Cassia

( KASS - ee - uh )

At-A-Glance Information

Commonly called Cassias, these medium to tall trees are native to tropical areas around the globe. Some trees are deciduous, while others in the genus are semi-evergreen to evergreen. These trees produce impressive shows of dangling flower inflorescences in late spring and summertime. Blooms are typically yellow, but can also be white to pink-purple in some species. Take care when planting these trees in your landscape; the seeds of some species are toxic if ingested. Use low-maintenance Cassia trees as specimens (valued for their gorgeous shows of flowers), as ornamental trees in gardens or parks, as street trees, or as shade or pollinator trees. Some species of Cassia are also wonderful for controlling erosion on sloped areas or where soil stabilization is needed.

Cassia Species and Varietals

The genus Cassia is a member of the plant family Fabaceae and includes 37 species. Cassias typically grow best in USDA hardiness zones 9-11 or Sunset growing zones 15, 16, 20-24, H1 and H2. To find your zone, click here: Zone Map.

Cassia abbreviata (Sjambok Pod, Lon-Tail Cassia, Long Pod Cassia, Wild Senna, Muvheneka)
Native to a wide range on the African continent, this species forms a tree that reaches between 7 and 50 feet tall at maturity, depending on growing conditions. Foliage is green, and bark is rough and greyish-brown. Flowers are yellow, and are followed by very long seed pods, which dangle from the tree and are quite conspicuous.

Cassia bakeriana (Pink Shower Tree, Wishing Tree, Dwarf Apple Blossom Tree)
​This species of Cassia reaches about 30 feet tall when mature and produces profuse shows of white to pinkish-purple flowers. These trees are native to Myanmar and Thailand, and are commonly grown as ornamentals around the world. This species is considered invasive in south Florida and regions in Australia, Kenya, and Uganda.

Cassia fistula (Golden Shower, Purging Cassia, Indian Laburnum, Kani Konna, Pudding-Pipe Tree, Amaltas, Bahava)
This species of Cassia is native to the Indian subcontinent and adjacent areas in Southeast Asia. This tree is the official state tree of Kerala and Delhi and is a popular ornamental tree grown in the surrounding area. These are medium-sized trees that bloom in spring and summer and appreciate large differences between winter and summer temperatures. Trees in this species reach up to 20-40 feet tall when mature. This species is considered invasive in Queensland, Australia.

Cassia grandis (Pink Shower Tree, Carao, Coral Shower, Horse Cassia, Stinking Toe)
Reaching up to 100 feet tall at maturity, these trees are native to southern Mexico, Venezuela, and Ecuador. They grow in low forests and are cultivated to make a culinary sweetener in their native range. This species is considered an invasive tree in Australia, Malaysia, Java, and New Guinea.

Cassia javanica (Java Cassia, Pink Shower, Apple Blossom Tree, Rainbow Shower Tree)
These fast-growing deciduous trees are native to Southeast Asia, and are grown worldwide as ornamental trees due to their beautiful, profuse shows of flowers. Individual trees reach up to 80-130 feet tall and 33-65 feet wide when mature. Blooms are crimson and pink, and there are various cultivars and subspecies with varying flower colors. Java Cassia is considered invasive in Mexico, Nicaragua, the Dominican Republic, Hawai'i, Malaysia, and the Philippines.

Cassia leiandra (Mari-Mari, Marimari-Da-Varzea, Fava-Marimari)
This species of Cassia is native to Colombia and Brazil, and has been introduced to Uganda. The succulent, bittersweet fruits are cultivated and sold in markets in the Amazon. These trees typically reach between 20 and 45 feet tall when mature, and have divided green foliage. Flowers are yellow. 

Cassia leptophylla (Gold Medallion Tree)
These trees produce profuse shows of golden yellow flowers throughout the year. Individual trees reach between 20 and 30 feet tall when mature. Gold Medallion Tree is native to southeastern Brazil, and is considered invasive in Australia. This species also produces toxic seeds and other plant parts.

Cassia marksiana (Marks Cassia, Cigar Cassia, Brush Cassia, Native Laburnum)
These trees are native to northeastern New South Wales and southeastern Queensland, where they grow along coastlines and in lowland tropical rainforests. These trees are endangered; there are an estimated 100 left in their natural habitat. This species produces small to medium-sized trees can reach 82 feet tall and have yellow flowers. Marks Cassia is considered to be invasive in Australia.

