March 29, 2016

Cassias are native to the warm regions of Australia and Africa. Many of the Australian and North American species previously called Cassia have been reclassified to the genus Senna. However, these plants are still widely sold in our local plant nurseries under the scientific name of Cassia. Most cassias have fine textures foliage and bloom from late winter through spring. Most are evergreen, but those that bloom during the summer tend to be deciduous. While cassias have many uses in the landscape, they are most widely used for screening, and can reach a mature height and width of six to eight feet. They have varying degrees of cold hardiness, and require full sun.

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This feathery cassia has a nice natural shape and does not require shearing.

Cassias tolerate heavier soils if given infrequent, deep watering, but prefer soils that drain rapidly. Cassias are extremely drought tolerant and require little or no supplemental fertilization or irrigation. Their abundant color display is followed by a prolific crop of seed pods. Cassias’ natural round form reduces the need for severe pruning, but you may prune lightly after flowering to minimize the production of seed pods. As with most flowering plants, their yellow flowers attract bees. Plan your landscape carefully, keeping in mind the ultimate size of the species.

Cassia artemisioides, Feathery Cassia (also sold as Senna artemisiodes, Feathery Senna)
Feathery cassia’s fine, gray, needle-like foliage provides a great backdrop for its fragrant yellow flowers. It contrasts well with other colors and textures in the landscape. Feathery cassia is especially suited for mass plantings, informal screens, and natural desert or wild gardens that require little or no maintenance. Feathery cassia is a native of Australia. It requires full sun and the flowers can be damaged during late winter frosts.

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Desert Cassia is darker green but has very similar foliage to Feathery Cassia.

Cassia nemophila, Desert Cassia (also sold as Senna nemophila or Senna artemisiodes v. filifolia, Green Feathery Senna)
Desert cassia has deep green, needle-like foliage, providing a lush alternative in the desert landscape. When used as a background plant, its dark green color accents plants with gray or silver foliage. Desert cassia makes a nice screen barrier and shows extremely well in mass plantings. It can be used in arid or transitional plantings to add color. This Australian cassia is more cold-hardy than feathery or silver-leaf cassias.

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The Silver-Leaf Cassia has leaves that are flat and wider than the other Cassias.

Cassia phyllodenia, Silver-leaf Cassia (also sold as Senna phyllodenia or Senna artemisiodes v. petiolaris, Silver-leaf Senna)
Silver-leaf cassia lives up to its name because of the rich silver color of the foliage. The leaves are flat and sickle-shaped. Silver-leaf cassia provides a ripple effect in the wind, thereby creating a living sculpture in the landscape. Its golden yellow flowers bloom in the winter and early spring. As with other silver or gray leaf plants, it needs full sun. This cassia is also a native of Australia.

Did you know that up to 70% of water use is outdoors? That’s why we love desert plants and feature them each month. It’s still a great time to plant, and you can learn more about Cassias and other plants on our Arizona Low-Water-Use Plants page. Visit our page on Choosing and Planting Low Water-Use Plants for tips on plant selection and how to plant properly.

This feature is based on a concept and text originally developed jointly by the Arizona Nursery Association and the Arizona Municipal Water Users Association (AMWUA) with partial funding from the Arizona Department of Water Resources. Learn more about these and other great desert plants at the Arizona Municipal Water Users Association Landscape Plants for the Arizona Desert plant database or see our previously featured Plant of the Month blogs. All photos in this blog were taken and submitted by Steve Priebe.