Tough Plants: Recommendations from Alcatraz Gardens

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echium candicans

Pride of Madeira, or Echium candicans, thrives on the challenging Alcatraz Island.

Adapted from text by Shelagh Fritz for Horticulture’s January/February 201 issue.

Alcatraz, the maximum-security federal prison in San Francisco Bay, closed its doors in 1963, but it continues to capture interest and inspire works of fiction and non-fiction in various media. A surprising aspect of the island prison also persists to spur creativity: its cultivated plant life.

The plants, along with soil and water in which to grow them, were first brought to the barren Alcatraz Island around 1854, when it was used as a lighthouse station. A plant inventory conducted in 2005 revealed just over 200 species of plants coping with the island’s Mediterranean climate of dry summers and wet winters. The USDA places Alcatraz Island in Zone 10b, with low temperatures ranging from 35˚F to 40˚F. While these are mild temperatures, there is a near constant breeze. Meanwhile, 4,000 western gulls call the island home during their nesting season (February to September). It’s a challenging spot to garden, to say the least.

Here are a few favorite drought-tolerant, tough-as-nails plants at the Gardens of Alcatraz:

Pride of Madeira (Echium candicans): This rounded evergreen subshrub grows 4 to 6 feet or taller, with grayish green leaves and dramatic spikes of blue-purple flowers in spring and summer.

Iceplants: These southern African succulent groundcovers burst with daisylike flowers in late winter and spring. Favorites at Alcatraz include trailing iceplant (Lampranthus spectabilis), with magenta flowers; and rosea iceplant (Drosanthemum floribundum), with purple flowers that seem to glitter.

Fox-tail agave (Agave attenuata): This is a favorite agave because its wide, arching, pale green leaves lack a sharp tip. It grows 4 to 5 feet tall and wide.

Penstemon heterophyllus:A compact California-native beardstongue, it boasts a low, dense habit to 14 inches tall and wide. It covers itself with wands of electric-blue flowers in spring to the delight of hummingbirds and butterflies.

California fuchsia (Epilobiumcanum): This California native formerly known as Zauschneria bursts with red-orange tubular flowers in summer, when many other natives have gone dormant.

Echeverias: These sculptural succulents add color in or out of flower. Blue rose echeveria (E. imbricata) has low rosettes of smooth blue-green leaves that echo the colors of the sea; fuzz-covered E. pulvinata carries its leaves at the tops of rust-colored stems.

For a complete list of survivor plants and for xeric plants that we have used in the garden rehabilitation, see alcatrazgardens.org.

Image credit: Jeanette Sinclair