The coral bean shrub (Erythrina herbacea) is easy to grow, grows at a moderate rate, and requires little attention once established. It is attractive and showy with almost year-round interest. The coral bean is adorned with gorgeous ornamental, tubular flowers. In the summer and into the fall, the flowers turn into long pods with brilliant red seeds inside. The foliage of the coral bean is heart-shaped and glossy dark green. The trunk and branches are covered in small curved thorns. The tubular flowers are also highly attractive to hummingbirds drawn to the sweet nectar inside them. Only plant this shrub in the ground in hardiness zone 8 (Pacific Northwest or American South) or higher or else it will die. The best time to plant it is in the spring.
|Botanical Name||Erythrina herbacea|
|Common Name||Coral bean, red cardinal, cardinal spear, mamou plant|
|Plant Type||Perennial, shrub|
|Mature Size||8–10 feet tall|
|Sun Exposure||Full, partial|
|Soil Type||Sandy, well-drained|
|Soil pH||5.4 to 7.6 (acidic to neutral)|
|Hardiness Zones||8–11 (USDA)|
|Native Area||North America, Central America|
|Toxicity||Toxic to humans and pets|
Coral Bean Care
The coral bean is native to Mexico and parts of the United States. It is a low-maintenance flowering perennial shrub that readily grows in warm-season climates around the world. Once established, the coral bean requires little maintenance. As a result, it makes a great addition to a garden bed or shrub border. The coral bean shrub is also salt-tolerant, making it an excellent choice for gardeners living on coastal landscapes.
For the winter, place the coral bean plants in a greenhouse and plant in late spring or early summer. If left out, the plant will die in hardiness zones cooler than 8, such as in the Northeast.
The coral bean shrub blooms most profusely when grown in a full sun location. However, it can tolerate dappled sun, as it naturally occurs along the edge of woodlands and forests.
The coral bean is adaptable to a wide range of soil types but appreciates sandy, acidic soil. Ensure that the potting medium is well-draining as the coral bean’s roots cannot tolerate sitting in water.
For the first growing season, water the coral bean once a week to help encourage growth. This shrub does not tolerate "wet feet" and should never be left waterlogged. Once established, the coral bean is considered to be a drought-tolerant shrub and may only require supplemental watering during abnormally long dry periods.
Temperature and Humidity
To survive as a perennial, the coral bean requires warm temperatures and thrives in USDA zones 8 through 11. In regions that experience cold winters with freezing temperatures, the coral bean can be grown as an annual.
Once established, the coral bean shrub does not require regular fertilizing. However, young plants benefit from fertilization in the spring to help boost growth. Use a balanced fertilizer, such as a 10-10-10. This shrub also benefits from annual mulching to help retain moisture and protect the sensitive root system from cold temperatures.
The coral bean does not require heavy pruning but appreciates light yearly maintenance and general upkeep. Do not prune during the first growing season. In the spring of the second growing season, prune any dead or cold-damaged growth and trim to shape where necessary.
Propagating Coral Bean
You can propagate the coral bean shrub via semi-hardwood cuttings and division. Semi-hardwood cuttings can be taken in the late summer or early fall, once the stems are almost fully mature. The shrub can technically be propagated by division of the root ball at any time, but it is best to do so once the coral bean is well established with excess growth that you can easily separate. At the same time, both methods can successfully propagate the coral bean. It is usually most efficient to start with a nursery-grown plant or well-established shrub as propagation success rates are variable.
How to Grow Coral Bean From Seed
Coral bean seeds can be purchased from a nursery or garden center or collected directly from the plant. You can collect the seeds in the late summer or early fall. Be sure to always wear protective gloves when handling coral bean seeds as the seeds are poisonous (primarily if ingested). To increase the germination rate, coral bean seeds benefit from scarification. Plant seeds in the ground after the threat of frost and once the temperatures are consistently warm. If you are planting several shrubs together, ensure the seeds are spaced between 3 to 5 feet apart when sowing.
Potting and Repotting Coral Bean
Coral bean may be grown in a container, usually in the northern states. It is best placed in full sun with southern exposure. Protect it from freezing.