The Boronia Family - Cultivation

Like most groups of plants, some members of the "Boronia Group" have proved to be easy to grow in cultivation over a wide range of climates, others grow well in some districts and not in others while others have proved to be a cause of frustration, generally. The genus Boronia, itself, is the source of much of the frustration because of the many attractive species it contains which have not adapted well to cultivation.

As a general rule, members of the group require the following combination of conditions:

  • Excellent drainage - they will not tolerate waterlogging
  • Assured moisture - but freely draining
  • Protection from direct summer sun - dappled shade is ideal
  • Good light - not dense shade
  • Light soils (eg sandy loams)
  • Suitable climate

The last item is probably the most difficult to accommodate. Generally, it is pointless trying to grow species native to Mediterranean climates (dry summer/wet winter) in tropical and sub tropical areas. This means that plants such as the brown boronia (B.megastigma), which is renowned for its beautiful perfume, are not long term propositions in humid climates. They can, however, be grown for 1 or 2 seasons as small pot plants and then replaced.

There are always exceptions to any general rule and B.denticulata, a western Australian species is reasonably hardy in humid areas.

A number of horticultural forms have been brought into cultivation, particularly in Boronia, Correa, Crowea and Philotheca. These have generally resulted from collections of unusual forms from the wild or from chance hybridisation between garden-grown plants. There has been little or no deliberate hybridization in this group of plants. Table 4 lists some of the more reliable or readily available species and cultivars but the list is not meant to be comprehensive and availability will vary from district to district.


Table 4 - The Boronia Group; 20 of the Best!

Plant Common
Name
Size
HxW (m)
Flower
Colour
Comments
Asterolasia hexapetala None
1.5 x 1.5
White Very attractive shrub with large flowers; not commonly cultivated.
Boronia denticulata None
1.0 x 1.0
Pale pink Attractive and easily grown in many areas.
Boronia megastigma Brown boronia
0.5 x 0.5
Brown and yellow Magnificent perfume; difficult to grow in humid area. Several cultivars available; eg "Chandleri" (burgundy), "Harlequin" (striped red/yellow). "Lutea" (yellow)
Boronia mollis Soft boronia
1.0 x 1.0
Deep pink The cultivar "Lorne Pride" is particularly good.
Boronia pinnata Pinnate boronia
1.0 x 1.0
Mid pink Large flowers and attractive foliage; can be difficult to establish. White form exists.
Chorilaena quercifolia None
1.5 x 1.5
Green or red Attractive, bushy shrub with "oak" shaped foliage; very unusual flowers in which the stamens are prominent.
Correa baeuerlenii Chef's cap correa
1.0 x 1.0
Yellow Rare in nature but easily cultivated in many areas. Attractive glossy foliage and flowers with and unusually shaped calyx.
Correa "Dusky Bells" None
0.5 x 1.0
Red One of the most reliable and attractive.
Correa reflexa Native fuchsia
0.5-1.5 x 1.0
Red/yellow Widespread in nature and very variable; can be difficult to establish and maintain. Selection of local forms is advisable where possible.
Crowea exalata Small crowea
0.8 x 1.0
Deep pink Very attractive bush which can be a little difficult to establish. A white form is in cultivation.
Crowea "Poorinda Ecstasy" None
1.0 x 1.0
Mid pink The best Crowea for the garden; hardy and reliable in many areas.
Diplolaena microcephala Lesser diplolaena
1.0 x 1.0
Orange Best in drier climates; flowers similar to Chorilaena.
Eriostemon australasius Pink wax flower
1.0 x 1.0
Pale to mid pink Very spectacular but difficult to propagate and to establish in the garden; worth the effort!
Leionema dentatum None
2.5 x 2.0
Creamy yellow Beautiful shrub for well drained positions; formerly Phebalium dentatum.
Phebalium glandulosum Desert phebalium
1.0 x 1.0
Yellow Spectacular small shrub; requires excellent drainage and sunny position.
Phebalium squamulosum Forest phebalium
1.0-2.0 x 1.0-2.0
Cream to yellow Variable plant with several forms in cultivation. Most forms attractive and reliable.
Philotheca myoporoides Long leaf wax flower
2.0 x 2.0
White Formerly Eriostemon myoporoides. The commonly cultivated form is a very hardy shrub with an excellent spring display of flowers.
Philotheca nodiflora None
0.5 x 0.5
Mauve Formerly Eriostemon nodiflorus. Colourful small shrub for non-humid climates.
Zieria prostrata None
0.1 x 1.0
Pale pink Rare in nature; available as "Carpet Star". Good groundcover but not a vigorous grower.
Zieria smithii None
2.0 x1.5
White or pink Not spectacular but very hardy - may self sow

The plants in this group are generally adapted to nutrient-deficient soils are are not demanding as far as fertilizing is concerned. They do respond to applications of slow release fertilizer applied after flowering. If desired, the plant can be pruned back by about one third after flowering to promote a bushy habit of growth.

Plants are sometimes attacked by scale insects which can be controlled by physical removal (for small plants) or by use of white oil.


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