The foliage on this species is a bipinnately compound, meaning that each leaf consists of up to 25 pairs of leaflets, and each of those leaflets is further divided into up to 25 more pairs of leaflets. This tree is renowned worldwide for its clusters of exquisite red flowers that blanket the tree in the warm summer months. Each of the five petals is reddish-orange or scarlet. One petal is bigger than the others and has yellow and white markings. The fruit is a seed pod that can be over a foot long. After planting, cover the soil around the tree—leaving some space near the trunk—with a 2-inch layer of mulch.
Light
These trees do best in full sunlight, so choose an area that gets at least six full hours a day. Without adequate light, you might not see the showy red-orange flowers for which the flame tree is known.
Soil
A flame tree will grow in a variety of soil conditions as long as there is good drainage. The tree will tolerate clay, loamy, sandy, or gravelly soils in a wide pH range between 4.9 and 10.6.
Water
After planting, water the tree regularly during the spring, summer, and early fall. Keep the soil moist, but never soggy until the roots become established. Make sure that the soil dries out between waterings. During the late fall months, gradually cut down on the water supply before stopping extra watering during the winter months when the tree goes dormant.
Temperature and Humidity
The flame tree is native to tropical forests, so it does well in warm, humid environments. It cannot tolerate temperatures below 45 degrees Fahrenheit. It’s easily grown outdoors in parts of Florida, Texas, and Hawaii. It is only suitable for reliably warm climates.
Fertilizer
Give the tree a balanced liquid fertilizer for four to six weeks after planting and then two to three times per year for the first three years. Give an additional application in early spring and fall. For the amount to use, follow the product label instructions. Water the tree thoroughly after the soil has been fertilized.
Types of Delonix
Other flowering trees in the Delonix genus include:
Delonix elata (White gul mohur, creamy peacock flower) with smaller flowers than D. regia. The flowers are white and fade to yellow. The tree reaches 30 ft. in height and it is very drought-tolerant.D. floribunda (Yellow poinciana), a small- to medium-size, drought-tolerant tree with greenish-white flowers and a thick, swollen trunk. It is suitable to be grown as a potted tree indoors and trained as a bonsai.
Pruning
It’s important to prune flame trees to create a strong tree structure, as the limbs are susceptible to breakage in high winds. Around late March or early April, or right before spring growth starts in your area, prune any major branches that are half the diameter of the trunk or below 8 to 12 feet from the ground.
Propagating Flame Trees
Seed germination and cuttings are used to propagate this tree. To propagate the tree from cuttings:
Growing From Seeds
The seeds can be germinated and seedlings planted at any time but the seeds will need to be scarificed first to break open the seed coat and allow water to germinate the seed (see techniques below). If you already have a flame tree, harvest the long, strappy dark brown seed pods when they fall to the ground in the spring.
Growing in Pots
The flame tree is too big to be grown in containers but it can be grown and trained as a bonsai. As such, it will require potting every two years.
Overwintering
The flame tree can’t tolerate frost as it will rot the roots. If there is ever the danger of frost in the typically no-frost zones of 10 to 12 (USDA), cover smaller trees with burlap or a tarp overnight.
Common Pests and Plant Diseases
Although flame trees don’t have a lot of pests, some species of caterpillars may chew away on the leaves. However, it should not defoliate the entire tree. Additionally, spider mites can be an issue, particularly if the tree isn’t in a humid environment. If you spot spider mites, increase the humidity or set the plant outdoors. Scale insects can also be an issue. They’ll appear under the leaves, but can be removed with cotton swabs dipped in alcohol. Phellinus noxious is a fungus that may cause the roots to rot. Choosing a spot with soil that drains well can help lessen the possibility that this fungus will invade.
How to Get Flame Tree to Bloom
If your flame tree isn’t blooming, it might not be mature enough. It can take six to ten years for the tree to bloom for the first time. Another reason for its failure to bloom can be insufficient sun; the tree needs full sun to bloom.
Common Problems
Litter will happen if the branches (which are brittle) break or when the seed pods fall to the ground. You can help reduce the chances of the branches breaking if you can provide a spot with protection from winds and prune to form a strong branching structure. The tree has a shallow root system, which not only competes with neighboring plants for space, but also makes the tree prone to being uprooted in strong winds.
