Best Florida Green Roof Plant?

Green roofs in Florida are harsh places – remember the 7 (or more) H’s:

1. High Humidity
2. Hot, hot heat
3. High desiccating winds (killer)
4. Hurricanes (not the football team)
5. Hard Freezes
6. Horrible temperature swings
7. Hurtful droughts
8. 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:

1. Can survive the many H’s
2. Are visually acceptable by the community
3. May be cost-effective
4. Are preferably native species (or non-invasive species)
5. Do not present a fire hazard or contribute too much dry leaf litter
6. Are low maintenance
7. Can survive long periods of drought
8. Can survive twenty inch downpours
9. Resist fungal infestations
10. and much more

Two of the most outstanding plants that almost begin to come close to the above requirements are:
1. Frog Fruit (Lippia nodiflora), and
2. Wild Garlic (Allium canadense)
I’ll be posting more data on these two species over the next couple days.  In the meantime – what are your experiences with these species on green roofs?

Green Roof Plant Dwarfed 2 Year Old Allium Canadense

Happy green roofing!   Kevin