Your heart will miss a beat, then go aflutter when you take in their intoxicating smell. Next, your heart will break when they curl up and die, leaving a hole in your garden and a searing ache in your memory for that sweet, citrusy, spicy aroma. Boronias are a beautiful Aussie native plant family, featuring small, star-shaped flowering shrubs.
Springtime is when the little brown boronia (B. megastigma) shrub is smothered with tiny, cup-shaped yellow-and-brown flowers, wafting the sweetest of all smells in the season. Or there is the native rose (B. serrulata) or red boronia (B. heterophylla), which produces crowds of pretty pink, red, or white cups with a milder but still profound perfume. Boronias are members of the Rutaceae family, to which citrus also belongs.
KEY TAKEAWAYS
- Keep boronias away from humidity and clay soil — both encourage root and crown rot, which quickly kills the plant.
- Plant in well-drained, slightly acidic soil, in an east or northeast spot with dappled sun and shelter from wind and afternoon heat.
- Water regularly, especially during flowering, and feed lightly with slow-release fertiliser once flowering finishes.
- If your garden isn’t boronia-friendly, grow one in a terracotta pot instead — it’s often the safer bet for this notoriously fussy native.
But like anything that has such exquisite properties, it doesn’t come easy. They can die within months of being planted. Don’t blame yourself, however. This perfection is achieved because of its pernickety nature.
Here’s how you can nurture these beauties to last in your garden for longer.
How to grow boronias
Since boronias can be so tricky to keep alive and thriving, we’ve got all the tips and tricks you need for a happy plant.
Create the right conditions
Boronias hate humidity and soil that retains moisture (clay).
Too much moisture in the air encourages soil-borne fungi that rot the lower stems and crown. There’s little you can do once this begins, and the plant will eventually wilt and die.
Too much moisture in the ground can cause root rot. Boronia roots are relatively shallow and, while they need watering, they don’t need it hanging around their roots as happens in clay soils.
Tips for survival
- Lower the humidity around the bases of your boronia plants by adding a layer of gravel or rocks. This helps keep the roots cool.
- Avoid the pooling of moisture around the roots by putting a layer of pea gravel at the base of the hole before you plant.
- Recent grafted boronias have developed some resilience and are available through specialist native plant nurseries.
How to care for boronias
Climate
Best grown in warmer, coastal areas.
Aspect
East or northeast under dappled sunlight, with protection from winds and afternoon sun.
Soil
Very well-drained, and slightly acidic. Enrich with organic matter, well mixed in the soil but not too close to roots.
Watering
Water regularly; most boronia plants have weak, shallow roots that can dry out in summer. Keep water up when flowering begins, especially if winter has been dry.
Feeding
A small amount of slow-release fertiliser after flowering has finished.
Pruning
Regularly cut flowers to encourage new growth. Trim by about a third after flowering to keep it compact.
How to grow boronias in pots
Boronias are so finicky that you may need to consider them short-lived perennials. An alternative is to grow them in pots.
- Choose a pot that is at least twice the size of your plant, about 30cm.
- Opt for a terracotta pot as excess water seeps through the clay rather than lingering in the soil.
- Don’t use a pot saucer; instead, put the pot on feet so excess water can drain away.
- Use quality potting mix with a couple of handfuls of slow-release native plant food.
- Place in a sheltered courtyard or on a balcony that gets a couple of hours of morning sun each day.
- Water and feed as you would if it is in your garden.
How to care for cut flowers
The best boronia flowers for keeping in a vase indoors and filling your rooms with their wondrous perfume are the brown boronia (B. megastigma) and red boronia (B. heterophylla).
- Cut from the bush when the flowers are starting to open.
- Strip leaves from stems that will sit in water. Put leaves in a shallow dish so that, as they dry out, they release more of their perfume.
- Place in an area free from draughts and out of direct sunlight.
- Change water daily.
- They are sensitive to ethylene, so keep them away from fruit bowls.
