Prostanthera is a genus of about 90 species which occur only in Australia. They are known generally as “mint bushes” because of the aromatic foliage of many species. As a member of the Lamiaceae, Prostanthera is related to a number of culinary herbs such as mint, thyme, oregano and sage.
Prostanthera stricta is an erect shrub to about 2 m high by a similar width with branches that are densely hairy. The leaves are oval shaped and up to 12 mm long and are also densely hairy. Like many mint bushes the leaves are highly aromatic. The flowers are seen in spring and are usually purple or mauve. Flowering is often prolific.
P.stricta is a hardy and quick growing plant which should be pruned back annually by about one third if a bushy shape is to be retained. Like most prostantheras it prefers a well drained, moist position with some shelter from direct summer sun.
Prostantheras respond to well to annual fertilising after flowering and are not as sensitive as some other Australian plants to phosphorus.
Propagation is easy from cuttings but seed can be slow to germinate. In areas where the root-rot fungus Phytophthora cinnamomi is a problem, grafting onto the related Westringia fruticosa is recommended.
* EPBC Act = Environment Protection and Biodiversity Conservation Act 1999;
ROTAP = Rare or Threatened Australian Plants (Briggs and Leigh, 1988)
For further information refer the Australian Plants at Risk page
Photo: Brian Walters