Cassia moschata (Bronze Shower, Bronze Shower Tree, Musk Cassia)
Native to southern Mexico through northern areas of Brazil, these trees have also been introduced to Sri Lanka. It is a popularly-grown street tree in many Brazilian cities, with its profuse shows of reddish-bronze flowers that dangle from tree branches. This species is considered invasive in Sri Lanka and the northeastern United States.

Cassia queenslandica (Yellow Shower)
Found only in Queensland, Australia, these beautiful trees produce light yellow flowers. These medium-sized trees reach between 20 and 30 feet tall when mature. 

Cassia roxburghii (Red Cassia, Roxburgh's Cassia, Ceylon Senna, Red Laburnum, Rose Cassia)
These trees are native to the Indian Subcontinent and adjacent areas of southeast Asia. The species is named for the Scottish botanist William Roxburgh. At maturity, these trees reach between 50 and 65 feet tall. Flowers are rose-red, orange, or pink (often a combination of these colors).

Cassia sieberiana (Drumstick Tree, Sindia, Sinjan, West African Laburnum, Sieber's Cassia)
These trees reach between 32 and 66 feet tall when mature, and produce bright yellow flowers. The species is native to Senegal, Uganda, Sudan, and various areas of eastern Africa. Bark is dark brown to black. These trees are considered invasive in Australia.

Cassia tomentella (Velvet Bean Tree, Velvet Cassia)
Native to Queensland, this species is a widely used street tree across Brisbane. Grown as large shrubs or medium-sized trees, these plants can reach up to 33 feet tall when mature. Flowers are yellow and foliage is green, and the branches have a somewhat pendulous nature when untrimmed. 

Caring for cassia

These trees should be planted in a spot in the landscape that receives full sun. Cassia requires between 6-8 hours of direct sun daily to flower and grow well. These trees can grow in a variety of soils, including sandy, loamy, and slightly rocky. Soil must drain well and have a slightly acidic to neutral pH (between 6.0 and 7.5). If local soil is overly clayey, it will need to be amended with sand or organic matter in order to make it well-draining. After planting, mulch around the base of the tree, ensuring that mulch stays about 3 inches away from the trunk. Water newly installed trees regularly to help them establish a strong root system. Once mature, these trees are drought-tolerant., benefitting from deep waterings during elongated periods of drought. Avoid overwatering, and allow soil to dry out between waterings to discourage root rot issues. 

Prune young trees in order to create a single-trunked tree. Yearly pruning for cleanup should be done after the main blooming period in summertime. These trees can be pruned to control their shape and size, so that they stay the right height for smaller gardens. Prune lightly and avoid removing too much foliage at any one time, as this can reduce flowering for the year. These trees should be putting on growth at a moderate to quick pace, depending on the species and growing conditions. They can take between 10 and 40 years to reach full height. Pods that follow flowers can be left on the tree for ornamental purposes, or trimmed off if desired (especially if you do not want more trees). The seeds can germinate well under the right climate conditions, so having a lot of volunteer seedlings is common around the base of mature trees. Cassia trees can last for decades in the landscape before needing to be replaced.

Propagation

Cassia can be propagated either by using cuttings or from seed. To ensure that your propagated plant will have the exact same qualities and characteristics as the parent plant, use the cutting method. If you would like to experiment and see what plant you can grow from seed, just keep in mind that it will not necessarily be the same as the parent plant. To propagate your Cassia tree, follow the instructions below:

Propagating Cassia by Cutting
  1. Gather your materials. You'll need a clean, sanitized, sharp pair of garden shears, rooting hormone, a pencil, and a 3-inch pot filled with well-draining compost or other organic material. A good substrate for propagation of cuttings is a light blend of 1/3 pasteurized soil or compost, 1/3 sand, vermiculite or perlite, and 1/3 coconut coir or peat moss.
  2. In spring or early summertime, choose the plant that you'd like to propagate. Ensure that this plant has had a good watering the night before, as this will improve the chances your cutting will take root. Cut one or more 6 inch portion(s) of the end of a non-blooming branch and strip the leaves off of the lower half. Make a hole in your planting medium by pushing your pencil into the soil. Dip the end of the stem in rooting hormone, and plant it in your pot. Fill in soil around the cutting to support it, but do not pack it down too much.
  3. Moisten with water, and ensure that the pot has good drainage. Your pot should be kept in warm, sunny conditions indoors (and not in direct sunlight). Water whenever your soil is dry under the top layer. After about four to six weeks have passed, your cutting should be rooted. When you notice new growth, you'll know you have roots. 
  4. Keep your new plant in an area with bright light (though not direct sunlight) and temperatures between 55 and 70 degrees Fahrenheit. Ensure that the soil stays moist, but not wet, until the next spring, when you can transplant it to its new home. Ensure that the last frost of the year has occurred before doing this, as it can seriously damage your new shrub.

