Cassia Plant Growing & Care Guide for Gardeners

Article by Dean Ravenscroft, Ph.D. - Updated 21st Nov 2023

In this Gardener's HQ guide, we'll explore cultivating Cassia plants in your garden, indoor spaces, and other settings.

At a Glance: Cassia

Plant Characteristics: Cassia is celebrated for its vibrant yellow flowers and attractive, fern-like foliage. It provides a tropical feel and brightens up any landscape with its showy blooms.
Ideal Growing Conditions: Prefers full sun and well-drained soil. It's heat-tolerant and thrives in warm, sunny climates.
General Care: Requires minimal care once established. Water regularly during dry periods and prune as needed to maintain shape.
Tips for New Gardeners: Senna is ideal for beginners due to its low maintenance needs and hardy nature. Just provide adequate sunlight and an occasional watering.

Wild Senna, and Shower Trees: Cultivation & Garden Use

Cassia plants can be either hardy perennial or annuals.

They generally reach an height of 60 cm to 1.2m (2 to 4 feet), and often resemble small perennial trees.

Cassia javanica
Cassia javanica - Pink shower tree by Tatters.

Some Cassia plant common names include Wild Senna, Candle bush (Cassia alata) American Senna, Golden shower tree (Cassia fistula) and Partridge tree.

When in bloom., Cassia carry small pea shaped yellow flowers.

Senna Macranthera
Senna Macranthera by Mauroguanandi.

Commonly Grown Cassia Species Photographs and Plant Identification

Cassia fistula

Cassia fistula
Cassia fistula (Golden Shower Tree / Purging Cassia), photograph by Forest and Kim Starr; CC.

Cassia leptophylla

Cassia leptophylla
Cassia leptophylla (Gold Medallion Tree), photograph by Tracie Hall; CC.

Cassia javanica

Cassia javanica
Cassia javanica (Java Cassia / Pink Shower / Rainbow Shower Tree), photograph by Forest and Kim Starr; CC.

Cassia alata

Cassia alata syn. Senna alata

Cassia alata
Cassia alata (Emperor's candlesticks / Candle bush / Christmas candles), photograph by Forest and Kim Starr; CC.

Cassia angustifolia

Cassia angustifolia syn. Senna alexandrina

Cassia angustifolia
Cassia angustifolia (Senna), picture by Lalithamba; CC.

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Cassia Growing and Care Guide

Common Names: Senna, Pink Cassia, Desert Cassia, Golden Shower Tree, Pink Shower tree, Sicklepod, Wild Senna, Kassod Tree, Appleblossom Shower, Sensitive Pea, Partridge pea.
Life Cycle: Hardy annual. Hardy perennial.
Height: Garden species: 24 to 300 inches (60 to 750 cm).
Native: Mainly to tropical regions, though some species are native to temperate areas.
Growing Region: Zones 6 to 11.
Flowers: Mainly summer. Some species flower in autumn/winter.
Flower Details: Yellow, pink, orange-red. Senna: Pea-like.
Foliage: Green. Compound leaves. May be evergreen.
Growing Cassia
Sow Outdoors: 1/8 inch (3mm). Summer or autumn. Spacing: Small species: 24 to 36 inches (60 to 90cm); large species (trees) 25 to 30 feet (7.5 to 9 metres).
Sow Indoors: Chip seeds. Soak in water for three hours. Germination time: one week to three months. Temperature 70 to 75°F (21 to 24°C). Seven or eight weeks before transplanting outdoors; either following the last frost or in autumn.
Requirements: Full sunlight or light shade. Good drainage. Regular watering. Regular feed. Thin plants in the autumn. Taking cuttings in spring. Divide in spring.
Family: Leguminosae.
Miscellaneous: Many species are now included within the Senna and Charmaecrista genera; classification of species into these genera is still ongoing. Synonymous with Carthartocarpus.
Do not confuse the genus name Cassia with one of the common names for Cinnamon: Cassia - this is a member of the genus Cinnamomum.

How to Grow Wild Senna - Cassia

If planning to grow a Cassia plant outdoors from the off, it is best to sow out the seed in either Summer or autumn. Do so at a depth of 3 mm (1/8th inch).

Wild Senna-like species should be grown in soil that has good drainage. Ideally locate in either a sunny or partly shaded part of the garden.

When growing Cassia seedlings indoors first, then you will first need to chip the seeds. Following chipping,soak them in warm water for three hours before sowing.

They should be planted about 7 weeks before you transplant the seedlings outdoors. Which should be done in the autumn, or after the last frost of the spring.

When putting the seedlings out, they should be spaced at about 60 to 90 cm apart (24 to 36 inches).

Caring for Cassia

Once established Cassia requires regular fertilisation and watering. Ideally they should be thinned in the autumn.

Common Questions

How many members does the Cassia genus have?

The Cassia genus consists of around 30 to 40 species.

Do members of Cassia make a good garden or landscaping plant?

Indeed, Cassia species, like the Senna or Shower trees, are appreciated for their stunning, yellow blooms and can add a tropical touch to gardens.

Which Cassia species are most frequently grown by gardeners?

Commonly grown species include Cassia fistula (Golden Shower Tree) and Cassia corymbosa (Butterfly Bush).

Are members of the Cassia plant genus fragrant?

Yes, certain species of Cassia, like the Cassia fistula, are known for their sweet fragrance.

What is the perfect location to grow Cassia?

Cassia prefers full sun and well-drained soil. It is tolerant of heat and drought, making it ideal for warm climates.

Is Cassia invasive in the USA?

Some Cassia species, like Cassia fistula, can be invasive in certain states like Florida.

How do I remove Cassia plants from my garden?

Remove Cassia by cutting them back and digging up the roots. Be sure to dispose of the plants properly to prevent re-seeding.

Summary

The Cassia genus belongs to the Fabaceae family and is native to tropical regions. These evergreen trees or shrubs are admired for their bright, yellow flowers that bloom in clusters, often attracting butterflies and bees.

Cassia thrive in full sun, in well-drained soil. They can be grown from seeds or cuttings planted in the spring. Regular watering is needed, but they are relatively drought-tolerant once established. Pruning after the flowering season encourages new growth and a denser form.

I hope that you enjoyed this guide on how to grow Cassia plants. You may also enjoy the following Gardener's HQ growing guides: How to grow Mimosa pudica, Grow Carrots, Sprouting Mung Beans, and Cercis canadensis plants.

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