An erect, multi-branched shrub, growing to 2 metres.
It occurs naturally only in the Greater Sydney Basin, growing from the west in the Blue Mountains near Faulconbridge, to just north of Gosford (with an outlying record further west in Wollemi National Park), south through Sydney to Camden-Picton area (with another outlying record near Berrima).
It is typically found in wet sclerophyll forest and rainforest in gullies on Narrabeen Sandstones.
The branchlets are hairless to sparsely stellate-hairy, prominently 4-angled (rhomboidal in cross-section).
Boronia spp. produce opposite leaves which can be simple or compound (sometimes on the same plant) and are usually aromatic (sometimes strongly-so).
In this species, leaves are compound-pinnate, with 3 to 7 leaflets in distant pairs with one terminal leaflet, with overall leaf length to 125 mm long and to 100 mm wide; leaflets are elliptic to obovate, to 60 mm long and 15 mm wide.
Boronia have complete flowers (bisexual and with all whorls present). The flowers are produced either solitarily or in groups, in the leaf axils, or, at the branch terminals. There are usually four sepals, four petals and generally eight stamens, surrounding one female part (carpel). Flowers are often pink to purple, which makes them easily identifiable in NSW bushland.
In this species, flowers are produced in groups of 2 to 6 or more bright to pale pink flowers each about 15 mm in diameter, well displayed in clusters from the upper leaf axils. Flowering occurs from July to October.
The fruit of Boronia are described as a schizocarp-capsule; a capsule that splits into even segments, which each segment called a coccus.
The fruit are 4 to 5 mm long and 2.5 to 3 mm wide.
This is a very attractive species which has been in cultivation for many years. It has a history for being difficult to maintain and is much less reliable compared to B. mollis. The hybrid ‘Telopea Valley Star’ is a cross between B. mollis and B. fraseri and is considered to be a much more reliable as a garden subject.
B. fraseri requires a well-drained moist soil, preferably in semi-shade, and it is tolerant of at least moderate frost.
Growing boronias can be a frustrating experience and they have a reputation for being difficult. Their attractiveness has led to substantial efforts to cultivate them. One tip is to try to grow forms that are local to your area, rather than attempting to grow those species from interstate. There are certainly some species that have proven easier to grow than others.
Most Boronias have a short life span of two to three years in a garden situation but are a rewarding plant while healthy as they provide lovely fragrance and flowers in Spring.
For them to grow at their best, select a position with dappled sunlight and especially protection from hot afternoon sun in summer, as well as from wind, which they dislike.
The soil must be well drained and have an even supply of moisture. If they dry out, they will surely die.
Planting on a slight slope is said to work well.
For a longer life, the best way to grow them is in a medium sized pot, say 30 cm in diameter where drainage and moisture can be controlled. A sheltered patio or courtyard that receives at least a few hours sunlight a day would be ideal
Fertilise after flowering.
The conventional wisdom is, think deeply about which species to plant and the location to plant it.
In common with most members of the Rutaceae, propagation of B. fraseri from seed is difficult. In addition, cuttings of B. fraseri seem to be more difficult to strike than some other members of the genus.
Boronia is a genus of about 150 species in the citrus family Rutaceae. Most species are endemic to Australia and species can be found in all states. There are also 4 species in New Caledonia, which were previously placed in the genus Boronella. In 2020, several species of Boronia have been transferred to the genus Cyanothamnus (meaning “blue shrub or bush”), as these species have been found to be more closely related to other Rutaceae genera rather than other Boronia species. After the move of some species to Cyanothamnus, there are about 30 Boronia spp. in NSW.
Boronias are likely to be killed by fire and regenerate from the seed bank.
Boronia – after Francesco Borone (1769-1794), an 18th century Italian botanist who assisted John Sibthorpe. Allegedly, he died at age 25, due to falling out a window whilst collecting plant specimens.
fraseri – after Charles Fraser (1788-1831), Colonial Botanist of New South Wales from 1821 to 1831. During that time, he was instrumental in the development of Sydney Botanic Gardens, receiving and sending plants and seeds to all the major horticultural centres as well as to penal settlements and major gardens in New South Wales. He collected and catalogued hundreds of Australian plants and more than thirty plant species are now named after him.
This species is not considered to be at risk of extinction in the wild.
Australian Native Plants Society Australia – Boronia Family Profile Page
Gardening with Angus Website – Boronia for Beginners
Wrigley, J.W. & Fagg, M.I. (2001). Australian Native Plants – Propagation, cultivation and use in landscaping. 4th edition. New Holland Publishers, Pty. Ltd. Australia.
NSW Flora Online (PlantNET) – Boronia fraseri Profile Page