Agave salmiana

Agave salmiana, sometimes called Salm's Agave, is one of the largest species in the genus. It produces abundant offshoots, requiring space to grow. Its rosette consists of large, slender leaves with a flexible habit, slightly undulate, and with the sharp tips curved towards the centre. These leaves are a beautiful dark green and bear spines along their length. Adult plants only flower after 15 to 25 years, producing a gigantic flower spike, after which the rosette dies. This allows the offshoots to grow in its place. Moderately hardy, it requires a sunny location and well-drained soil. 

Agaves belong to the Asparagaceae family (formerly Agavaceae), which includes more than 600 species and about twenty genera, many of which are ornamental (Yucca, Cordyline, Sansevieria, Nolina). Native to Mexico, Agave salmiana grows throughout the central part of the country. This large distribution area has led to the development of several botanical subspecies, mainly Agave salmiana subsp. salmiana and A. salmiana subsp. crassispina (both with long leaves and large growth), as well as A. salmiana var. ferox, recognisable by its aggressive spines and smaller size. The crassispina subspecies is the most common form in cultivation in Europe.

Like the widely spread Agave americana, Agave salmiana is a large species. As an adult, this perennial forms a clump 2.5 to 3m (8 to 10ft) tall and 3 to 3.5m (10 to 11 ft) wide. The rosette bears a rather delicate and flexible appearance. Its large leaves are obviously rigid, but they have a supple aspect with elegant undulations. They look like cobras stretching towards the sky, with their tips curved towards the centre of the plant. These dark green leaves have powerful dark red spines in their youth, which later turn grey-brown. In old plants, the spines soften and almost disappear. The leaves take on a gutter shape, with a V-shaped section. The two rigid lateral edges join at the end of the lamina to form a long dark brown spine of 8 to 12cm (3 to 5in), which is extremely prickly. Curiously, the developing leaves leave their imprint on the leaf below, creating quite decorative patterns.

This species is primarily ornamental because of its beautiful leaves, as its flowering takes many years to occur. After 15 to 25 years, the rosette finally produces a spectacular flower spike, which can reach up to 4m (13ft) in height. This spike bears large panicles of flowers about 6 to 7cm (2 to 3in) in size, densely packed in bouquets that are quite spectacular, with a slightly greenish-yellow colour. Monocarpic, this Agave only flowers once before dying, leaving space for the offshoots at its base.

Hardier than Agave americana, Agave salmiana can withstand brief frosts down to -10°C (14°F) or even -12°C (10.4°F), provided it is planted in well-drained soil. Stagnant water is harmful to succulent plants, as it intensifies the effects of freezing. Planting on a slope facilitates water drainage. While it is demanding in terms of drainage, it is accommodating in terms of soil type. Poor and dry soil suits it perfectly.

Thriving in hot climates, this Agave salmiana is ideal for bringing life to a dry bed. Plant it alongside other plants that thrive in dry conditions, such as Yuccas, which are decorative with their slender leaves and abundant flowering. Hesperaloe parviflora, also known as Red Yucca for its magnificent coral-red flower spikes, will also make a perfect companion. Opuntias or prickly pear cacti will also work alongside this agave. Many species have excellent hardiness, such as Opuntia engelmannii var. rastrera, which can withstand frosts down to -20°C (-4°F).