Most of us in Colorado know that Agave is the source of tequilla and Agave sweetener, but fewer have seen it growing here. Even more rare is the sight of Agave in bloom. The Century Plant doesn’t really take 100 years to bloom, but it does seem to take forever. After 13 years, my Agave parryi, whose bold and armed rosette finally achieved 31” in diameter and 16” tall, began this May to push up a bloom stalk. Then it skyrocketed 3”-4” A DAY until it reached eleven and half feet tall with a candelabra  of rich yellow flowers. Eclectic horticulturist Bob Nold says in his book High and Dry, “Their flowering, mostly, is as spectacular a thing as the plant kingdom has invented….”
This spectacle not only attracted visitors like a zoo, but it magnetized an oriole to sup at its cups of nectar, as well as hundreds of bees and wasps. Hummingbirds are supposed to be attracted, though we didn’t see any, as are moths, flies and in some areas, bats. Even after the freshness of the flowers has faded, it is still worth a visit to see.
I asked Panayoti Kelaidis, director of outreach at Denver Botanic Gardens and master horticulturist, if Agave is well-adapted to Colorado conditions. He answered that some varieties do well in the Denver-Metro-Boulder area,including Agave parryi, A.neomexicana and A. havardiana. Other species are possible if established in favorable conditions and in a good year, including Agave lechiguilla, A. polyanthaflora, A. utahensis and A. deserti. Panayoti mentioned that favorable conditions include a rich, gravelly soil with some compost and a gravel mulch in full sun, especially on the south side of a rock. Wet and windy sites should be avoided. Mr. Kelaidis added that there are 6 Agaves in bloom at DBG this year, of three species. Plants grown from seed collected in cold-winter areas are most likely to succeed here.
One might assume that Agaves need no supplemental water, like cacti, but that is not correct. Nold says, in nature, Agaves often get summer monsoon rain in the late summer, and suggests a little summer irrigation. He also mentions that dry clay is OK, but a mulch of leaves or other organic matter is often fatal.
Jim Knopf, Boulder xeriscape mentor and landscape architect, said he has grown several varieties, but none of them has bloomed yet. He believes a hot location is good and that winter snow cover that melts off is beneficial. His research found corroboration for my theory that last winter’s sudden below zero cold snap damaged some plants and may have shocked mine (and others) into blooming in order to procreate.  Mr. Knopf mentioned that he has been growing Agave lechiguilla (commonly called Shin Dagger) for ten years, and has been trying for two years to dig it out. Agaves propagate not only from seed but from “pups” that pop up dangerously from the root with their sharp spine leading the way. For the Agave, this is an important point, because after the long wait, and spectacular bloom, the main rosette will die.
Even without the gorgeous flowers, the evergreen rosette of the Agave makes a wonderful architectural feature in a Colorado garden, especially in winter. And it is fascinating to behold the imprints of the neighboring pads, as the rosette unfolds from the center. This plant is not recommended to grow around young children, but it is a delight and a wonder in the xeriscape garden.
Further information about Agaves can be found in Robert Nold’s book High and Dry. Plants of hardy varieties can be found at Timberline Gardens, Harlequin’s Gardens and Paulino’s.