DESCRIPTION:This group consists of about 40 perennials and evergreen shrubs and trees native to semi-arid regions of North America, Central America, and Mexico. These plants range in height from 28 inches to 40 feet depending upon the variety. Yuccas make great houseplants when young. Yuccas produce rosettes of rigid, slender, sword-shaped leaves and tall, candelabrum-like panicles of large, drooping, waxy, bell-shaped flowers. Y. filamentosa (Adam's Needle) is a hardy kind that forms clumps of spreading or upright, slightly bloomy leaves. Twisting white threads form along the edges of the leaves. This plant is a source of fiber used for making rope. From mid- to late summer, tall panicles (3 to 61/2 feet high) arise that are covered with milk white flowers, each 2 to 3 inches long. Flowers are produced even on young plants. Y. filamentosa var. Variegata is a small variety whose dark green leaves are edged with a wide band of cream. Y. glauca (Spanish bayonet; Soapweed) is a low-growing, hardy plant with a round head of thin, grayish-green leaves that are edged with white and curly threads. In mid- to late summer, tall racemes, 3 to 5 feet high, of greenish-white flowers, 2 to 3 inches long, are produced. This variety doesn't flower until mature. Y. gloriosa (Spanish Dagger; Mound-Lily Yucca) forms a fairly hardy shrub that reaches 8 feet high. It has thick stem and few or no branches. At the limits of its range, it may not form a stem. The green, sharp-tipped leaves are covered with bloom and grow up to 2 feet long and 3 to 4 inches wide. They are produced in a compact, terminal head. From mid-summer to early autumn, panicles reaching a height from 3 to 61/2 feet, are produced. They are densely covered with large (up to 4 inches), white or greenish white flowers, sometimes stained with red on the outside. Y. whipplei (Our ****'s Candle) is a tender species that forms a thick, round clump of long, slender, toothed, blue leaves that are covered with bloom. In late spring and early summer, very tall panicles reaching 6 to 11 feet in height arise from the leaves. They are crowded with large, pleasantly scented, greenish white to white flowers that are edged with purple. This plant can withstand frost, but should only be grown in very mild climates in well-drained soil. Y. brevifolia (Joshua tree) is an interesting, tender variety that grows up to 30 feet high. It has a gnarled appearance with clumps of leaves terminating the branches. It bears large panicles of greenish-white flowers.
POTTING: There are several hardy species of Yucca that can be grown outdoors in all but extremely cold climates. Yuccas should be grown in a hot, dry site in well-drained soil in full sun. They are great for growing in gardens in coastal areas. If the dead leaves do not fall off, they should be cut off once or twice a year.
PROPAGATION: These plants are usually increased by offsets or cuttings. Short shoots can usually be taken off of the old stems in the spring and summer. Pot these shoots individually in containers or in a propagating bed in a warm, closed frame where they will form roots quickly. Shoots can also be detached from the base of old plants. Pieces of old stems can be laid on sand or some other medium in a warm greenhouse; shoots that can be used as cuttings will grow from dormant buds. A head of leaves from a branch that has broken off a large plant can be rooted in a container filled with sandy soil. Cut the head from the branch just a few inches below the lower leaves and remove a few of the lower leaves before inserting in the pot of soil. Loosely tie the leaves together in an upright position and place the plant in a warm greenhouse, where roots should form in a few weeks.
SPECIES & VARIETIES: Y. filamentosa & var. Bright Edge & Variegata; Y. flaccida & var. Golden Sword & Ivory; Y. glauca; Y. gloriosa & var. Variegata; Y. recurvifolia; Y. whipplei; Y. aloifolia; Y. brevifolia; Y. elephantipes; Y.rigida; Y. endlichiana; Y. elata; Y. carnerosana; Y. harrimaniae; Y. baccata.