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Field guide
Century plant (Agave americana)
Wikimedia Commons

also American agave

Century plant

Agave americana

Family:
Asparagaceae
Elevation:
1,000 ft – 5,000 ft
Bloom:
Jun – Aug
Region:
Southwest

A massive blue-gray rosette of thick, spine-tipped leaves that can sprawl six feet or more, a dramatic architectural anchor in warm-desert landscapes. After many years it sends up a towering asparagus-like flower stalk, blooms once, and dies.

Care · tuned to the Southwest

Water

Extremely drought tolerant; deep but very infrequent water speeds growth in the first year or two, then essentially none is needed. Overwatering, especially in heavy soil or during cool weather, causes crown and root rot.

Sun & exposure

Full sun, including reflected heat off walls and pavement; can tolerate light afternoon shade in the hottest low-desert sites.

Soil

Wants fast-draining sandy or gravelly soil; tolerates poor, alkaline, and caliche ground. Avoid rich, moisture-retentive beds and standing water.

In the Southwest

Frost-tender: foliage is damaged by hard freezes and it is generally unreliable much above the mid-elevation desert. Monocarpic (dies after its single bloom) but leaves numerous pups. Leaves have needle-sharp terminal spines and saw-toothed margins; site away from paths and trim spine tips near walkways.

Common problems & fixes

  • Agave snout weevil — the rosette suddenly wilts and topples, with grubs and rot at the base

    Fix — Apply a preventive systemic soil drench in spring and dig out and destroy infested plants and grubs.

  • Crown and root rot from overwatering — the center softens and collapses in wet soil

    Fix — Plant in fast-draining soil, water sparingly, and keep irrigation away from the crown.

  • Aggressive pups and huge size overwhelm small beds

    Fix — Remove pups regularly and give it room, or choose a smaller agave for tight spaces.

Pets & toxicity

Sap contains saponins and calcium oxalate that irritate skin, mouth, and gut; ingestion can cause drooling, vomiting, and diarrhea in pets and livestock, and the rigid spines cause mechanical injury.

Easy to confuse with

  • Agave neomexicana — much smaller and notably cold-hardy
  • Agave parryi — compact, tighter gray rosette with shorter leaves

Sources

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