Tested Plant List
Sedum Album: 3 months zero-maintenance on roof
Sedum Album
Passed with flying colors. Ranked #1 overall. Changed to a beautiful red in winter.
Sun Hardiness: 5/5
Drought Hardiness: 5/5
Rooftop/Zero-Maintenance Performance: 5/5
Secum Acre: In shadehouse (with watering) after 1 year.
Sedum Acre
Fail. Died on roof due to lack of water after sustained lack of rain. Also doesn't block the weeds that well.
Sun Hardiness: 3/5
Drought Hardiness: 2/5
Rooftop Performance: 1/5 (Died)
D. Cooperi: 3 months zero-maintenance on roof
Delosperma Cooperi
Pass (Ranking #5). Although the plant loses its beautiful green color under stress, it still flowers on the roof in zero-maintenance conditions.
Sun Hardiness: 4/5
Drought Hardiness: 4/5
Rooftop Performance: 3.5/5
Herniaria: In shadehouse (with watering) after 1 year.
Herniaria Glabra
Fail. A surprise candidate, as this is not a succulent. This was placed in the shadehouse, but still thrived under low water and nearly zero maintenance. When placed on the roof, it lasted far longer than expected, but ultimately died.
Sun Hardiness: 2/5
Drought Hardiness: 2/5
Rooftop Performance: Fail (Died)
Green S. Japonicum: 3 months zero-maint. on roof
Green Sedum Japonicum
Pass (Rank #2). Needs to be hardened somewhat before placed on the roof, but after hardening performs really well. Forming a dense mat that sustains with zero maintenance on the roof.
Sun Hardiness: 4/5
Drought Hardiness: 4/5
Rooftop Performance: 4/5
Lampranthus after 6 months on rooftop zero maintenance
Lampranthus (Purple Stem)
Pass (Rank #3). Does exceptionally well on the roof after the plant has matured somewhat. Other forms of lampranthus don't seem to do as well as the purple stem variant. Only downside is the density, allowing weeds to break through (but that can change over time as it grows, or it can be compensated with supplemental Album/G. Japonicum)
Sun Hardiness: 4/5
Drought Hardiness: 4/5
Rooftop Performance: 4/5
Sedum Palmeri
Pass (Rank #6). Shrinks in size and turns more yellow when under stress, but it really hangs in there. Would look great with supplemental sedum.
Sun Hardiness: 3.5/5
Drought Hardiness: 3/5
Rooftop Performance: 3/5
Ruschia Lineolata Nana
Fail because the "Nana" variant of this is is a patented plant. If it wasn't patented, it would be a "Pass." This gives me sufficient evidence that I should benchmark the non-patented Ruschia Lineolata and see how it performs.
Sedum Sarmentosum
Fail. Seems to be dying off after 3 months on the roof. Looks like it needs more water.
S. Reflexium after 6 months on roof zero maintance
Sedum Reflexium "Blue Spruce"
Pass (Ranked #4). Totally hanging in there with zero-maintenance on the roof.