General Description:

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 ovalifolia is the most widely cultivated member of the genus. It is typically a medium shrub to about 2.5 metres high. Despite the specific name, the leaves may be lance-shaped to almost circular as well as oval shaped. In some forms the leaves may be slightly toothed along the margins; they are up to about 15mm long and are highly aromatic. The flowers are usually purple or mauve but pink and white coloured forms are also known. Flowering is usually prolific with the flowers almost obscuring the foliage. A form with variegated foliage is in cultivation.

P.ovalifolia is quick growing and 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. Under dry conditions it will wilt noticeably but quickly recovers when watered. It is a good “indicator” of when watering is required in a garden generally.

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.