Thursday, July 22, 2010

Agave, Yucca, and Related Plants

Agave and Yucca for Austin

First, let’s make sure we are clear about the differences between these plants, cacti, and succulents. Plants in the family agavaceae form from a central rosette with rigid stems and piercing tips on the ends of the stems. Cacti, on the other hand, are spinney and leafless plants that share the same arid conditions. Succulents comprise a large variety of species and may or may not be freeze hardy. They still prefer an arid dry environment. All these plants are succulents.

We will list several species here that have proven to do well in Austin and the surrounding regions. All require good drainage. Adding an aggregate material, such as expanded shale or decomposed granite works well. If you have very heavy clay, a bit of compost will help as well. Full to part sun for most, but there are exceptions. While most would survive if never watered, plants will look best if given a deep soaking occasionally in very hot, dry summers.

Agaves: Possibly one of the most striking families of plants, agaves are a large group with great variety in color and size. Nearly all are stemless (the rosette stays low to the ground, unlike some yucca or others). Also, most are monocarpic, meaning they flower once in their life, then die. The bloom is spectacular and they often leave a way to propagate many more. One downside to the agave, they cannot be pruned for size restriction like most shrubs. While older leaves can be removed, generally they should be allowed to grow and can become quite large. Be sure to check size info to pick a plant that won’t outgrow your spot. Many species are also available in variegated forms, some of which may be more cold sensitive.

A. Americana – Possibly the most common here in Austin. Pups freely. 6’x8’. Z8-11

A. parryi-Parry Agave. 2’x2’ Z5-11. Ssp.’Truncata’-Artichoke Agave. Also 2’x2’, Z8-11. More compact growth than regular parryi.

A. Montana- 4’x5’. Z6-11

A. Victoria Regina-One of the smallest. 1.5’x1.5’ Z8-11.

A. Salmiana-One of the largest. Green leaves. 8’x10’ Z8-11

A. Franzosini-Another very large one. Silver leaves. 8’x10’ Z8-11

A.Geminiflora– Twin Flowered Agave. May prefer some afternoon shade. May bllom without dying. 3’x3’. Z8-11

A.Vilmoriana- Octopus Agave. 4’x4’ Z9-11,

Other small agave that work well here: A. Lopantha, A. Bracteosa, A. Filifera, A. Stricta

Yuccas: A relative of the agave, yuccas are notable for their rosettes of evergreen, tough, sword-shaped leaves and large terminal clusters of white or whitish flowers. They are native to the hot and dry (arid) parts of North America, Central America, South America, and the West Indies. Unlike most agave, once mature, yuccas will bloom every year. Larger specimens may produce numerous bloom spikes. Sizes listed are maturity and may take several years to be achieved. Like most agave, most yuccas prefer full to part sun and good drainage.

Y. aloifolia- Spanish Dagger. 10’ tall on trunk. Z7-11.

Y. baccata- Banana Yucca. 4’ tall, forms colony. Z5-11.

Y. filamentosa- Adam’s Needle. 4’ tall, form colony. Z4-11

Y. pallida- Pale Leaf Yucca. 3’ tall, forms colony. Z7-11

Y. pendula (recurvifolia)- Soft Leaf Yucca. 8’ tall, form small colony. Z7-11. Tolerates medium shade.

Y. rostrata- Beaked Yucca. 15’+, usually solitary. Z5-11

Y. rupicola- Twisted Leaf Yucca. 2’ tall, forms small colony. Z8-11. Tolerates shade well and may burn in too much sun.

Y. thompsoniana- Thompson’s Yucca. 10’ tall, usually solitary. Z7-11

Hesperaloe: These yucca-like plants are also in the agave family. The plants have long, narrow leaves produced in a basal rosette and flowers borne on long panicles or racemes. The species are native to arid parts of Texas and Mexico. Sizes vary, depending on species. Flowers range from red to yellow, pink to white. Some species include: H. parvifola- Red Yucca.(also comes in yellow, and sold as Yellow Yucca), A fairly common plant in Austin and possibly one of the easiest plants to grow. H. funifera- Giant Red Yucca, and H. nocturna- Night Blooming Yucca.

Nolina and Dasylirion: Other agave relatives of note. These families included the sotols and tree grasses. Like yuccas, they bloom annually, once mature. Many of these plants have finer textures and some are spineless, making for a friendlier arid garden.