Ask Mr. Smarty Plants

Forgive us for being a little impertinent, but why would you want to? Please read our Native Plant Database webpage on Yucca brevifolia (Joshua tree) and note, particularly, the sections on Distribution and Growing Conditions:

Growing Conditions

Light Requirement: Sun
Soil Description: Sandy or rocky soils."

You are correct that drainage would be one problem in maintaining the plant, but sheltering the top of the plant from rainfall would be futile. The rain falls on plants but is not used by the plants until the water has gone into the soil, where it moves around according to the permeability of the soil. Protecting those roots from moisture and possible damage would be nearly impossible. A scholarly article from the USDA Forest Service on Yucca brevifolia (Joshua tree), we found this information on the roots:

"Belowground description: The Joshua tree root system is described as deep and extensive. The enlarged trunk base of mature trees can be almost 4 feet (1.2 m) in diameter but extends only about 1 foot (0.3 m) into the ground, suggesting that Joshua trees are supported mainly by their roots and rhizomes . A large number of small fibrous roots penetrate down and horizontally. In southern Utah, Joshua tree roots were found in an excavation pit in a blackbrush community when the nearest Joshua tree was 36 feet (11 m) away."

Are you prepared to make that much raised bed available? Do you even have the space for a plant that can grow up to 40 ft. tall with branches carrying spiny leaves at the tips? In the above-referenced USDA Forest Service article, the plant's main stalk (or trunk) is considered soft and pulpy, probably not resistant to the sorts of storms you can have in the "toe of the boot" where Livingston Parish is located in eastern Louisiana.

On the bright side, there is Yucca louisianensis (Gulf coast yucca) which grows in a parish near Livingston, so obviously yuccas can grow there, we just don't know if the particular yucca you are interested in can. The whole point in the dedication of the Lady Bird Johnson Wildflower Center and Mr. Smarty Plants to plants native to a specific area is that is where those plants will grow. If you try to grow them somewhere they are not native, it will require an expenditure of resources-money, time, back muscles-and it still might not survive. In these strange climactic conditions and sometimes difficult economic times, you are gambling on a plant doing well where it isn't supposed to be, and if it fails, you have basically wasted those scarce resources (and maybe your back muscles.)