Agave havardiana - Cactus Club

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Agave havardiana

Plant of the Month > 2018

      Agave havardiana is an attractive, medium sized Agave with glaucus grey to bluish foliage. It produces compact rosettes to about 2 feet tall and spreading to about 3 feet (one source suggesting 5 feet) across. Foliage is about 24 inches long, and is about 6 inches wide, with the leaves flaring in the middle, and tapering to a sharp terminal spine, with marginal teeth spaced 1 to 2 inches apart. This species is native to the northern Chihuahuan Desert, in western Texas, south eastern New Mexico and into the adjacent Mexican states of Coahuila, and Chihuahua. Plants typically grow at elevations of 4000 to 6500 feet. It is closely related to Agave neomexicana and A. parryi.

      At maturity, (probably at 15 to 20 years or more) this plant will produce a flowering spike 6 to 13 feet tall and bearing 12 to 20 branches which are tightly packed with 3 inch yellow flowers. As with all Agaves, each plant of this species will flower only once in its lifetime, dying completely following flowering and seed production. Some plants may produce a few offsets after flowering.

      This species is one of a small handful of Agaves which has the reputation of being exceptionally cold hardy, surviving temperatures to -20 degrees in the Denver Botanic Gardens. Agave havardiana has been a popular landscaping plant in New Mexico, and Texas for many years; but with growing interest in gardening with hardy cacti and other succulents, this plant has been widely introduced through the states of the high plains, the mountain west, drier regions of the Western coastline, much of the Gulf region, and along the Atlantic coast to at least as far north as North Carolina. I believe that John Spain reported success in growing this plant in his garden in Connecticut. Many growers continue to test its hardiness in more northern settings: some catalogs list its hardiness as a zone 5, but some of the more conservative estimates place it in a zone 7

       I first began growing Agave havardiana some years ago when I was testing cactus and other succulents for their hardiness and suitability for Ohio gardens – this species had a reputation for extreme cold hardiness, and in regions of the high plains and mountain west, it has proven to be reliably hardy to -10 and even -20 degrees, but in Ohio, with its extended wet winter conditions, my tests indicated that this plant could barely survive temperatures to perhaps 15 to 10 degrees. After a few trials, I stopped growing this plant.

      I believe that it was 3 years ago that I had another opportunity to try this species, when rooted offsets were offered at a joint meeting with the Midwest Cactus and Succulent Society. The plant offered had already been subjected to temperatures of 17 degrees, which it survived without damage. This time, I decided to grow it as a potted plant on the patio from spring through fall, bringing it indoors only when temperatures fell below freezing. While my plant is still an adolescent, not yet producing the dense and tight rosette of leaves typical of more mature plants in habitat, it has grown considerably, and has produced 4 offsets. Plants in habitat seldom produce offsets, and then only very sparingly, so this trait in my plant is unusual. More than likely, this cultivar was selected specifically for this trait – which would make it easier to propagate it in good numbers. Agave havardiana has a reputation of being slow to establish, and while its rate of growth is considerably faster than that of Agave victoria reginae, under ideal conditions, it probably would take a minimum of 5 to 7 years to grow from seedling to maturity; and under less than ideal conditions, this could take much longer.

Smaller plants make very attractive plants for the home - but remember that these are not for every household - even at smaller sizes, the rigid terminal spines on these plants can be formidable, and will can cause significant injury, so make every effort to keep it away from high traffic areas. Ultimately, my plant will grow to a size where I can no longer bring it indoors; at this time, I will attempt to overwinter it on my front porch, which is sheltered from rainfall, and high winds - given this protection, I hope that it will be able to tolerate colder temperatures, enabling me to maintain this plant for many additional years.

      Agave havardiana will eventually grow too large even for even the most devoted growers of succulents to maintain indoors; it is best reserved for the landscape - both as a potted plant plant for sunny patios, and in the landscape. My notes for growing hardy cacti may be a good starting point for growing this plant outdoors, but my experience indicates that this plant should be provided with exceptional drainage - as it seems to be exceptionally prone to root loss, and eventual death when subjected to cold and wet conditions during the coldest weather of fall, winter and spring. While my experiments with seedling plants were disappointing, suggesting that this plant is not hardy here, John Spain related to me that he had much better success in growing the cold hardy agaves when he planted larger, more mature plant in his garden, so perhaps my judgement was a bit premature - I will continue to make trials with this plant, and hope to make updates in future years.

    Always remember that most agaves produce awl like spines held rigidly on the leaf tips - making them dangerously unsuitable for most households and gardens; place them far away from high traffic areas: always treat them with respect!

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