Coming into their full glory in spring when stalks of bell-shaped, fragrant flowers appear from leaf rosettes, yuccas (Yucca spp.) are tough plants that thrive in hot, dry places. They're hardy in U.S. Department of Agriculture plant hardiness zones 4 through 11, depending on the variety. The sword-shaped leaves can have sharp, pointed ends. Native to North America, Mexico and the Caribbean, there are about 30 species. Yuccas either grow as stemless basal rosettes or the stems form trunks of varying heights, some of them branching and tree-like. They require minimal care to thrive.
Inhabitants of arid areas with hot summers, yuccas are drought tolerant. During their first year in the garden, water them deeply if the top 2 inches of soil becomes dry during the spring, summer and fall. After establishment, plants need little extra water. Yuccas don't do well in conditions where the soil stays moist. Prevent possible root rot by providing good drainage. Water drains away from roots if yuccas are on a slope or mound. Container-grown yuccas offer the advantage of a small soil mass around the roots that dries out more quickly than if yuccas are in the ground, giving them better drainage; use containers with drainage holes and a succulent potting mix. Yuccas in containers can be moved during extended rainy periods to allow the soil to dry.
Light and Fertilizing
Yuccas do best in full sun. They'll tolerate partial shade if they receive at least six hours of direct sunlight. Truly low-maintenance plants, yuccas don't usually need supplemental fertilizing once they're established. For young plants, low rates of fertilizer are optional to improve early growth rates. Apply a water-soluble 20-20-20 fertilizer at half strength in the spring during the first two years the plant is in the ground. Mix 1 1/2 teaspoons per 1 gallon of water and give enough of the solution to soak through the root zone area.
Most yuccas don't need pruning if you've spaced them correctly. Before you put the plant in place, look up the mature size of the species so you don't have to try to chop leaves or branches back if they intrude into pathways. For yuccas that eventually develop trunks, you may wish to trim away some of the dead lower leaves, but there is no need to do so for the health of the plant. Clean pruning tools with a cloth soaked in rubbing alcohol to prevent disease spread. Sprawling species such as Spanish bayonet (Yucca aloifolia, USDA zones 8 through 11) may need pruning if given limited space. Due to the sharp points on the leaves and the thick growth, pruning branches from Spanish bayonet is difficult and potentially dangerous. Site them where they have lots of room and pruning isn't needed.
Depending on the species, some yuccas benefit from frost protection, especially when young. Some examples are Spanish bayonet, giant yucca (Yucca guatemalensis, USDA zones 9 through 11) and Torrey's yucca (Yucca torreyi, USDA zones 8a through 11b). Cover the plants with a frost blanket when cold is predicted, or keep young yuccas as container plants that can be moved indoors before frost arrives. Some of these species are so large when mature that covering them isn't possible.
Pests and Diseases
Yuccas growing in the landscape seldom have pests or diseases. Two-spotted mites (Tetranychus urticae) may occur on some species of yucca, such as Spanish bayonet and mound lily yucca (Yucca gloriosa, USDA zones 6 through 11). Remove the mites and their webbing using strong streams of water. Keep the humidity around the plants high with occasional misting or washing of foliage, as humidity reduces mite populations.
- Fine Gardening: Designing With Spiky Plants
- U.S. Department of Agriculture Natural Resources Conservation Atlas: Classification for Kingdom Plantae Down to Genus Yucca L.
- University of Florida IFAS Extension: Agave and Yucca: Tough Plants for Tough Times
- Floridata: Yucca Aloifolia
- Arizona State University: Yucca Guatemalensis
- Southern Nevada Water Authority: Torrey's Yucca
- University of Arizona Cooperative Extension: Cactus, Agave, Yucca and Ocotillo
- University of Arizona Cooperative Extension: Problems and Pests of Agave, Aloe, Cactus and Yucca
- University of Florida IFAS Extension: Yucca Gloriosa Spanish Dagger, Mound Lily Yucca
- South Australian Reseearch and Development: Horticulture: Two Spotted Mite
Carolyn Csanyi began writing in 1973, specializing in topics related to plants, insects and southwestern ecology. Her work has appeared in the "American Midland Naturalist" and Greenwood Press. Csanyi holds a Doctor of Philosophy in biology from the University of Wisconsin at Madison.