Boronia

( bo - ROH - nee - uh )

At-A-Glance Information

Boronia, sometimes called Scent Leaf, is a genus of evergreen shrubs that needs full sun to light shade and regular waterings for best performance. They produce clouds of pink, white, or mauve fragrant flowers against wispy-looking foliage. These shrubs are native to Australia. Care must be taken when planting these shrubs around your yard, as the leaves can sometimes cause dermatitis. 

Boronia Species and Varietals

The genus Boronia includes around 160 species and is included in the family Rutaceae. It is named for Francesco Borone (1769 - 1794), an Italian naturalist and plant collector. It was first described by James Edward Smith in the publication Tracts Relating to Natural History. Boronia growing zones vary by species. For more information, see the species descriptions below. To find your zone, click here: Zone Map.

Boronia 'Carousel'
Zones 15-17, and 19-24, upright grower to 4-6 feet tall. Leaves are aromatic and in late spring, the plant is covered with pink flowers that age to red.

Boronia clavata (Heather Wand)
This variety grows best in zones 15-17 and 19-24. This shrub can get to 4-6 feet tall and wide. Leaves are light green and aromatic, flowers are greenish yellow and lightly scented. Grows best in partial shade, and can be used as a screening plant.

​Boronia crenulata
Zones 16-24; 2-3 feet tall and 3-4 feet wide. Leaves are small and dark green, and flowers are small and light pink and appear in late winter and spring. Varieties include 'Rosy Splendor' (a more upright grower), 'Shark Bay' (compact with licorice-scented leaves and pink flowers that appear year-round).

​Boronia denticulata
This species grows best in zones 15-17, and 20-24. Grows to be 3-8 feet tall and 1.5-4 feet wide. Leaves are strongly aromatic and can cause dermatitis if touched. Flowers are mauve and pink, and at times white on some varieties. They bloom in late winter and spring, and sporadically throughout the rest of the year.

​Boronia heterophylla (Red Boronia)
Grows in zones 16-24, and has a dense growing habit to 6-8 feet tall and 4-6 feet wide. Leaves are finely cut and blooms are profuse in deep pink with reddish buds. Bloom time is late winter and spring. Intensely fragrant plant.

Boronia megastigma (Brown Boronia)
Grows best in zones 15-17 and 20-24, this is a more compact variety growing to about 2 feet tall and wide with bell-shaped deep red to brown flowers with yellow interiors. Blooms in the wintertime. This plant has a powerful fragrance. Plant will need replacing every two or three years. 'Jack McGuire's Red' has deep red to orange blooms.

Caring for and pruning Boronia shrubs

Boronia shrubs prefer light, well-draining soil that is slightly acidic. The roots should never be allowed to become completely dry or stay wet for too long (they can be susceptible to Root Rot under moist soil conditions). Mulch around the bottom of the plant after placing it in the ground to protect the roots and increase humidity. A light pruning can be completed after blooms fade to encourage a more bushy, less leggy habit and to rejuvenate the plant and promote more new foliage growth. Apply a slow-release balanced fertilizer once a year after flowering has finished for the season.

Propagation

Boronia plants can be propagated either through cutting or through seed. Cutting is the preferred method, however, given how difficult it is to both collect and germinate Boronia seeds. To propagate Boronia by cutting, follow these instructions:

Propagating Boronia 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 potting soil.
  2. In spring or summer (May to August), before the plant has had time to harden its current season's growth, choose your 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 4-6 inch portion(s) of the end of a non-blooming branch and strip off all of the lower leaves, leaving the top two on the cutting. 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.
  3. Moisten with water, and ensure that the pot has good drainage. Your pot should be kept in cool, sunny conditions indoors (and not in direct sunlight). Water whenever your soil is dry under the top layer. After about two months have passed, your cutting should be rooting. When you notice new growth on your propagated Boronia, 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, for about 18 months, after which your new Boronia will be ready to be planted in its new home in your garden.

Problems and Pests

Boronia shrubs are affected by the following pests and issues:
  • ​Root Rot

Gallery

Boronia flowers make great additions to cut flower arrangements.
Boronia shrubs can add a native look to gardens.
Plant Boronia amongst other shrubs in areas of the garden that receive good drainage, such as on slopes or hills.

Videos

All about Boronia shrubs.
How to grow and care for Brown Boronia.

Resources

Wikipedia: Boronia
How to Grow and Care for Boronias
Boronia Information and Plant Care
Cultivation and Propagation of Boronia and Its Relatives
The New Sunset Western Garden Book: The Ultimate Gardening Guide (2012) - Page 200, Boronia
If you have any questions, comments, concerns, or photos you’d like to add to the gallery, please let me know by sending me a message using the button below!
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