Propagating Cassia by Seed
  1. Keep in mind that the plant you get from seed will not necessarily mimic all of the characteristics of the parent plant. To propagate by seed, you will need a paper bag, a pot or tray filled with well-draining compost or other organic material, a spray bottle and a fork. The best potting medium for seed germination is a light blend of 1/3 pasteurized soil or compost, 1/3 sand, vermiculite or perlite, and 1/3 coconut coir or peat moss.
  2. Harvest your seeds. The seed pods on Cassia plants are pretty easy to spot, they're long, dark and dangle from the branches, left behind after flowers have faded. Once they have dried out and begun to split open, you can harvest the seeds inside. Cut them off of the plant, placing them in a paper bag. Harvest as many as you can, and place the paper bag in a dry, cool, dark area. They will begin to split open and release the seeds contained inside. Once they have been released, take them out of the bag and put them in a container so you can work with them.
  3. Cassia seeds have a hard coating that protects them, but this coating also makes it a little difficult to get them to germinate. We can help the process along by scarifying them with sandpaper (or simply rubbing them against an abrasive surface). Do this with as many seeds as you can; they will probably not all sow, and the ones that do will be of varying characteristics. The more seeds you plant, the more chances you will have to get the resulting plant you want. Place your seeds in lukewarm water for 24 hours. Viable seeds will sink to the bottom, and non-viable seeds will float to the top. You can discard any seeds that float.
  4. Water your prepared seed tray or pot filled with soil, and ensure that good drainage is occurring. Place your seeds in your prepared pot or seed tray about a quarter inch to a half-inch under the soil surface. Cover them with soil and water with your spray bottle. Place your tray of seeds in a warm area that receives bright, indirect light. A greenhouse is the most ideal climate, but a planting tray inside a window will do as well. Germination usually takes between 14 and 27 days from sowing. Once you begin to see seedlings sprout and they are able to be handled, transplant them to their own individual 3-inch pots, filled with the same potting medium as described in Step 1. Loosen the seedlings from the potting medium by digging down with the tines of your fork about an inch and a half, gently working the seedling up until it is out. Then, replant the seedling in its individual pot.
  5. Keep the seedling's potting medium moist, but not wet, by spraying the soil with your spray bottle. Keep your new plant in an area with bright light (though not direct sunlight) and temperatures between 55 and 70 degrees Fahrenheit. Ensure that the soil stays moist, but not wet, until the next spring (after the danger of frost has passed), when you can transplant it to its new home.
Cassia seeds are contained inside of the dark pods that dangle from trees.
Cassia seeds are small and brown. There are many seeds contained within each pod.

Problems and Pests

Cassia trees are relatively resilient, though they are susceptible to developing issues with the following pests and diseases:
  • Thrips
  • Aphids
  • Spider Mites
  • Canker
For information on these issues, consult the pages linked below:
​

Gallery

Camellias are great candidates to be grown as container plants on your patio.
Use Cassia trees to adorn walkways in water-wise landscaping.
These statement trees are wonderful for adding shade and color to bland gardens.
Cassia trees will normally form multi-trunked trees, but when young can be pruned, if desired, into a single trunk.
The seed pods on these trees emerge green and mature to brown-black.
Cassia flowers are most commonly yellow to golden in color, but can be pink or white, as well.

Videos

How to prune Cassia trees.
Tips and tricks for growing Golden Shower Tree.
Learn all about these gorgeous garden ornamentals.

Resources

Tips for Planting a Cassia Tree and Its Care
Wikipedia: Cassia
The New Sunset Western Garden Book: The Ultimate Gardening Guide (2012) - Page 224, Cassia leptophylla