Agave parryi Engelm. (Parry's agave, mescal agave) is the most cold-hardy species in common cultivation and the usual choice for temperate-climate agave plantings. It is native to the high-elevation oak and pine woodlands of southeastern Arizona, western New Mexico, and northern Mexico, occurring between 1,500 m and 2,500 m. The species name honours Charles Christopher Parry, a 19th-century botanist of the western US.
Taxonomically it belongs to the subgenus Agave, group Parryanae, with close relatives A. havardiana and A. neomexicana. The group is defined by compact glaucous rosettes and exceptional cold tolerance compared with most of the genus.
Part of the Complete Agave Guide.
Identification
- Leaves. Broadly oblanceolate to obovate, 25 cm to 50 cm long and 10 cm to 18 cm wide, markedly glaucous silvery-blue, and stiffly rigid. Margins carry short dark teeth 2 mm to 5 mm long, and the terminal spine is dark brown to black, 2 cm to 4 cm long, often with decurrent lines of pigment running down the leaf surface from the spine base. These dark decurrent lines are a reliable identifying feature.
- Rosette. Compact, symmetrical, 50 cm to 90 cm across, distinctly domed in profile. Offsets form slowly, typically a few per decade in cultivation.
- Inflorescence. Paniculate, 3.5 m to 6 m tall, with 15 to 25 dense umbellate clusters of yellow flowers tinged red in bud. Flowering age in cultivation is 20 to 30 years.
Three recognised varieties exist: var. parryi, the nominate form; var. truncata, sometimes treated as a separate species, with shorter broader leaves and a more southerly range in Mexico; and var. huachucensis, with larger rosettes, endemic to the Huachuca Mountains of Arizona.
Cultivation
This is the species where the pillar's cold-hardiness notes come into play:
- Cold tolerance. Exceptional. Survives brief exposures to −25 °C when dry, and routine winters at −15 °C without damage. The load-bearing variable is dryness; a plant that would tolerate −20 °C dry will rot at −5 °C in saturated soil.
- Light. Full sun in any climate. Does not tolerate shade in cultivation.
- Water. Less than for any other commonly grown agave. Outdoor specimens in free-draining ground often need no supplemental water at all after the first year. Under glass, water once every 2 to 3 weeks in active growth and essentially not at all in winter.
- Substrate. The pillar recipe works, but increase mineral content to 75% or more for outdoor plantings in rainy climates. Raised gravel beds or rock-garden pockets are ideal.
The single most common failure mode for this species in cultivation is winter rot from wet soil, not cold damage. Site selection on a slope or raised bed with no winter irrigation is more important than any frost protection.
Propagation
Offsets are the standard route but are produced slowly. A mature rosette may yield only 2 to 5 pups in a decade. Sever offsets once they have formed their own root plate, callus for a week, and pot up in mineral substrate.
Seed propagates readily from fresh material, but the 20-to-30-year wait for flowering makes this impractical outside conservation or botanical-garden settings.
Notes
The name "mescal agave" in older US horticultural literature refers to A. parryi, not to the Mexican mescal-production species, which are principally A. angustifolia and A. salmiana. Apache peoples roasted the hearts of A. parryi for food, and the common name reflects that use rather than a distilling tradition.
If you live anywhere in USDA zones 5 through 9 and want a permanent outdoor agave, this is the default choice. It is also the species least likely to be damaged by novice cultivation errors, provided the drainage question is answered correctly from the start.
See also: Agave americana, Agave victoriae-reginae, Agave palmeri.