How to grow boronias: the right variety for your climate zone
The boronia genus belongs to the Rutaceae family. This is the same family as citrus which is why all species produce the characteristic oil gland dots that release a fragrance when crushed.
Pinnate boronia (Boronia pinnata) in flower — the massed pink four-petalled flowers and aromatic pinnate foliage are typical of the genus.
There are species that can be demanding and will not survive outside their specific conditions. But with around 150 species distributed across almost every region of Australia, the boronia genus offers something for nearly every gardener outside the tropics.
Brown boronia (Boronia megastigma) — the brown-and-yellow flowers are the exception in a mostly pink genus, and the source of the most valued fragrance of any Australian native.
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What every boronia needs
All boronias share four non-negotiable requirements.
- Drainage is the most important: more boronias are killed by waterlogging than any other cause. Plant into free-draining, sandy or gravelly soil.
- Phosphorus sensitivity: use only a low-phosphorus native fertiliser as standard fertilisers will damage the root system.
- Annual pruning: prune by one third with sharp secateurs immediately after flowering every year without exception.
- Root disturbance: boronias resent root disturbance more than most natives. Plant from a container directly into the final position without disturbing the root ball.
One further note: most boronias live five to ten years in cultivation. Plan for replacement or propagate from cuttings before the parent plant declines.
Subtropical gardens (SE QLD, northern NSW coast)
Warm, humid summers are the primary challenge for boronias in subtropical gardens. The combination of heat and high humidity through the growing season favours fungal disease, so the choice of species here is narrow and positioning matters more than in any other zone: part shade, excellent air circulation and free-draining elevated ground.
Narrow-leaf boronia (Boronia anemonifolia) — one of the finer-foliaged eastern species, showing the small four-petalled flowers common across the genus.
Pinnate boronia (Boronia pinnata)
Pinnate boronia is the most adaptable of the eastern boronias for warmer conditions, growing naturally from the coastal ranges of NSW into the subtropical margins of QLD. The feathery pinnate leaves are deeply aromatic. Position it on a sheltered slope or elevated bed where air movement prevents the humid stagnation that encourages root rot.
Pinnate boronia (Boronia pinnata) — the most adaptable eastern boronia for warm, humid subtropical conditions, given drainage and air movement.
Moonlight0551 from Australia, CC BY 2.0, via Wikimedia Commons
Growing notes
Morning shade with some afternoon light is preferable to warm humid morning sun. Prune by one third immediately after flowering. Water consistently through establishment then reduce, as wet-dry cycling is more damaging than consistent slight dryness. Apply a low-phosphorus native fertiliser in early autumn.
Soft boronia (Boronia mollis)
Soft boronia is named for the fine hairs that cover its stems and leaves, giving it a soft, tactile quality. It is among the more humidity-tolerant of the genus, growing naturally in the humid coastal ranges and wet sclerophyll of NSW and southern QLD. It is not common in mainstream nurseries but is available from specialist native growers.
Soft boronia (Boronia mollis) — among the more humidity-tolerant species, its stems and leaves covered in the fine hairs that give it its name.
Poyt448 Peter Woodard, CC BY-SA 3.0, via Wikimedia Commons
Growing notes
Plant in part shade in free-draining, humus-rich, acidic soil. It suits the sheltered side of larger shrubs or under established trees where the canopy moderates temperature extremes. Keep the root zone consistently moist but never wet.
Temperate eastern gardens (Sydney basin, Melbourne, ACT, NSW and VIC ranges)
The temperate eastern zone is the richest for garden boronias outside WA. The Sydney basin in particular holds several of the most spectacular eastern boronias in their natural sandstone and heath habitats. The key variables here are soil type, sandstone heath versus heavier clay-influenced soils, and summer humidity on the coast versus drier conditions inland.
Swamp boronia is a delicate shrub with soft pink flowers that grows in the montane swamps and damp heath of the NSW tablelands and southern highlands. Its blooms are subtle but distinct.
