Agave tequilana F.A.C. Weber (blue agave, tequila agave) is the plant behind the tequila industry. Commercial tequila is legally defined as a distillate produced from the cooked hearts of A. tequilana 'Weber Azul' grown within the denomination-of-origin zone that encompasses the state of Jalisco and small parts of Guanajuato, Michoacán, Nayarit, and Tamaulipas. 'Weber Azul' is a single clonal cultivar propagated exclusively from offsets; the industry rests on a narrow and genetically uniform base.
Taxonomically the species belongs to the subgenus Agave, group Rigidae, close to A. angustifolia (with which it is sometimes treated as conspecific in the broader sense). Habitat is volcanic upland at 1,200 m to 2,000 m, receiving summer rainfall and mild winters.
Part of the Complete Agave Guide.
Identification
- Leaves. Lanceolate, 90 cm to 130 cm long and 8 cm to 12 cm wide, strikingly glaucous blue-grey, and stiffly rigid. Margins carry small brown teeth 3 mm to 6 mm long, relatively widely spaced. The terminal spine is reddish-brown, 1.5 cm to 3 cm long.
- Rosette. Solitary to sparsely suckering, 1.2 m to 1.8 m across at maturity, with a short but distinct trunk developing after a decade.
- Inflorescence. Paniculate, 5 m to 6 m tall, with 20 to 25 lateral branches carrying greenish-yellow flowers. Under commercial cultivation the scape is cut before flowering so that sugars accumulate in the hearts; uncut plants flower at 6 to 10 years.
The most reliable field character for separating A. tequilana from A. angustifolia is the distinctive blue-grey leaf colour combined with the broader leaf width.
Cultivation
A. tequilana diverges from the pillar defaults as follows:
- Cold tolerance. Poor. Leaf damage at 0 °C and crown rot at −4 °C to −5 °C. In USDA zones colder than 9b it is a conservatory plant only. Published claims of hardiness for "blue agave" often refer to other blue-leaved species such as A. ovatifolia, not to this one.
- Light. Full sun year-round in any climate where it can be grown outdoors. Etiolates rapidly under glass if light is insufficient.
- Water. More tolerant of summer watering than cold-hardy agaves, reflecting its summer-rainfall habitat. Weekly watering in active growth is fine provided drainage is sharp.
- Flowering prevention. Ornamental growers rarely cut the scape, but be aware that flowering kills the rosette. For landscape plantings, remove emerging pups to maintain a single specimen, or allow a colonial stand to establish.
Propagation
Commercial 'Weber Azul' is propagated exclusively from offsets, and the same applies in cultivation. Seed is rarely used because the clone is essentially genetically uniform and compatible seed parents are absent. Sever pups once 20 cm to 30 cm in size, callus for a week, and pot up as per the pillar.
Bulbils form on the old scape if the plant is allowed to flower, but this is uncommon in ornamental cultivation because flowering is rare and the parent dies afterward.
Notes
The monoculture of 'Weber Azul' in Jalisco has been flagged by agronomists as a disease-vulnerability problem; because every plant in commercial tequila production is a clone, a single pathogen of sufficient virulence could devastate the industry. Sigatoka-like fungal outbreaks and bacterial diseases have been studied for exactly this reason. It does not affect ornamental cultivation directly but it is worth understanding the provenance of any A. tequilana you buy.
Outside Mexico, A. tequilana is most often sold under the trade name "blue agave", which is ambiguous and sometimes applied to A. americana var. expansa or other blue-leaved agaves. Check the label against the morphological characters above.
See also: Agave angustifolia, Agave americana, Agave vilmoriniana.