Friday, August 30, 2013

Green Roof Plant Design - Understand Heliotropism and Paraheliotropism

Understanding photosynthesis processes in green roof plants is crucial to the green roof designer and we have discussed the difference between C3, C4 and CAM photosynthesis processes in prior notes, including;
Under Intense Sunlight Leaves Fold to Prevent Desiccation



Yet nature is complicated and does not limit herself in resisting environmental stressor conditions to just the above three types of photosynthesis processes.  In fact, some plants have evolved other survival mechanisms to help prevent dessication and to conserve water, especially in arid and hot climates.

Some plants, and many of these are excellent species to use on Green Roofs, can move, open or close their leaves to prevent dessication.  This is commonly referred to heliotropism and paraheliotropism.

Cowpeas and other plants for example possess the ability to adjust their leaves position to either increase or decrease the amount of leaf surface area receiving direct sunlight.

Under optimal Sunlight C3 Leaves Open Widely

Under Optimal Sunlight Conditions C3 Leaves Open Widely
Heliotropism is the term used to describe a plant's actions when it orients leaves to receive more sunlight and thereby increasing photosynthesis capabilities, i.e. - more CO2 fixation.

Diaheliotropism describes a plant whose leaves actually track the sun'd path, maximizing solar contact.

Paraheliotropsim denotes a plants actions similar to the above photographs.  During paraheliopropsim, plants may fold or move their leaves to either;

  • Minimize solar contact, or
  • Minimize total leaf surface area,
either way reducing water loss and preventing desiccation.

Though C3 plants such as the beans - and most other of the world's food plants except the grasses, maize, and sorghum - do not possess as complicated a multi-cellular Calvin Cycle as C4 plants and are more susceptible to drought, they - through Heliotropism biomechanisms they do possess their own unique desiccation prevention mechanisms.

Green Roof designers take note!

Thursday, August 29, 2013

Florida Green Roof Plant Root Architecture - Think Lateral!

Florida Green Roof plant root architecture and the converse relationship to irrigation is an important design function for the Green Roof professional to understand.

We've been working with Resurrection fern as a Green Roof plant for Florida and the tropics - and I love this plant.  Resurrection fern,  Polypodium polypodioides, was the first fern we know of 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.

So think lateral.  Think horizontal.  Experiment with green roof planting designs that encourage outwards rather than downward root growth.

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

Tuesday, August 27, 2013

Green Roof Plant Selection for Tropical and Florida Green Roofs

Best Florida Green Roof Plant?

We are always working to find suitable plants for Green Roofs in Florida.  For years Northeast Florida has been experiencing a severe drought.  Finding the toughest and most visually appealing is only part of the process.  Habitat value, invasiveness, wind and drought tolerance are other issues we consider.

Green roofs in Florida are harsh places – remember the 7 (or more) H’s:
  • High Humidity
  • Hot, hot heat
  • High desiccating winds (killer)
  • Hurricanes (not the football team)
  • Hard Freezes
  • Horrible temperature swings
  • Hurtful droughts
  • Harmful floods

And we all are cautious about irrigating a green roof (I speak as a lawyer – not a botanist here) – our litigious society has already bred a number of legal articles on green building and tort.  Imagine – the issues of:
  • Mold
  • Water damage to interiors
  • Collapse from weight (water is heavy)
  • Bacterial breeding
  • and who knows what else…

So if we choose to acknowledge Florida’s water shortage problem and build a green roof with micro-irrigation or no irrigation at all, then we need to look to plants that:
  • Can survive the many H’s
  • Are visually acceptable by the community
  • May be cost-effective
  • Are preferably native species (or non-invasive species)
  • Do not present a fire hazard or contribute too much dry leaf litter
  • Are low maintenance
  • Can survive long periods of drought
  • Can survive twenty inch downpours
  • Resist fungal infestations
  • and much more

Five of the most outstanding plants that almost begin to come close to the above requirements are:
  • Frog Fruit, Lippia nodiflora
  • Wild Garlic, Allium canadense
  • Adam’s Needle, Yucca filamentosa
  • Lemongrass, Cymbopogon spp.
  • Purple Muhly Grass, Muhlenbergia capillaris
What works for you?


Green Roof Plant Dwarfed 2 Year Old Allium Canadense



Monday, August 26, 2013

Florida Green Roofs, Living Wall Permaculture Plant, Seminole Pumpkin, Cucurbita Moschata

Seminole Pumpkin should always be considered for tropical green roofs and living walls due to its amazing leaf color and massive summer biomass production.

Summer time here in Florida usually brings the rains.  Rains mean more water on the green roof.  Seminole pumpkin drinks water like a thirsty athlete.  She also casts a fair amount of sprawling shade to help cool the roof from solar rays, in addition to the evaporative effect of photosynthesis and plant respiration. 

So it is easy for me to say, 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.

Sunday, August 25, 2013

Living Architecture, Urban Hen Coop - Low Cost, Simple Design

Urban Farm Coop Frame
Out of the Archives - Here is our Urban Hen Coop Design that easily hed our 27 hens and doubled as a rabbit home, grape arbor and greenhouse.  Built out of scrap for almost nothing.

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One of the first tasks at hand we were faced with when starting an Urban Farm was the design and construction of a chicken coop.

With twelve newly hatched chicks growing rapidly each day we knew it would only be a matter of time before the puffy peeps would no longer comfortably fit in the large, blue tupperware storage bin.

I'd never built a coop before and honestly had no idea where to start.  The images we found on the internet were complicated looking, possibly requiring days of intricate cutting, nailing and screwing.

I'd just rather bang-bang get it done quickly.

But the coop had to look good and had to be functional.  Most of all the chicken pen had to be cheap.

Here is how we made our really cool, pimped out fowl parlor.

First we figured four square feet per bird, pretty much the standard for chickens as stated across the omniscient web.  Ten birds would be forty square feet - not a overly large area - but sufficient enough to let the chickens roam around in, chase bugs and roost at night.

Then we decided on the spur of the moment to quadruple the size to one hundred sixty square feet with no good reason except we wanted our hens to be happy hens.  Whether or not larger coops make happier hens remains to be seen.  But I am glad we have a large coop and the hens seem to enjoy chasing each other around the coop aggressively determined to rob whatever morsel of food one or another hen may be carrying in her beak.

Coop frames are the foundation on which the final coop appearance and function develops.  I like arches but don't want to have to bend pipe or purchase pre-bent pipe.  The coop walls also need to be critter proof.  below is a photo of a basic coop frame upon which living walls will be established.


The frame is inexpensively constructed with grey electrical conduit (Outdoor plastic type) that easily bends to create the arches.  The ends of the conduit are zip-tied to either farm fence posts or chain link posts hammered into the ground.  Finally chicken wire or fencing is added to the frame to keep critters out and fowl in.

The frame can be covered with a variety of native materials, such as bamboo or saw palmetto fronds.  We also grow native flowering vines and food plants around the coop for shade, visual effect and feed for the hens.

One year later our coop begins to blend into the urban farm fruit vines.

Grapes covering the Coop walls
Cost-wise we have less than one hundred dollars into a very large, hen happy chicken coop with all the reuse of scrap materials we incorporated.

Coop Door View Living Architecture