Botanical Name: Yucca Carnerosana
Plant Common Name: Carneros Yucca, Giant SpanishDagger, Giant Yucca, Palma
Origin and Habitat: Yucca Carnerosana, the Giant Spanish Dagger, is a large broad-leaved tree yucca, native to Northern Mexico with its range extending from Chihuahua and Coahuila into the Trans-Pecos area of South Western Texas. There is also a separate population in Nuevo Leon, San Luis Potosi, Durango and Zacatecas. It reaches as far north as Brewster County in Texas encompassing the Big Bend National Park where it grows at elevations of 6700 feet and this area - one the most mountainous and arid parts of the Chihuahuan Desert - is a good indication of its cultivational requirements and general toughness.
General Description: In the landscape, Yucca are grown as specimen plants to draw visual focus to specific garden areas. They offer fine-textured foliage along with bold, architectural forms. Plant them along a patio or outdoor room where their night blooms are best enjoyed.
Older plants may reach a height of 15 feet or more. Rarely, a plant might divide at the head so that there is more than one crown of leaves, but this is unusual.
Trunk: Although it is often a single trunk plant, sometimes Yucca Carnerosana will put out a few offshoots at the base, and when these grow up there will be a cluster of several trunks with the original one the tallest. The trunks of this species are quite robust, usually more than a foot in diameter, and they are densely covered with dried old leaves. On a tall specimen the oldest leaves may eventually loosen and fall away to reveal the gray-brown trunk.
Exposure: They thrive best in full sun, but can be grown with some shade and humidity, but may become leggy. Place your yucca in full sunlight.
They are not picky about sun or shade but do need bright light if indoors. Not enough light can sometimes discourage blooms on yucca plants and can be one reason for yellowing leaves.
Hardiness: Best where winter temperatures stay above 0° C, but is hardy to around -12° C. Plants in containers can be moved inside during longer cold spells.
Hardiness Zone: 5
Soil/Substrat: Plant in very fast draining soil. It is adapted to a hot, dry environment, but has some tolerance to moisture and humidity when planted in a very well-draining soil as the roots of Yuccas rot easily in wet soil. It is noted as preferring alkaline conditions. It can survive in dry and poor soils pH 5.5 to 7.5. Although it appreciates some moisture in summer, damp winters are not to its liking.
Waterings: Treat like a succulent. Yuccas are drought resistant and can survive for many months without water. However, they grow faster if watered well (don't water the crown, though they rot easily). In the garden they should be placed in a sunny, well-drained area with additional summer water in dry climates. Watering from a hose or sprinkler should be done slowly and deeply, not frequently, to avoid shallow root development or root diseases. Allow soil to dry several inches deep before irrigating.
Provide little or no water in winter. Most winter injury is from drying out, not cold temperatures. Be prepared to water during prolonged sunny, windy, dry spells even in the winter. Mulches help prevent water loss during hot, windy, or sunny weather.
Fertilization: Proper fertilization of yucca plants starts with application. Fertilizer should be evenly spread in a circle over the soil of the surface where the roots of the plants spread. Apply water immediately after applying fertilizer to the soil to help the fertilizer seep into the ground. Fertilizer should be applied to yucca plants once a year, at most, in the early summer.
Sometimes, however, applying fertilizer to yucca plants may do more harm than good. The salt found in fertilizers may harm plants that are already suffering from unhealthy roots. Giving plants too many nutrients may be as detrimental as giving them too few. Don't start fertilizing yucca plants, or giving them extra fertilizer, simply because they look unhealthy. Follow a fertilizing schedule and stick to it to avoid doing damage to the plant with excess fertilization treatments. Never fertilize yucca plants when they are newly transplanted.
Maintenance: Outdoor yucca plant care: Plants prefer dry soil that has full access to the sun. Avoid overwatering the plant as this can cause rotting of the roots. Cut off all the dead leaves in order to keep the plant neat. Yuccas are not fond of being transplanted, so make sure that you will choose the right location before planting them.
For potted houseplant, Yucca plant care indoors: make sure that the plant has sufficient access to intense light. Use heavy pots as yuccas tend to be heavy in both their stem and foliage. When watering, simply sprinkle water on the top of the plant if the soil feels dry. Although yuccas do not prefer to watered heavily, draught or lack of water can cause the leaves to turn brown or yellow. Remove dead and yellow leaves from the yucca plant, and dispose of the leaves in the garbage. Keep healthy yucca leaves clean by dusting them occasionally with a soft cloth. Dust will block sunlight and air from entering the leaves.
Blooming season/Fruit: Yucca Carnerosana produces panicles of white campanulate flowers from March to April. The dense cluster of flowers shoots up with breathtaking speed so that one might see the beginnings of an emerging stalk one week and then come back to find it already in flower the next. There are hundreds of snow-white flowers in a cluster, so a plant in bloom is a memorable sight, reminiscent of an eruption of Old Faithful, in slow motion.
Perhaps because the flower display is so extravagant, plants do not flower every year.
Problems: There can occur rust fungus, specially after a wet warm winter, If the damage is done there are noting to do, but the rust fungus rarely spread to the new growth. The rust fungus can be prevented if the plants are protected against winter moisture or with a sheet of glass.
Watch your yucca plant or signs of anthracnose of agaves, a fungal disease that causes lesions on leaves and red to orange spore masses. Remove affected leaves at first sign of infection.
Check your yucca plant often for signs of spotted mites, which leave tell-tale gray webs under leaves, as well as tan or gray speckling on the plant. Spray the yucca plant with insecticidal soap to control the mites; you can also discourage them by misting your yucca plant frequently.
Water regularly, because if the plant doesn’t get enough liquid, its leaves will soon turn yellow and then brown.
Special notes: Yuccas have long been used by Native Americans for soap making, food, and fiber. The roots of some species are high in saponins, which can be mixed with fats to make basic soap. The stems, flowers, and seeds of most, but not all, Yucca are edible and may be eaten cooked or raw. And the soft, strong, pliable Yucca leaf fibers are useful for making everything from ropes to woven blankets and sandals.