Purple-blue flower spikes rise above aromatic gray-green foliage in early summer. This sage, from Southern California and northern Baja, grows 3 to 5 feet tall, and 5 to 8 feet wide. Zones 8, 9, and 12–24.
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Photo by Drew Avery (via Flickr Creative Commons)
In the Southwest and Rockies, swap in Helictotrichon sempervirens (shown) for Libertia peregrinans.
Helictotrichon sempervirens: Thin, blue-gray blades of this Mediterranean grass grow in clumps that reach 2 to 3 feet tall and wide. Blond flower clusters form 2 feet above foliage in spring. Zones 1–12 and 14–24.
Rooftop gardens face special challenges: Since they’re constantly exposed to direct sunlight and wind, they demand super-tough, drought-tolerant plants. So if you’re looking for plants that’ll grow well in arid ground-level landscapes, a thriving green roof would provide plenty of inspiration.
Especially when that roof belongs to the much-lauded Margarido House, the first residence in Northern California to earn LEED-H Platinum certification. For this Oakland project, landscape designer Lauren Schneider mixed California natives that thrive in hot, dry conditions with plants that evolved in similar climates.
“I love the juxtaposition of the coarser and finer plant textures,” she says. “And I like to use the foliage colors as streaks and splashes.”