Agave xylonacantha aka Century Plant

Agave xylonacantha, or saw leaf agave, is an evergreen succulent perennial. It belongs to the Asparagaceae family and comes from northeastern Mexico. Its range includes Nuevo León, Hidalgo, and San Luis Potosí. It also grows in Tamaulipas, Guanajuato, and Querétaro. Wild plants grow on dry limestone slopes and in valleys. These sites lie on the dry side of the Sierra Madre Oriental.

The plant forms a loose rosette on a short stem. Some plants make offsets as they age. RHS gives a garden height and spread of 3.3–4.9 feet [1–1.5 metres]. LLIFLE describes lower rosettes, about 1 foot [0.3 metres] tall. These can reach 3.9 feet [1.2 metres] across. Plants take 10–20 years to reach full size, according to RHS. Each rosette has relatively few stiff, rough leaves. Leaf colours include green, blue-green, olive, and near-silver shades. A pale stripe runs along the leaf centre. Broad, flat teeth line the wavy edges like a saw. Each leaf ends in a stout spine.

Mature plants can send up a tall, upright flower spike. LLIFLE gives its height as 9.8–19.7 feet [3–6 metres]. Flowers grow in small groups along its upper section. Their tepals range from greenish tones to pale yellow. The main rosette dies after it flowers. Offsets offer one way to raise more plants. Gardeners can remove them in spring or autumn. Seed provides another means of propagation.

Give this agave sun and soil that drains well. It also accepts partial shade and sandy or loamy soil. Acid to neutral conditions suit it. Under glass, RHS recommends cactus compost and generous watering during growth. Keep it almost dry through winter. Feed with dilute liquid fertiliser three or four times during growth. Plants tolerate drought, but they do not survive freezing. RHS rates the species H2. In Britain, it needs a greenhouse or conservatory for winter. It can spend summer outdoors in a sunny spot. Light afternoon shade can help prevent scorch during very hot summers.

RHS suggests this plant for pots, patios, courtyards, and gravel gardens. It also lists coastal gardens and planting with a subtropical style. Its evergreen leaves provide interest beyond the flowering period. It needs no pruning, and disease problems are uncommon. Scale insects may attack it. Contact can irritate human skin, so wear gloves and protective clothing. The plant also harms dogs and cats if they eat it.