Creosote bush is a flowering plant and is a prominent species in the Larrea genus of shrubs. Native to desert lands in western North America, this evergreen shrub commonly grows in well-drained soil, covering large areas of terrain.
This perennial is known as the creosote bush because it exudes a smell of creosote. This is the reason that in Spanish, L. tridentata is called “hediondilla”, as it translates as smelly. Larrea tridentata is one of the most prolific shrubs growing in the North American deserts.
Until around ten years ago, botanists thought that the creosote bush roots contained a chemical that spread to neighboring plants to inhibit their growth.
However, it seems that in fact, the roots of mature creosote bush shrubs are just extremely effective in absorbing what little water they can find in the dry, arid conditions in which they survive.
Neighboring plants and their seeds can’t compete successfully enough to germinate and grow.
The botanical name of the genus “Larrea” is named after the Spanish scientist, Juan Antonio Perez de Larrea. The creosote bush is a very long-lived plant. It forms clone rings and in the Mojave Desert there is a colony of Larrea tridentata clones believed to be over 10,000 years old.
|Scientific name||Larrea tridentata|
|Common names||Creosote bush, greasewood, chaparral, hediondilla (in Mexico)|
|Height||3 to 10 feet (up to 3.05 m)|
|Width||3 to 10 feet (up to 3.05 m)|
|USDA Plant Hardiness Zone||Zones 7 to 11|
|Native to||North America deserts|
|Blooming season||Spring and Summer|
|Flower colors||Yellow and white|
|Plant specific features||Long-lived, drought tolerant, evergreen|
How to Plant and Grow a Creosote Bush
Where to Plant
Due to its drought tolerance, this is an excellent choice for xeriscaping. An established creosote bush can survive for two years with no water!
Choose Larrea tridentata for planting in a rock garden, desert garden, or anywhere where water supply is scarce or inaccessible. It can be used in an informal or cottage type of planting scheme, as well as an addition to a mixed border. Multiple creosote bushes can also be planted to form a hedge or privacy screen.
When to Plant
It’s in the fall that is the best time to plant a creosote bush shrub. This is a slow-growing shrub. Planting in the fall will enable the plant to use the winter rains to establish the extensive network of tap and lateral roots before the onset of the extreme heat of summer.
Creosote Shrubs Care and Maintenance
The soil needs to be well-draining and L. tridentata will perform best if planted in a sandy, rocky, or gravelly type of soil. This shrub will tolerate coastal locations, due to its saline tolerance. The pH level isn’t important, as the creosote bush will grow in acid, neutral, or alkaline soil.
Creosote bush seedlings, or newly planted shrubs need to be watered regularly in order that they can develop their exceptionally efficient root networks.
Once mature, their watering needs are very, very low. Creosote bush shrubs can survive up to two years without water!
However, if you provide a little water once a month, it will flower more abundantly and for a longer period. But don’t over water, or it will grow tall and leggy.
If you provide L. tridentata with this supplementary irrigation, it will grow taller and fuller. But, take care not to over water.
Ensure that the soil drains freely, and doesn’t remain wet. If the shrub sits in wet soil, it will die.
It is after rain (or watering) that the creosote bush releases its distinct odor, which resembles the strong smell of the chemical creosote.
Although there is some conflicting opinion, the vast majority of advice for successfully growing creosote bush shrubs advocates no fertilizer application.
Not only is it suggested that the shrub doesn’t need fertilizer, but rather that it actually will harm the plant. Application of even a diluted liquid fertilizer can result in a yellowing of the leaves and even leaf loss.
This, coupled with its drought tolerance, makes L. tridentata a good plant if you are looking for an evergreen shrub that doesn’t require much human intervention!
If you have a garden that receives plenty of hot sun in the daytime, your creosote bush plant will be very happy. In the spring, summer, and even possibly in the fall, L. tridentata will produce scented yellow flowers followed by seed pods.
Creosote bush is a desert native shrub; mimic these conditions for the best results with this plant. Sunshine and very little water – nothing else!
Pruning and Repotting
In the wild, creosote bush shrubs will grow and self-seed without any human intervention. But, their branches can become brittle and break. In a garden environment, you will want to rid the plant of dead and damaged wood to promote a healthy shrub.
