, C4 and CAM plants and their advantages and disadvantages, their benefits and their limitations, is critical for a successful design.

Green Roof Succulent Injured by Southern Blight

As we continue our discussion of C3, C4 and CAM plants over the next several days we will begin to clearly see how 'Right Plant, Right Place' is important even on green roofs.

Water supplies are limited across the world.  We cannot continue to rely on irrigation use of potable water on landscapes or green roofs.

Designing a nature irrigated green roof will require utilization of a combination of C3, C4 and CAM plants, planted on the roof according to a number of biophysical variables we will discuss.

And so, to date we now understand that CAM plants are ideal for arid, hot areas and can survive drought.  We also know CAM plants may be susceptible to frost or also to fungal attacks encouraged by hot, humid weather.  We know C3 plants grow quickly.

Finally, as we discuss other important factors about plants suitable for a nature irrigated green roof we will begin to develop a sense of understanding as to the type of plant that will work long term on the green roof if planted in associations with other plants and in the right roof location.