Geoff Derrin, CC BY-SA 4.0, via Wikimedia Commons
Ledum boronia (Boronia ledifolia)
Ledum boronia is the best starting point for gardeners new to the genus. It produces deep pink to magenta flowers in such numbers in late winter and spring. Growing naturally across heath and dry sclerophyll in NSW and VIC, it tolerates a wider range of soils and drier summers than most species.
Ledum boronia (Boronia ledifolia) — the most forgiving eastern species and the best starting point for a first boronia, smothered in deep pink flowers in late winter.
Growing notes
Plant in full sun to part shade in free-draining, slightly acidic soil. It tolerates drier summer conditions once established and is one of the most reliable boronias for Sydney gardens on sandy or well-drained soils. Apply a low-phosphorus native fertiliser in early autumn.
Forest boronia (Boronia muelleri)
Forest boronia is arguably the most adaptable boronia in cultivation, suiting both temperate eastern and cool temperate gardens. The soft pink flowers appear prolifically from late winter through spring. It grows at forest margins and in moist sclerophyll across NSW, VIC and TAS, occupying a shadier, more sheltered niche.
Forest boronia (Boronia muelleri) — the most adaptable boronia in cultivation, its delicate soft pink flowers suited to shadier, sheltered positions.
Melburnian, CC BY 3.0, via Wikimedia Commons
Growing notes
Plant in part shade in free-draining, slightly acidic, humus-rich soil. It suits positions under established trees or on the sheltered side of larger shrubs. Water consistently through the first two summers. Ollas buried beside the root zone maintain consistent moisture without overwatering.
Pale pink boronia (Boronia floribunda)
Pale pink boronia is one of the most free-flowering of the eastern species. It grows in coastal heath and dry sclerophyll across NSW, tolerating the combination of salt air, sandy soil and moderate humidity better than most species. Less commonly grown than ledum boronia, it is worth seeking out for coastal gardens.
Pale pink boronia (Boronia floribunda) — one of the most free-flowering eastern species, well-suited to coastal gardens on sandy soil.
P. Ollerenshaw, CC BY 3.0 AU, via Wikimedia Commons
Growing notes
Plant in full sun to part shade in free-draining, sandy, acidic soil. It is better suited to coastal positions than most eastern boronias. Prune by one third after flowering. Keep standard fertilisers away from the root zone.
Native rose (Boronia serrulata)
Native rose is the most coveted of the eastern boronias, with deep rose-pink flowers on a compact shrub that is beautiful in flower. It is also the most demanding, restricted in nature to the nutrient-poor, sharply-draining sandstone soils of the Sydney basin.
Native rose (Boronia serrulata) — the most coveted eastern boronia, restricted in the wild to the sandstone soils of the Sydney basin and demanding in cultivation.
Growing notes
Sandy, sharply-draining, acidic sandstone soil in part shade. Resents any improvement to the soil, any phosphorus, any disturbance to the root zone and any inconsistency in moisture.
Cool temperate gardens (VIC highlands, TAS, ACT, southern SA ranges)
Cool temperate gardens suit several boronia species well, as cold winters, mild summers and reliable rainfall mirror the conditions in which many species evolved. Most temperate boronias tolerate moderate frost.
A boronia in full flower — the massed pink display that makes the genus so valued in the cooler-climate garden.
Hairy boronia (Boronia pilosa)
Hairy boronia is one of the more frost-tolerant species in the genus, growing naturally across the cool temperate heath and dry sclerophyll of TAS, VIC, SA and NSW at elevations where winter frosts are regular. Less spectacular than some species, its compact size makes it useful at the front of a border or in a pot where drainage can be controlled.
Hairy boronia (Boronia pilosa) — one of the more frost-tolerant species, compact enough for the front of a border or a well-drained pot.
