Florida Green Roofs and Biomimicry, Agavaceae and Dew

Nature offers the finest examples for us to look to when resolving green roof, or any other for that matter, issues.  Today I want to mention plants that catch air moisture, such as dew, and help 'irrigate' a green roof.  Let's look at some of my favorite green roof plants, Yucca and Agaves.

Floria extensive, sloped green roof

Green Roof Plants, Yucca and Agaves - note the hairs and clover, a nitrogen fixer

Yuccas and Agaves, 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, they can serve as the perfect green roof edge wind-break perimeter plant.

Yucca and Agave 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.

Yucca filamentosa makes an excellent green roof plant for Florida

Planted in mass, Yucca filamentosa acts as a green roof parapet, allowing interior plants a more welcoming ecosystem for growing.  This green roof plant has not only survived, but thrived on some of our older green roofs!

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.

Florida Green Roof  Plants Yucca and Agaves, Note the hairs along the plant edges that facilitate dew sequestration

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.

Yucca acts as a dew catcher to provide moisture to other Florida green roof plants

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 

• Youtube video on dew catcher construction

Air 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.

Yucca filamentosa, Green Roof Plant for Hot, Dry and Arid Climates - Catching Fog and Dew with Hairs

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

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 construction

Air 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.

BioMimicry - Following Moss - Nature Based Irrigation for Green Roofs

Tillandsia usneoides

BioMimicry is the art and science of looking to Nature for answers as Nature over the eons has perfected many processes.

The plant shown above is Spanish Moss, Tillandsia usneoides, a Bromeliad.  Spanish Moss hangs ubiquitously from Florida trees, especially the Live Oaks, Cypresses, Longleaf Pines and Red Maples.

For green roof designers, adapting a bit of biomimicry based on Tillandsia usneoides can prove very useful.  You see, Spanish Moss feeds only from the air.  All the plants' water needs and nutrient requirements are met from scavenging the air.  Spanish moss utilizes host trees for support, hanging from the limbs and branches yet not penetrating the bark of the host tree.

As seen in the above photograph, Tillandsia usneoides is quite efficient at capturing atmospheric moisture.  Most mornings Spanish moss is covered in dew.  Following the principles of biomimicry, we can look to Spanish moss for dew and fog catcher design fundamentals.

Dew Catcher with woven fabric similar to Tillandsia usneoides

Dew is available as a primary nature-based irrigation component

Spanish moss biomimicry tells us high dew catcher surface area to air mass contact is most efficient for air water vapor to occur.  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. Using biomimicry based on Nature's Spanish moss design allows for important air water vapor collection.

Additionally, understanding the principles behind Spanish moss' 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 construction

Air 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 Spanish moss.


As always, feel free to email us with your comments and questions and Happy Green Roofing!


Kevin

Dew Catchers for Green Roofs - Nature's Irrigtion

Lots of information exists on creating air turbulence, humidity, condensation and collecting dew.

I'll post an article with links to more information soon however below are some photos of dew collection inspiration and then the actual construction and installation of a simple but effective dew catcher on a permaculture roofs - one with winter veggies planted.

As always - email your questions here and happy green roofing!

Kevin

Morning Dew is Often Everywhere

Morning Dew Collecting on Green Roof Plants

Designing a Green Roof Dew Catcher

Constructing a Green Roof Dew Catcher

Green Roof Dew Catcher Ready for Installation

Green Roof Dew Catcher Installed