Agave shawii aka Coastal Agave

Agave shawii is Shaw's agave, also called coastal agave. This succulent stores water and stays green all year. It belongs to Asparagaceae, the asparagus family. Its native range spans southern California and Baja California, Mexico. It grows in scrub and chaparral along the Pacific coast. Wild plants grow on coastal bluffs and mesas, or flat-topped hills. They also grow in the nearby foothills. Oregon State calls it rare in southern California.

The plant grows at a slow pace. Its leaves form a basal rosette, a ring at ground level. Garden rosettes reach about 3 feet [0.91 metres] tall. They spread about 4 feet [1.22 metres] across. LLIFLE reports wider rosettes of up to 4.9 feet [1.5 metres]. Offsets, or new shoots, grow around the base. These form small groups of plants. The upright green leaves have a broad, egg-like shape. They reach about 1.7 feet [0.51 metres] long. Hooked red spines line the leaf edges. A stiff, sharp spine also tips each leaf. The spines make the plant hard to handle.

Mature rosettes bloom from February to May. Plants may take 12 to 30 years to flower. Each rosette grows one tall flower stalk with branches. Missouri Botanical Garden gives its height as 8–12 feet [2.4–3.7 metres]. Oregon State reports stalks up to 13 feet [4 metres]. Flowers grow in tight groups on the side branches. They come in yellow-green, yellow, and reddish shades. The blooms draw hummingbirds and butterflies. Fruits range from oblong to egg-shaped and hold small black seeds. The rosette dies after it blooms. Its offsets can keep growing.

Grow this agave in sun and soil that drains well. Some shade may help at hot inland sites. It grows well in dry, rocky or sandy ground. Once plants take root, they cope with drought. They need little water at that stage. Missouri Botanical Garden advises no extra water once plants establish. Oregon State warns that summer watering may cause harm. Sources differ on how much cold it can bear. Missouri Botanical Garden recommends USDA zones 9b–10. Oregon State lists zone 8. LLIFLE gives a cold limit near 27°F. It also advises keeping plants out of hard freezes.

This agave suits rock, desert, coastal, and low-water gardens. It grows in pots, too, with leaves all year. Its resistance to deer adds to its garden value. Missouri Botanical Garden reports no major pest or disease problems. Wet or heavy soil can cause root or stem rot. Keep the sharp leaves away from paths and driveways. The supplied sources give no food or toxicity facts specific to this species.