Russell Best, CC BY 3.0 AU, via Wikimedia Commons
Growing notes
Plant in full sun to part shade in free-draining, slightly acidic soil. It tolerates moderate to heavy frost and suits the cool temperate gardens of TAS and the Victorian highlands well. Prune by one third after flowering. Apply a low-phosphorus native fertiliser in early autumn.
Lemon-scented boronia (Boronia citriodora)
Lemon-scented boronia offers a different fragrance to the rest of the genus. Where most boronias are scented from the flowers, this one's primary fragrance comes from the foliage. It grows in cool temperate forest and sclerophyll across VIC, NSW and TAS and is among the more cold-tolerant species in the genus.
Lemon-scented boronia (Boronia citriodora) — grown for its foliage rather than its modest flowers, releasing an intense clean lemon scent when the leaves are brushed.
Murray Fagg, CC BY 3.0 AU, via Wikimedia Commons
Growing notes
Plant in part shade in free-draining, humus-rich, acidic soil. It suits sheltered positions under established trees. Water consistently through the first two summers. Keep phosphorus fertilisers away from the root zone.
The wildlife value of boronias
The nectar and pollen of the massed flowers of boronias support pollinating and beneficial insects, with some benefit to smaller nectar-feeding birds.
The massed four-petalled flowers of a boronia in full bloom offer accessible nectar and pollen to native bees and other beneficial insects.
| Benefit | What boronias provide |
|---|---|
| Native bees | The massed four-petalled flowers offer accessible nectar and pollen through late winter and spring, a period when few other shrubs are flowering. Generalist native bees are the primary visitors. |
| Butterflies and hoverflies | The open flower structure suits butterflies and hoverflies. Hoverflies are doubly valuable, as their larvae prey on aphids and other soft-bodied garden pests. |
| Beneficial predatory insects | The nectar draws in parasitoid wasps and other beneficial insects whose larvae control pest populations, contributing to natural pest balance in a mixed planting. |
| Small nectar-feeding birds | Some smaller honeyeaters and other nectar-feeders will visit the flowers, though boronias are a supplementary rather than a primary bird-nectar source. |
| Winter and spring forage timing | The late-winter-to-spring flowering fills a seasonal gap, providing forage when many other nectar sources have finished and pollinators most need it. |
| What they do not provide | Boronias offer little in the way of seed for birds, dense nesting habitat or the heavy bird-nectar volumes of banksia and grevillea. Pair them with those genera for a fuller wildlife garden. |
Mediterranean WA gardens (Perth, southwest WA coast and ranges)
The southwest WA Mediterranean-climate zone contains the highest concentration of boronia species in the world: around 100 of the 150 known species are endemic to this region. Gardeners in Perth and the southwest are spoiled for choice.
Winged boronia (Boronia alata) — one of the many pink-flowered species endemic to the southwest WA botanical hotspot.
Brown boronia (Boronia megastigma)
The flowers of brown boronia are unusual: brown and green outside, yellow inside, a combination that looks like a botanical curiosity until you understand the extraordinary fragrance is the point. The scent is most intense in cool morning air and carries far further than the modest flower size suggests. It grows in the jarrah forest and heath of southwestern WA in sheltered, partly-shaded positions in free-draining, slightly acidic soil.
Brown boronia (Boronia megastigma) — grown commercially for perfumery and performing well as a container plant where drainage and moisture can be managed.
Growing notes
Plant in part shade in free-draining, slightly acidic soil, as it dislikes both full sun and heavy soils. It performs well as a container plant where drainage and moisture can be carefully managed. Apply a low-phosphorus native fertiliser in early autumn only.
Red boronia (Boronia heterophylla)
Red boronia produces deep magenta-pink flowers of such intensity that the common name undersells them, closer to saturated cerise than red. It is one of the most spectacular boronias in the genus and one of the most intensely fragrant of all Australian plants, the scent used commercially in perfumery. For full coverage of red boronia, see the pink flowers guide.
Red boronia (Boronia heterophylla) — the deep magenta-cerise flowers are among the most intensely fragrant of any Australian native.
