Tuesday, October 5, 2010

Plants for Florida Green Roofs - Root Architecture - Rain-Root Zone

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 R. 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.

Tomorrow - Actual photos of green roof plant root architecture styles.

Email me with questions by clicking here.

Happy Green Roofing!  Kevin

1 comment:

Parag said...

Green roofs have been in use since the Middle Ages in Europe, and sod roofs were a feature of pioneer homes in North America. After the oil crisis of the early 1970’s, Germany experimented with roof landscaping for energy conservation purposes. That country boasts more than 13 million square metres of green roofs.
Tips for green living