Agave attenuata aka Elephant's Trunk

Agave attenuata, or foxtail agave, stays green all year. It is a succulent, with fleshy leaves, and lives for years. It belongs to Asparagaceae, the asparagus family. It comes from central Mexico, including Jalisco and Michoacán. Wild plants grow in small groups on rocky slopes and cliffs. LLIFLE says the species is rare in the wild. Its broad leaf rosettes give it a bold, rounded shape.

Garden plants reach about 3–5 feet [0.9–1.5 metres] tall. Reports give spreads of 4–8 feet [1.2–2.5 metres]. New shoots, called offsets, root at the base, forming larger clumps. Thick, curved stems can branch as the plant grows older. Old leaves fall off, showing the smooth, grey stems. The soft, fleshy leaves reach about 2.3 feet [0.7 metres] long. They range from pale yellow-green to grey or blue-green. They have no edge teeth or sharp spine at the tip. Each leaf tapers to a point that can fray with age.

Plants may take about ten years to bloom. LLIFLE lists spring bloom; RHS says flowers appear in summer. Missouri Botanical Garden says the plant rarely blooms. A tall stalk bears pale green-yellow flowers in a dense raceme. This is a flower cluster along the stalk. The stalk bends down, then curves up again. Flowers open first on the lower part of the stalk. Seed pods follow the flowers. Small plantlets, called bulbils, can grow beside the flowers. Most rosettes die after they bloom, but LLIFLE says some survive. Offsets at the base keep the clump growing after a rosette dies.

This plant cannot withstand frost. Grow it in sun; some shade also suits it. Sandy or loamy soil must let excess water drain away. It copes with poor soil and drought. Regular water helps it grow well. Dry spells can shrivel the leaves; water helps them recover. Under glass, RHS says to give less water in autumn. It advises dry conditions in winter. Missouri Botanical Garden gives USDA zones 10–12; RHS rates it H1C. In colder areas, use pots and grow outdoors only in summer.

The rosettes suit borders, gravel beds and courtyards. They also suit group plantings in warm climates. Pots let gardeners keep the plant where winters are cold. Its leaves give it shape through winter, as they stay green. It needs no pruning, and offsets can make new plants. The cited profiles report few serious pest or disease problems. Scale insects may occur; slugs and snails can harm leaves. It has no spines, but it can irritate human skin. RHS says to wear gloves and protective clothes when handling it. Dogs and cats can suffer harm if they eat it.