By: Bonnie L. Grant, Certified Urban Agriculturist
Exotic plants like the coral tree lend unique interest to the warm region landscape. What is a coral tree? The coral tree is an amazing tropical plant that is a member of the legume family, Fabaceae. It may be spiny or smooth, deciduous or evergreen, with a spectacle of a flower in brilliant pink, red or orange hues.
Growing coral trees is only appropriate outdoors in USDA zones 9 and up. Coral tree care is easy if you are in the correct region, but some growers may find them messy. Find out how to grow coral trees and add some of their intense beauty to your garden.
Coral trees are members of the genus Erythrina and are primarily found in South Africa and South America. There are approximately 112 different species of Erythrina around the world. They are also found in Mexico, Central America, the West Indies, Asia, Australia and even Hawaii.
The wide area covered by the plants seems to indicate coastal dispersal of seeds. Some interesting coral tree information regards their extremely buoyant seeds, which have the ability to float for up to one year and are so hard they pass unharmed through animal and bird digestive tracts. These tough seeds wind up tossed from surf on fertile tropical soils where they take off and eventually adapt and evolve to take advantage of their environment.
The average height of a coral tree is 35 to 45 feet tall, but some varieties exceed 60 feet in height. The leaves have three distinct leaflets and the stems may have thorns or may be smooth, depending upon their evolutionary adaptations.
The trees have a thick trunk, usually with several smaller trunks joining the main stem. Roots push out of the ground as they age and may become a hazard. The bark is a thin grayish brown and the wood is pithy and weak, prone to breaking in the wind or due to overwatering.
The flowers are the standout, appearing in late winter. They are outlandish constructions of thick bright pedals standing erect around the corolla. Hummingbirds are extremely attracted to the loud colors and striking scent.
Coral trees need very little water. Too much water actually promotes a weak limb structure and subsequent breakage. Overwatering causes the tree to grow too quickly, and its soft wood cannot support such spurts. Then in the dry season, the weight of the tree can actually pull it out of the soil.
Pruning the tree in spring to remove the heavier stems or any damaged material will help prevent limb loss and trees from tipping.
Fertilizer is also not recommended when growing coral trees. Fertilizer also causes them to have aggressive growth that can cause problems later. Cover over the root zone with a good organic mulch, which will gradually leach a light dose of nutrients into soil over time.
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Core Coral tree facts
Name – Erythrina
Family – Fabaceae
Type – shrub
Height – 10 to 20 feet (3 to 6 meters)
Exposure – full sun
Soil – rich enough
Foliage – deciduous
Flowering – May to August
Well the world’s worst tree for dropping huge limbs or falling over is the coral tree – usually called Erythrina indica. This is a weed tree spread by humans: almost any part of this tree will grow into a new tree: broken branches, bits of bark even mulch and wood chips from mulched coral trees will grow.
Recently our electricity and phone lines were cut off for a couple of days due to a coral tree on another near-by property falling on the power lines. If you have a coral tree, get permission to remove it & tell them not to mulch it!
Most trees that drop branches are weakened due to lack of water. Use a sprinkler for 1 hour once a week during summer on ALL trees near houses, power lines or roads. This pays dividends.
fallen coral tree (Erythrina sp.), a frequent occurrence when this tree is planted in a lawn
In the confrontation between people and nature, people tend to prevail.
There has been some controversy as to whether people should rebuild their homes in wildfire areas because of the potential danger of living there. Well, if people leave their homes because of proximity to combustible wilderness, they may as well leave the more built-up areas of Southern California as well, due to the other natural hazards – flood, mudslide, drought and earthquake – that all of us face.
Each time I drive down San Vicente Boulevard in Brentwood, I am reminded of people’s horticultural obstinacy in the face of ecological logic. The parkway median in the center of this wide thoroughfare is planted with coral trees. The coral tree (Erythrina caffra) is a magnificent, muscular-limbed species that loses its leaves in the winter and then, still in leafless condition, produces fiery orange flowers.
