When these long-lived plants mature, they develop distinctive extensive branching with rounded, open crowns (usually when they reach between 3 and 9 feet in height). The foliage develops in rosettes on the tips of the branches. However, young trees grown in a garden setting will usually lack branches and have bent backwards leaves.
The creamy-white, small flowers that cluster at the ends of long panicles develop into light green seedpods. This species provides an important food source and shelter for birds and small mammals in its harsh native environment.
These trees are only suitable for growing in areas with similar conditions to their dry, desert native habitat. They are sometimes grown in desert gardens, xeriscape landscapes, and rock gardens. As a specimen plant, their unusual, architectural shape makes a bold focal statement.
Joshua trees can be hard to find, and purchasing from a reputable supplier is important to ensure the trees or seeds are not from protected, wild populations. It’s best to plant these trees from November to March—they don’t have a good recovery rate if you transplant them when the weather heats up.
The rhizomatic root system of these trees is deep and vast. They need plenty of space to grow—keep them away from the home foundation and any pipes or utilities. Think carefully about the position as Joshua trees don’t transplant well.
Light
As you would expect of a tree native to the desert, it needs a full sun position to thrive.
Soil
Joshua trees can grow in sandy, loamy, rocky, and clay soils, but they must be well-drained and dry. Unlike many plants, the poorer the quality of soil, the better they are likely to grow. Fertile, rich soil is not the Joshua tree’s friend.
Water
This is a highly drought-tolerant tree. Established Joshua trees only need supplemental watering in periods of drought. When the ground is dry, dusty, and crumbly to the touch, you can water until the soil is saturated. Don’t water it again until it fully dries out, at a maximum of once per month during the growing season. Overwatering can lead to root rot.
Temperature and Humidity
For your Joshua tree to survive, the climate should replicate the extreme, elevated Mojave Desert as closely as possible. It needs a scorching hot, dry summer and a cold winter. Without a dormant period, the tree will die, so these changes in temperatures are important. They can tolerate winters as cold as 12 degrees Fahrenheit and summers as hot as 120 degrees Fahrenheit. It’s certainly not a tree for growing in the tropical, humid southern regions or in areas with high volumes of rainfall.
Fertilizer
Wild Joshua trees thrive in poor, infertile soils, so they shouldn’t need supplemental feeding. Fertilizing may encourage faster growth, but this can alter the naturally appealing form of the tree. If you want to use fertilizer, select a slow-release type suitable for desert plants or a mild, slightly acidic organic option like a fish emulsion. It won’t need regular feeding—an annual dose or one in late spring and early fall is sufficient.
Types of Joshua Tree
This is not a highly cultivated species, but if you’re looking for a compact version of the tree for a smaller landscape, you can opt for Yucca brevifolia var. jaegeriana. This dwarf tree version typically grows to around 10 feet and has shorter branches than the standard Yucca brevifolia.
Pruning
Part of the appeal of the Joshua tree is its distinctive natural form—it won’t need any pruning other than to remove any old, damaged flowering stems. By leaving the branches with dry leaves, they can insulate the plant in cold winters by absorbing moisture.
How to Grow Joshua Tree From Seed
Growing Yucca brevifolia from seed is tricky but not impossible. The flowers can only be pollinated by a species of moth native to the trees natural habitat, so hand-pollination using the likes of a small paintbrush is often necessary. For best results, you should sow fully ripe and fresh seeds.
Potting and Repotting
Joshua trees are slow-growing, but they do have an extensive root system. If they are being grown in a container, you should repot them in a larger pot every few years at the end of winter. Because they don’t like being transplanted, you need to do this very carefully.
How to Get Yucca Brevifolia to Bloom
When a Joshua tree is in flower in spring, it produces densely clustered panicles that can be up to 20 inches long. The small, individual, white-green flowers are oval-shaped and have an unpleasant, mushroom-like fragrance. Not every tree flowers annually. There needs to be perfect weather conditions to facilitate flowering, and not every tree will bloom annually. Freezing winter conditions stimulate the following season’s flowers. Too little or too much rainfall can also impact blooming success rates.
