The coral bean shrub (Erythrina herbacea) grows easily at a moderate rate and requires little attention once established. It is most commonly found in the southeastern United States and northeastern Mexico. It bears bright red, tubular flowers during spring, summer, and fall. The foliage of the coral bean is heart-shaped and glossy dark green, and its trunk and branches are covered in small curved thorns. Despite its beauty, the coral bean is highly toxic to humans and pets.
|Common Name||Coral bean, red cardinal, cardinal spear, mamou plant|
|Botanical Name||Erythrina herbacea|
|Plant Type||Perennial, shrub|
|Mature Size||8–10 ft. tall, 3-6 ft. wide|
|Sun Exposure||Full, partial|
|Soil Type||Sandy, well-drained|
|Soil pH||Acidic to neutral|
|Hardiness Zones||8–11 (USDA)|
|Native Area||North America, Central America|
|Toxicity||Toxic to humans , toxic to pets|
Coral Bean Care
The coral bean is native to Mexico and parts of the United States. It is a low-maintenance perennial shrub that readily grows in warm climates worldwide. Once established, the coral bean requires little maintenance. As a result, the coral bean is an excellent addition to a garden bed or shrub border. The coral bean shrub is also salt-tolerant, making it an ideal choice for gardeners living on coastal landscapes.
Plant your coral bean in late spring or early summer. During the winter, place your coral bean in a greenhouse. If left out, the plant will die in hardiness zones cooler than 8, such as in the Northeast.
Coral bean shrub blooms best in full sun for four to six hours daily, but it can tolerate partial sun, as it naturally occurs along the edge of woodlands and forests.
Coral bean is adaptable to a wide range of soil types but thrives in sandy, acidic soil. If you're planting coral beans in a clay-rich area, supplement the soil with coarse sand.
Water the coral bean once a week for the first growing season to encourage growth. The shrub does not tolerate excess wetness and should never be waterlogged. Once established, the coral bean is a drought-tolerant shrub and requires only supplemental watering during abnormally long dry periods. Be mindful of inadequate rainfall.
Temperature and Humidity
The coral bean requires warm temperatures and thrives in USDA zones 8-11. In regions that experience cold winters with freezing temperatures, the coral bean can be grown as an annual rather than a perennial.
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, slow-release product. 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 benefits from light yearly maintenance. Do not prune during the first growing season. In the spring of the second growing season, you may 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. You can take semi-hardwood cuttings in the late summer or early fall once the stems 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. Here's how to propagate coral bean:
- Cut a 4-6 inch section of a hardened, brown area of the stem
- Clip any seed pods or flowers from the cutting and an inch of bark from the bottom
- Dip the cutting into a rooting hormone
- Create a mixture of peat moss and coarse sand and insert the cutting into the pot
- Water and cover with plastic to retain moisture
- Place the pot in a shaded area
How to Grow Coral Bean From Seeds
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. Always wear protective gloves when handling coral bean seeds, as the seeds are toxic (primarily if ingested). Coral bean seeds benefit from scarification to increase the germination rate. Plant seeds in the ground after the threat of frost and once the temperatures are consistently warm. When planting several shrubs together, ensure you sow the seeds between 3-5 feet apart.
Potting and Repotting Coral Bean
Coral bean may be grown in a container. It is best placed in full sun with southern exposure. Be sure to protect it from freezing during cold weather. Ensure that the potting medium is well-draining as the coral bean’s roots cannot tolerate sitting in water.
Coral bean is evergreen in tropical climates but will die in freezing winter temperatures. However, it will regrow in the spring. You may overwinter coral bean indoors, preferably in a greenhouse.
Common Pests & Plant Diseases
Coral bean is susceptible to infestation by a variety of moths. The shrub is relatively unaffected by disease but can develop funguses and root rot. Leucoptera erythrinella are particularly harmful to the coral bean.
How to Get Coral Bean to Bloom
The best way to ensure coral bean bloom is placement in full sun. Bloom occurs between May and June. To encourage growth, trim dead stem tips in the spring or frostbitten stems in cooler months. Bloom produces bright red, glossy flowers with arrowhead-shaped leaflets. The flowers grow in clusters, extending to about 12 inches in length. Hummingbirds will often feed on the bloomed coral bean.
Common Problems With Coral Beans
The problems you may have with coral beans are common to most shrubs. While the plant is relatively simple to care for, pay attention to issues like yellowing, browning, and wilting. Occasionally dust your coral bean to ensure proper photosynthesis and discourage discoloration.
Yellowing is the most common issue related to coral bean growth. Usually, this is caused by overwatering or inadequate nutrients like potassium, nitrogen, magnesium, and iron. Sunburn can also cause yellowing, in which case, move your plant to a slightly shadier area.
Browning on a coral bean can usually be attributed to dehydration or overexposure to direct sunlight. Consider adjusting your watering routine and placing your plant in a different location.
Wilting is typically caused by dehydration. If your coral bean is particularly large, it will require more water than a smaller plant.
Where should I place coral bean?
You can place a coral bean plant in your garden among other shrubs. Make sure your plant has adequate sunlight to grow properly.
What are coral bean alternatives?
Due to the high toxicity of coral bean, you may want to seek an alternative if you're concerned about children or pets around the plant. Another brightly colored, narrow-flowered, non-toxic shrub option is the butterfly bush (Buddleja davidii).
Does coral bean have a scent?
Coral bean is not considered to have a distinct scent. Although you may want to put your face close to the plant to smell, close contact is dangerous.