Growing notes
Part shade, free-draining slightly acidic soil, consistent moisture, annual pruning by one third after flowering. Dislikes hot dry conditions and summer heat without shelter. One of the most rewarding boronias for Perth gardens in the right position.
Further WA species
The diversity available to WA gardeners makes several more species worth noting. Boronia crenulata (shark bay boronia) is compact at 0.5–1m, flowers vivid pink through winter and spring and is more drought-tolerant than most WA species. Boronia cymosa (clustered boronia) produces dense clusters of deep pink flowers in spring on a similarly compact form and is one of the most reliable and garden-adaptable WA boronias. Boronia denticulata (maidenhair boronia) is the most visually unusual, its fine, maidenhair fern-like foliage as ornamental as its pink flowers.
Shark bay boronia (Boronia crenulata) — compact and more drought-tolerant than most WA species, useful in drier Perth gardens.
Why are most boronias pink?
The pink through magenta that dominates the genus comes from anthocyanins, the same pigment group behind most pink, red, purple and blue flowers worldwide. Boronia's main pollinators are native bees, whose colour vision runs from green through blue into ultraviolet, and pink and magenta sit well within the range they see and are drawn to.
The exceptions are the interesting part. The lavender-blue of blue boronia is still an anthocyanin, shifted along the same pigment pathway. Brown boronia breaks the pattern entirely with brown-and-yellow flowers and leads with scent rather than colour, and several boronias are now known to be pollinated by tiny fragrance-drawn moths rather than bees. So while colour explains most of the genus, fragrance carries the species where colour does not.
SA and dry temperate gardens (Adelaide, Eyre Peninsula, SE SA, inland VIC)
SA gardens sit in a transitional zone where some WA species perform well in the Mediterranean-climate areas around Adelaide and the southern coast, while cooler areas suit the temperate eastern species that extend into SA naturally. The drier summers of inland SA are more challenging, and species selection should lean toward the strongest drought tolerance once established.
Blue boronia (Boronia coerulescens)
Blue boronia produces a soft lavender-blue that is genuinely unusual and immediately identifiable. It grows in the mallee scrub and coastal heath of southwestern WA and extends into SA, occurring on Kangaroo Island and parts of the Eyre Peninsula. Compact at 0.3–1m and more drought-tolerant than most WA boronias, it is the more practical choice for drier SA gardens than the moisture-demanding species from the wetter WA southwest. It is available from specialist WA native growers.
Blue boronia (Boronia coerulescens) — one of the few boronias in a blue-mauve rather than pink, and more drought-tolerant than most WA species.
Maree Goods, CC BY 2.5 AU, via Wikimedia Commons
Growing notes
Plant in full sun to part shade in free-draining, sandy or gravelly, slightly acidic soil. It is more tolerant of dry summer conditions than most boronias and suits Mediterranean-climate gardens in SA and the drier parts of the WA southwest.
Arid and tropical gardens (inland NSW, QLD, NT, WA; tropical north)
There are no garden-appropriate boronia species for genuinely arid, semi-arid or tropical conditions. Attempting to grow boronia in these climates may not succeed.
For dry and arid gardens, the flowering shrubs that fill a similar role are eremophilas, swainsona (darling peas) and ptilotus species, all genuinely adapted to low rainfall and offering comparable interest in the flowering shrub layer. For tropical gardens, the genus has no representatives, and gardeners there are better served by the extraordinary range of tropical native flowering plants available.
Choosing the right boronia
The boronia genus rewards specificity. The match between species and conditions is everything.
Boronia 'Moonglow' (Boronia heterophylla) — a garden selection showing the softer pastel end of the genus's colour range.
The three things that matter most, regardless of species or zone, are drainage above all else, annual pruning without exception, and realistic expectations about lifespan.
For more on growing other iconic Australian native genera, see the guides to grevillea, banksia, hakea, kangaroo paw, waratah and wattle.
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