Plant of the Month: Swan’s neck agave adds beauty and grows in variety of places

  • The inflorescence of the swan’s neck agave consists of flower buds as well as open greenish-yellow flowers followed by small round green fruit. (Photo courtesy /Wikipedia)
  • Like other agaves, the swan’s neck develops a supportive trunk as it matures. (Phot courtesy / legsgogardening.com)
  • The leaves of the swan’s neck agave are soft and unarmed. (Photo courtesy / worldofsucculents.com)
  • When planted in a group the swan’s neck agave’s necks will often arch in the same direction. (Photo courtesy / Kim and Forest Starr)

The lovely arching inflorescence of the Agave attenuata can be spotted in many gardens in Kona this month. This attractive plant is native to Mexico and is now the most commonly grown agave in Hawaii. Beyond the beauty of its blooming raceme, the swan’s neck agave has many features to recommend it to Kona growers.

Hailing from upper elevations in the western states of Mexico, attenuate adapts easily to our climate and can grow in many of the locations and soil types that we have here. It has soft light green leaves that make it an attractive addition to any landscape and its drought tolerance recommends it for local xeriscape gardens.

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Agave attenuate is commonly known as either swan’s neck agave or fox tail agave. Both common names refer to the long flower stalk it produces annually. The stalk can be 10 or more feet long growing straight up then arching so the tip turns downward. The graceful arch does resemble the neck of a swan and its fluffy appearance is similar to a fox’s tail.

This member of the large Agavaceae family is one of the few in the Agave genera that is un-armed. It has neither sharp leaf tips nor spiny leaf margins like some of its close relatives. The century plant (Agave americana) and other less common species that grow here all have spiny leaf margins or sharp pointed tips. Among the more than 600 species in the Agavaceae family are many un-armed plants that are commonly grown in Hawaii. Ti plants, members of the Cordyline genera, as well as dracenas, sensevierias and yuccas are all in the Agavaceae family.

Agave attenuata is a succulent perennial. The supporting trunk can grow to 5 feet tall and the plant can spread out to 8 or more feet wide with individual rosettes as large as 4 feet across. The pale green leaves have pointed tips but are soft and pliable.

The swan’s neck agave is unique in its flowering habit. This agave usually blooms once a year, but unlike other agaves, it does not die after flowering. It produces a long and dense raceme of tiny light greenish yellow flowers, usually in the fall. As the stalk grows the weight of the long tip causes it to turn downward producing a graceful arch much like the neck of a swan. The flowers are pollinated on the maturing stalk but soon drop off leaving small green fruit in their place. This fruit will eventually drop as well. In the right conditions, the seeds will germinate and produce a new plant.

A much more reliable propagation method for this species is to replant off-shoots, known as pups that are produced on the trunk below the leaves. Like many agave plants, attenuata does not have deep roots but the pups should root easily when they fall or are placed on a fertile growing medium. When they are young, occasional watering will encourage them to grow and become established. This agave grows best when it is planted out of direct, hot sun, in partial shade or a spot that doesn’t get day-long sun and heat exposure. Though they prefer occasional watering, they can also sustain short periods of drought. Soil that drains well is the best growing medium for this and other succulents that cannot tolerate wet feet.

Another attractive feature of the swan’s neck agave is its low maintenance requirements. Very few pests or diseases attack this plant. It can survive on very little fertilizer though a light application several times a year can help it to thrive. The only pruning needed is to cut back the inflorescence once it has died and to remove any suckers from the trunk that you want to use for propagating new plants.

The swan’s neck agave can add interest to your landscape in several ways. When planted in a group, the necks will often all face in the same direction which can provide a striking display. Grown singly in a small garden or a pot, they make an eye-catching specimen plant when in bloom. Though they have shallow roots and are well suited to growing in a pot, a large, heavy pot is recommended to prevent toppling when the heavy blossom stalk appears.

Since many swan’s neck agave are currently in bloom and easy to spot around town, you may want to ask someone who has them to share a few pups with you. Otherwise you can check with Margo from Sunrise at 640-9191 to see if she can recommend a source.

Diana Duff is a plant adviser, educator and consultant living in a dryland forest north of Kailua-Kona.

Gardening Events

Saturday: “Work Day at Amy Greenwell Garden” from 9 a.m. to 12:30 p.m. Meet at the Garden Visitor Center across from the Manago Hotel in Captain Cook. Volunteers will be able to help with garden maintenance and are invited to bring a brown bag lunch. Water and snacks provided. Call Peter at 323-3318 for more information.

Farmer Direct Markets

Wednesday: “Hooulu Farmers Market” 9 a.m. to 2 p.m. at Sheraton Kona Resort &Spa at Keauhou Bay

Saturday: “Keauhou Farmers Market” 8 a.m. to noon at Keauhou Shopping Center

“Kamuela Farmer’s Market” from 7 a.m. to noon at Pukalani Stables

“Waimea Town Market” from 7:30 a.m. to noon at the Parker School in central Waimea

“Waimea Homestead Farmers Market” from 7 a.m. to noon at the Waimea Middle and Elementary School Playground

Sunday: “Pure Kona Green Market” 9 a.m. to 2 p.m. at Amy Greenwell Garden in Captain Cook

“Hamakua Harvest” 9 a.m. to 2 p.m. at Highway 19 and Mamane Street in Honokaa

Plant Advice Lines

Anytime: konamg@ctahr.hawaii.edu

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Tuesdays and Thursdays: 9 a.m. to noon at UH-CES in Kainaliu – 322-4893

Mondays and Fridays: 9 a.m. to noon at UH CES at Komohana in Hilo 981-5199 or himga@hawaii.edu