If a Big Mac can taste like happiness then the Brown Boronia is the smell of happiness. There are very few plants that can give off the tantalizing scent that the Boronia does. It should be said, however, that Boronias do not rank among the easiest of plants in the garden but it is fair to say that with the right attention you can enjoy delightful displays of this outstanding shrub. If you treat Boronias as short-lived perennial shrubs in your garden then you can enjoy them while they last without being overly disappointed if they do not become a more permanent part of the landscape.
It is very important to try and provide boronias with the optimum growing environment in order for them to fulfil their full potential. Dappled sunlight is ideal and especially protection from hot afternoon sun in summer, as well as from wind, which they dislike. A well drained soil is essential in order to lessen the chances of the plant succumbing to its greatest enemy, root rot. Lowering the humidity around the base of the plant by mulching with a layer of gravel also seems to help discourage the fungal pathogens that cause the roots and crown of plants to rot. Additional moisture may be required by boronias when they are coming into bud and bloom, particularly if dry weather prevails through late winter.
Longer stems can be used for cut flowers when the first few buds have started to open. This will also serve to start the pruning process which can be completed after flowering by giving the plant a light trim to remove any dead flowers that remain. This is also the perfect time to fertilise the plant by giving it a handful of a slow release native plant food or alternatively mulch around the base of the plant with a layer of well-rotted horse or cow manure a few cm thick. I have had people ask me if they should feed their boronia when it is in bud, the answer is to wait until after your boronia has flowered before you fertilise. If you feed before blooming you risk stimulating ‘bypass’ growth, where leafy new growth starts and covers up the flowers before they have a chance to bloom. As soon as flowering has finished, cut back just behind the spent flowers and then fertilise to stimulate the new vegetative growth that will create next year’s flower display.