The only problem with the coral tree is that it simply cannot support its own weight. It must be pruned at least once a year. The best time to do this would be in March or April, following bloom so as not to sacrifice flower production, but the moment your coral tree looks top heavy, you should prune it, no matter what the season, even if that means pruning every six months. I have seen many fallen or split-apart coral trees over the years, despite their having been pruned on an annual basis.
If you look at the more mature coral trees on San Vicente Boulevard, you will notice that many of the trunks show scars where large branches have broken off. Because of their top-heaviness and brittle wood, coral trees don’t live long. Nevertheless, each time a coral tree on San Vicente Boulevard dies, it is replaced with another. Some would argue that a different, sturdier type of tree should be planted on this median. Yet so beloved are the Brentwood coral trees by the surrounding residents that it has been written into the city’s specific plan that “no major alteration of the (San Vicente Boulevard) median strip shall occur without a public hearing.”
Ironically, perhaps, the coral tree, which is native to South Africa, has been designated the official tree of the city of Los Angeles. Some would change our city’s official tree to a native species of oak, for example, but others insist that since nearly all our city’s residents (or their parents) came from somewhere else, it is only proper that the city’s official tree should also be an import.
Q: Our navel orange tree is about 25 years old and this year we are experiencing the ripened fruit splitting. Do you know what the cause may be?
A: Split citrus fruit is a common phenomenon and is not a sign of disease. Split fruit is perfectly edible as long as you pick it before fungi or insects find their way inside. The usual cause of split fruit is too much water. Over-irrigation of orange trees – and of all other citrus, for that matter – is common. Even in hot weather, citrus should not be watered more than once every other week. When you do irrigate, water deeply by allowing a trickle of water to soak the root zone for 12 to 24 hours, depending on how quickly your soil drains.
Splits are occasioned by rapid growth of the fruit pulp at the expense of the peel. A sudden increase in water uptake by the tree, made possible by heavy irrigation after a dry spell or by a sudden rainstorm, could cause accelerated growth and expansion of the fruit pulp to where it splits the peel.
Q: I would like to plant a nonflowering shrub that would grow to a height of 8 to 10 feet and serve as a screen along my property line. I am going to use a soaker hose for irrigation. What would you plant and what should the spacing be?
A: The most dependable hedge plant in the Valley for an 8- to 10-foot high screen is Texas privet (Ligustrum japonicum ‘Texanum’). This plant is not drought tolerant, however, so it is wise that you will have a soaker hose in place for irrigation. You can plant your privets every 3 to 5 feet along your property line, depending on how quickly you want your hedge to fill in. Texas privet does flower briefly in mildly fragrant panicles of white, but flowers are not significant and may be sheared off in the course of pruning your hedge.
TIP OF THE WEEK: The best bedding plant for planting in the shade this time of year is cyclamen. Cyclamen has silky flowers in white, pink, rose, lavender and red. Cyclamen is pricey, up to five times more expensive than primroses, which are also recommended as cool-season bedding plants for the shade. Primroses, however, are more attractive to snails and more susceptible to chlorosis than cyclamen. Cyclamen are also more long-lasting than primroses and should continue blooming until March or April.
Members of the family Fabaceae (Pea) family, coral trees are large, deciduous trees that grow to between 12 and 18 metres tall.
Also known as flame trees, their pea pod-shaped flowers vary from red to deep orange in colour and bloom in clumps during spring, before foliage starts to form. The light-brown bark of the tree is characterised by a scattering of rose-like thorns.
Though coral tree seeds are infertile, the plant spreads through cuttings, roots or plant fragments that are buried in soil. Hardy in a range of North Island conditions, the coral tree grows fast, lives for a long time and has dense foliage which prevents native plants from become established.
Remove younger coral tree plants, making sure you dig up all roots. Once out of the ground, leave the plant to rot on concrete surfaces. Be careful not to leave any soil on the plant as it can easily re-establish itself.
To eradicate established coral trees, cut them back and then immediately paint with MetGel or picloram. Be careful not to paint other plants – particularly native species.