If it becomes too dense in the center (which it might do if you provide supplementary watering), you can thin it in order to improve airflow and reduce humidity.
Once the plant is mature, it is tolerant to hard pruning. If it is cut down to ground level, new and vigorous growth will form the following season. Similarly, the creosote bush shrub can be shaped to create an attractive form, by pruning.
It is difficult, but not impossible, to find a creosote bush plant available for sale.
Sometimes you can find rooted cuttings in which case you need to plant them as soon as possible and keep them moist for the time it takes to develop a root system. You are unlikely to be successful with this method of propagation if you don’t plant them immediately.
But propagation from seed is not difficult, provided you soak the seeds in boiling water and leave them in the water for 24 hours. This will soften the hard seed coating and improve the success of germination.
You can then sow the seeds in individual pots, keeping the pots damp until the seeds germinate. Once the seedlings appear, move the pots to a sunny and warm spot and keep them moist until a small but complete root system has developed.
Before planting the creosote bush seedlings outside, harden them off gently to acclimatize them to the conditions. It is best to plant them in a nursery bed, the soil of which is mixed with plenty of sand, gravel, or grit.
If they are left in a nursery bed and kept moist, they will establish strong root systems before being transplanted.
Pests and diseases
Although the creosote bush is a native plant that is considered to be pest free, there are insects that can cause minor damage to the shrub.
Leaf yellowing can be the result of too much water or following the application of fertilizer. Leaf distortion is most likely to be caused by insects and other pests, such as spider mites, or stink bugs.
Stink bugs are difficult to kill unless they are removed by hand. They have mouths that can pierce through the foliage, thereby damaging it.
Because spider mites are so small, they can be difficult to identify, and their eggs are just the size of little specks of dust!
Spider mites can find the leaves of the creosote bush attractive due to their succulent nature. Providing your creosote bush with less water will reduce the succulence in the leaves and make them less desirable to spider mites.
If you can spot the spider mites early on, before they colonize, you can usually eradicate them by spraying the leaves with soapy water. If, however, they have got control of your shrub, it is much harder to eliminate them, especially during hot weather.
Traditional pesticides can worsen the problem, as they will also kill the beneficial insects that would feed on the spider mite.
Temperature and Humidity
The leaves of the Larrea tridentata are pointed and waxy. They have evolved to withstand drought and extremely high temperatures.
A mature plant doesn’t just develop a single tap root, but a complete network of tap roots that start around 18 inches (45.72 cm) below the soil surface. This makes them aggressive and successful competitors with other plants in their search for profound, in-ground moisture.
Creosote bush shrubs grow well in dry conditions and in hot sunshine. It will thrive even if there is a 20 °C difference between the day and night temperatures. Hot sunshine is essential, though.
Other Uses for Creosote Bush
In the desert, creosote bush standings can provide mammals with important cover, and resting sites. During excessive heat and sun, however, creosote bush shrub does not provide very effective shade, particularly for large animals.
Other creatures feed on the foliage, and birds use the branches to perch and roost.
The roots of the creosote bush control soil stability in areas where the ground is very dry and dusty. Small mammals and rodents form burrows and tunnel networks in the root systems beneath the creosote bush, in order to protect themselves from predators.
The creosote bush produces seeds following the flowers, and these, as well as the tips of new growth, provide a food source for some small rodents and mammals.
However, L. tridentata is not favored by most browsers, including deer. The strong scent of the flowers is an animal deterrent, and this is an important factor in the plant’s exceptionally long life span. Creosote bush shrubs can often live for over 100 years.
Creosote bush shrubs were valued for medicinal purposes by the desert natives. Both twigs and leaves were processed and used to treat many diseases.
Desert people also extracted a sticky product rather like sealing wax from an insect larvae deposit that stuck to the stems of the creosote bush. This lac was used to seal the lids of jars in food preservation.
Types of Creosote Bush You Can Grow
Larrea tridentata or creosote bush is one of the five evergreen species in the Larrea genus. It is this shrub that is the most notable of the genus.
This plant is recognizable by its distinct aroma after it has rained. It’s not only a tough and robust desert native, but it is also pretty too!
With its elegant habit, graceful foliage, yellow flowers in spring, and fluffy seed pods, Larrea tridentata will provide you with year-long pleasure – and with hardly any additional input from you!
*image by gioiak2/depositphotos