Agave montana aka Mountain Agave

Agave montana, or mountain agave, is an evergreen succulent in the Asparagaceae family. It comes from the mountains of northeastern Mexico. Kew records it in Nuevo León. LLIFLE also lists Tamaulipas and Querétaro. It grows in open woodland among oaks, pines and junipers. Its mountain home has cool, wet summers, with frost and snow in winter.

The plant forms one dense rosette and does not make offsets. Garden plants reach about 3.3–4.9 feet (1–1.5 m) tall and wide. LLIFLE records occasional widths of 5.6 feet (1.7 m). The broad leaves stand upright and narrow to stiff points. Their colour ranges from grey-green to dark green, sometimes with a pale coating. Reddish-brown teeth line the edges, and each leaf ends in a stout spine. Older teeth can turn grey. Pressed marks from neighbouring leaves leave clear tooth patterns on the leaf faces.

The flower stalk rises far above the leaves. LLIFLE gives a height of 11.8–14.1 feet (3.6–4.3 m). RHS describes wild flower stalks reaching 16.4 feet (5 m). Short branches near the top hold dense groups of yellow flowers. Each flower measures about 2.4–2.8 inches (6–7 cm) long. LLIFLE reports that stalk growth starts in summer or autumn. Side branches emerge when warmer spring weather returns. The leaves may turn purple, red, orange or yellow during flowering. The rosette then dies, so growers raise new plants from seed.

Give this agave full sun and very free drainage. RHS recommends sandy, slightly acid soil in a warm, sheltered site. Under glass, use cactus compost and provide full light. Water well in summer, then reduce watering in autumn. Keep the plant dry through winter. RHS also recommends low-nitrogen feed three or four times during summer. It tolerates drought, but its seasonal water needs still matter. RHS rates it H4. LLIFLE reports survival at 10°F (−12°C), while warning that prolonged freezes can cause damage.

Its firm shape suits gravel gardens, courtyards and large patio pots. Growth is slow to moderate, and RHS gives 10–20 years to maturity. It needs no pruning. Scale insects may attack it, though RHS reports few disease problems. The sharp leaves call for care when placing or handling plants. RHS also warns that the plant can irritate skin. Wear gloves and other protective clothing when handling it. Keep it away from pets that chew plants, as eating it can harm cats and dogs.