Rainbow Cassia Plant Care

Rainbow Cassia (Senna multijuga subsp. multijuga) belongs to the Fabaceae family within the Senna genus. Rainbow Cassia is also known as Senna.

Rainbow Cassia displays an upright, spreading shrub growth habit, reaching up to 5 ft tall with a spread of approximately 5 ft. Rainbow Cassia produces bright yellow, pea-like flowers in clusters.

Leaf size: approximately 4 inches.

Water a young or newly planted Rainbow Cassia every 7–10 days, soaking the whole root zone, until it is established — usually one to two growing seasons. Established trees mainly need water during long dry spells. In a container, water whenever the top few centimetres of soil are dry.

Rainbow Cassia thrives in full sun to partial shade.

Senna multijuga subsp. multijuga tolerates temperatures of 60–85°F. Rainbow Cassia prefers humidity levels of 40–70%.

Well-draining sandy loam with added organic matter. Good drainage is essential for Rainbow Cassia to prevent waterlogging, which leads to root rot and fungal issues.

Feed Rainbow Cassia every 6 months during the growing season with a balanced, slow-release fertilizer at the rate on the label. Established trees in good soil often need little extra feeding, so let weak growth or pale foliage guide you.

Stop feeding by late summer so new growth can harden before winter.

The PlantoScan app can remind you when to water and when to fertilize each plant.

Choose a spot with full sun to partial shade and well-draining sandy loam with added organic matter. Avoid low spots where water collects after rain.

Rainbow Cassia is suited to USDA Zone 13a.

Plant container-grown or balled-and-burlapped trees in spring or early autumn, setting the root flare at soil level, and water well after planting.

Rainbow Cassia can spread to about 5 ft (1.5 m) and reach about 5 ft (2 m) tall. Space plants about 5 ft (1.5 m) apart so mature crowns don't crowd each other, and plant at least half that distance from buildings, fences and paths.

Planning a row or hedge? Try the tree spacing calculator.

Prune Rainbow Cassia while it is dormant in late winter: first remove dead, damaged and crossing branches, then thin lightly for shape.

If it flowers in spring, prune right after flowering instead so you don't remove next year's buds. Never take off more than about a quarter of the tree in one year.

Rainbow Cassia is frost-tender (hardy to USDA zone 13). In colder areas grow it in a container and move it to a bright, frost-free place before the first frost.

Rainbow Cassia can be propagated through seeds, softwood cuttings. Similar propagation techniques also apply to alexandrian senna plant care, which shares the same genus.

See all plants toxic to cats and plants toxic to dogs.

Rainbow Cassia is susceptible to aphids, caterpillars, spider mites. Inspect the foliage regularly, especially along leaf undersides and stems. Treat infestations promptly with insecticidal soap or neem oil to prevent spread.

Yellow leaves, brown tips or drooping? See common plant problems and how to fix them.

Rainbow Cassia grows outdoors in USDA Zone 13a. It survives winters down to planting zone 13a. In cooler regions, grow Rainbow Cassia as a houseplant or bring it indoors before the first frost.