Friday, March 23, 2012

Nature's Living Wall Plants

Every season brings a new face one of nature's finest display of living wall plants growing on the stone walls of Castillo De San Marco, St. Augustine, Florida.  St. Augustine is the oldest colonized city in the U.S. and plants have been growing on the hard shell facade of buildings here for centuries.  The fort is an educational paradise for any green roof or living wall designer.

Irrigated only with dew, fog and rain, the wall plants grow out of sheer vertical rock with little or no soil.

Wildlife are drawn to the diverse range of native plants in droves.

Native plants play an important role in supporting worldwide biodiversity heritage.

For a great blog post on just how important native plants are for supporting biodiversity, read the post here at Wildlife Garden.

One of the many ways to learn about native plants in your local downtown area is to 'look up'.  This week I again, spent several hours walking in the moat of the old Spanish Fort in St. Augustine.  In my opinion the National Park Service has it backwards - they charge for going inside the fort but allow you to walk for free in the moat and around the grounds.  The moat is where you can see many, many native and other plants species growing in the coquina walls!

Castillo de San Marco, St. Augustine

As you can see in the above photo, most plants grow underneath the downspouts on the walls.  Though the downspouts provide water primarily when it rains, they also collect dew and fog from surrounding areas and funnel the water to the plants.

Interestingly, learning about green roof and living walls plants from the fort offers insight into those plants that not only do well under the hot Florida sun and with no additional irrigation, but also the plants shed light on soil media composition.

Coquina shell and the limestome mortar have a quite high pH level.  High pH is usually one of the toughest issues to work with on green roofs and living walls.

Samolus valerandi
Florida Green Roofs: Pteris vittata & 2 Cuban anoles
Wildlife seeks out plants, especially those providing resource benefit such as food or nectar or shelter.  Native plants are best suited at providing the most optimum level of ecological benefit to those wildlife endemic to an area.

In otherwords, planting native plants on green roofs and living walls encourages and supports native populations of insects, birds, reptiles, amphibians and other wildlife.

Many popular landscape plants used on green roofs may not offer the same level of resource benefit.

Understanding natural systems through frequent field observations of your local native plants broadens design capabilities for both green roofs and living walls.

Floria Green Roofs: Limestone & Coquina Walls are Harsh Ecosystems

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