Green Roof plant modules: result in a instantly and well rooted plant mass.
This form of green roofing receives lots of good reviews; however, there are also horror stories.
The pictures below visualize a less preferred result VS a highly preferred result, both modular, yet the technology behind them explain why the left picture will never improve and why the right picture shows a healthy modular Green Roof.
A modular green roof system is often more expensive compared to the other types of plant systems, because all the care you would normally put into a roof based on plant mats or plugs, is put into the modules.
Green roof modules are ALMOST an install and forget method of applying a green roof. They still require care, but far less than when installing plant plugs or seeds. The difference is that plants in a modular green roof are well develop in terms of plant mass and are fully rooted into the growing media.
The initial cost differential between plant modules and plant plugs ore Sedum mats would be in the additional care these other systems require. a modular Green roof would require less frequent watering and rairly require plant replacment (what a Green Roof planted with plugs often require.
In the end, while a Instant Green roof System such as a modular system may cost more to install, they may be cheaper in the long run when you considering total cost of the materials and added care of other systems. The additional cost can be recovered in as little as 2 years of ownership
Comparing the left module to the module on the right:
The system on the left shows a carrier that holds only 1 inch of growing medium, resulting in a mono culture because of the harsh conditions and most plants die.
The system on the right has a carrier holding 4 or more inches of growing medium, where the carrier itself is less than 1/2 this high.
Properly Installed Modules May Be Your Best Long Term Investment!