Right plant, right place

The Western Australian Botanic Garden is a continually evolving canvas as the team looks to jump on new opportunities and combat challenges facing collections in our changing environment.

With their star-like flowers and delicate fragrance, a must-see in any trip to the botanic garden is the Boronia collection, however a precinct review uncovered the collection was facing new challenges to health and longevity. 

The Kings Park team responded, and a new trial garden bed for the Boronia collection was established in June near the Water Garden. The trial bed replaces a large area of sedge with 190 Boronia plants in an area of low-lying topography. 

The natural water catchment area where the trial bed is situated is cooler and more protected from Perth’s hot easterly winds than the existing Boronia bed. These conditions will ensure consistent moisture for the plants and avoid topsoil drying out as readily due to sun and wind exposure.

Boronias have a reputation for being fickle due to their shallow and dense root systems requiring consistent moisture but being sensitive to waterlogging. An issue that gardeners often come up against when growing Boronias is root rot. 

To avoid waterlogging plants, the right soil mix is key. A sandy or loam soil is generally considered to be the most suitable for Boronias, with a slightly acidic pH between 5.5-6.5. Boronias thrive best with moisture retentive, but well-draining soil.

For home gardeners, cultivating Boronias in pots in free-draining, humus rich soil is recommended, or placing in a semi-shaded, reticulated position in garden beds. Other tips include providing supplementary water over summer to avoid dryness and mulching well to retain moisture. To avoid fungal issues, avoid mulching near the stem, and water at the base of the plant rather than overhead. 

When grown successfully, Boronias are a wonderful addition to gardens with their colourful blooms and aromatic foliage. A number of Boronia species and hybrids also have fragrant flowers, with Boronia megastigma a well-known and popular favourite for this reason. Alongside Boronia megastigma, 11 different Boronia species and hybrids can be spotted in the new trial bed. 

For now, the existing Boronia collection will remain as the team assess the progress of the trial bed over the coming years. It is hoped that not only will the new bed allow for longer lasting and healthier Boronias, but also that BGPA’s knowledge of growing Boronias will develop even further. 

Visit the trial bed next time you are at Kings Park! You can find the new Boronia bed across the pond from the Water Garden Pavilion, on the eastern side of the path.