Pacific Plant Promotions: Agave ‘Blue Flame’

By: Bart O’Brien

Bart O’Brien is one of Southern California’s most highly respected native plant specialists and co-author with David Fross and Carol…

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Agave ‘Blue Flame’ at Rancho Santa Ana Botanic Garden. Author’s photographs

Agave ‘Blue Flame’ at Rancho Santa Ana Botanic Garden. Author’s photographs

Pacific Plant Promotions (PPP), in partnership with International Succulent Introductions (ISI), is pleased to offer a particularly fine landscape plant: Agave ‘Blue Flame’. The lush blue gray rosettes of this agave are attractive in many garden situations: cascading over low walls, in decorative pots, amongst large boulders, in parkways and street medians, and juxtaposed against the strong lines of contemporary architecture. The only thing to keep in mind is that the plant will grow considerably larger and faster than might be expected. This is the first joint offering of PPP and ISI, and it is the first succulent offered to readers of Pacific Horticulture through PPP.

This spectacular hybrid between Agave shawii and A. attenuata was created by noted Southern California plantsman and hybridizer David Verity in the early 1960s at the Mildred E Mathias Botanical Garden (MEMBG) on the campus of University of California, Los Angeles, (UCLA). The hybrid is all the more notable as its parents are placed in two distinct sections of the genus; A. shawii (the seed parent) is in section Agave, whereas A. attenuata (the pollen parent) is in section Littaea. The reciprocal cross was not attempted. Several different individuals resulted from Verity’s cross and were subsequently planted out near one another on a relatively steep northeast-facing clay slope at MEMBG. Though the actual number of individuals is uncertain, there are at least two surviving clones of this hybrid. All of the plants of Agave ‘Blue Flame’ offered by PPP have been produced by tissue culture at Rancho Soledad Nurseries from a single individual at the Huntington Botanical Gardens (HBG) in San Marino.

Agave ‘Blue Flame’ produces large rosettes, up to five feet tall and six feet wide, of smooth blue gray leaves. Individual leaves may reach thirty inches in length and six inches wide. The blue gray color is most intense on fresh new growth, and becomes increasingly green with age. The leaf margin is edged with inconsequential teeth about one-sixteenth inch long; each leaf terminates in an inch-long, inward-curving, sharp spine. Leaf margins (and all spines) are red brown in color. Immediately adjacent to this red brown zone is a thin band of living leaf tissue that is yellow green. When backlit by the sun, the leaf margins glow. The largest specimen of ‘Blue Flame’ at Rancho Santa Ana Botanic Garden (RSABG) in Claremont has formed a mass of rosettes that is nine feet long, six feet wide, and five feet tall; it was planted in October, 1998, from a two-gallon container.

Silhouetted against a shadowy palm are the main and subsidiary inflorescences of Agave ‘Blue Flame’

Silhouetted against a shadowy palm are the main and subsidiary inflorescences of Agave ‘Blue Flame’

Vigorous plants grown in rich soils will produce astounding curved to arching inflorescences up to twenty feet or more in length, often surrounded by several (considerably smaller) subsidiary inflorescences. When grown in lean, dry soils the inflorescence may be straight, solitary, and only eight to ten feet tall. Individual yellow flowers are held in dozens of relatively small clusters along the central stalk. As in all agaves, the flowers open from the base of the inflorescence to the tip over a period of several weeks. Each rosette will die after flowering and will need to be removed; pups are so freely produced that the clump will continue to expand. The first recorded flowering of this clone was a sixteen-year-old plant at HBG in 1983. Surprisingly, ‘Blue Flame’ will produce at least some viable seed. These infrequent, fertile seeds are thin black wafers, typical of the genus, whereas the plentiful infertile seeds are pale brown.

Agave shawii is native from southernmost California through the northern half of Mexico’s Baja California peninsula—encompassing both desert and coastal mediterranean-climate environments. Agave attenuata is native to central Mexico, where it receives summer rainfall. Agave ‘Blue Flame’ is surprisingly adaptable and tolerates watering at any time of the year in Southern California, though it tends to favor its A. shawii parent by flowering during fall and winter, and actively producing new roots most freely in autumn. Established plants, especially those near the coast, are completely drought tolerant, although most plants perform best with some summer irrigation. To date, no plants are known to have died because of summer watering. Planting from containers may be done at any time of the year.

In most of Southern California, this plant is best grown in full sun and well-drained soil. In extremely hot or desert areas, ‘Blue Flame’ should not be grown in full sun, but rather in light shade, such as that provided by palo verde trees (Parkinsonia); at the minimum, plants should be protected from direct afternoon sunshine. If unattractive sunburned foliage is an ongoing problem, transplant your specimen to another location early in fall. It will reestablish quickly, and the damaged leaves will soon be hidden under new growth.

The hardiness of ‘Blue Flame’ has not been tested outside of Phoenix, Arizona, and the greater Los Angeles basin. Temperatures in the mid-20s F may damage the foliage, but recovery is usually quick. Recently planted young specimens in a cold air pocket at RSABG had noticeable leaf damage from the coldest winter night of 2003-2004, although they recovered rapidly during the following spring; none of the established plantings were affected. An educated guess would suggest that established plants should recover from temperatures in the low 20s F.

Propagation can be readily accomplished by removing pups (just push them off) from along the main stem in early fall. Let these “cuttings” sit and dry for a few days in a cool, shaded, dry location. No rooting hormones are needed. Plant them in containers of a mix of one-half potting soil and one-half perlite, and water sparingly until active new growth appears. Young plants develop quickly.

Although this agave has not been available commercially until now, it has been known informally for years by a number of different names, none of them legitimately published: Agave ‘David Verity’, A. ‘Huntington Tooth’,  A. x verityi, A. attenuata x A. shawii, and A. shawii x A. attenuata. It has also been known by its MEMBG accession number (65.475), its HBG accession number (19706), its RSABG accession number (18763), and its ISI number (2005-6).

Clustered yellow flowers of Agave ‘Blue Flame’

Clustered yellow flowers of Agave ‘Blue Flame’

The creator of Agave ‘Blue Flame’, David Verity, has been a fixture of the Southern California horticultural and botanical community for decades. He is widely known for his many horticultural contributions and his skills in hybridization. In the latter category, Pacific Horticulture readers may be aware of his notable hybrids of both Aloe and Mimulus (Diplacus), including Aloe ‘David Verity’ (introduced by ISI in 2001) and Mimulus ‘Verity White’ and ‘Valentine’ (distributed by PPP in 2003). He is currently working on creating dwarf, reblooming hybrids of orchid cactus (Epiphyllum) and intergeneric hybrids between two shrubs in the potato family, Iochroma and Acnistus.

As part of the Pacific Plant Promotions program, through which new and unusual plants are made available to readers of Pacific Horticulture, Rancho Santa Ana Botanic Garden is offering plants of Agave ‘Blue Flame’ for shipment in August and September, 2005. To order one, see the Pacific Plant Promotions reservation card (opposite page 64) for details.