Prostanthera rotundifolia
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AUSTRALIAN MINT BUSH
Family: Lamiaceae
Pronounced: pros-tanth-E-ra ro-tun-di-FO-lee-a
GROWING GUIDE
Geographic Origin:
Australia and Tasmania.
Plant Group:
Shrubs.
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Mature size: Height: 6 feet (2 m). Width: 5 feet (1.5 m).
Flowering period: Mid-spring to early summer.
Flowering attributes: Bell-shaped, pale purple flowers.
Leaf attributes: Round to ovate, aromatic, evergreen leaves.
Light: Full sun in the Pacific Northwest.
Soil: Fertile, well-drained, moist soil.
Feeding: Side dress with a complete organic fertilizer and compost or manure in spring. Fertilize again after flowering.
Propagation Methods: Sow seed 55-64°F (13-18°C); seed is slow to germinate. | Semi-ripe cuttings in summer.
Pruning Methods: Lightly prune after flowering, if needed. Hard pruning may kill the plant.
Rainy Side Notes
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Prostanthera rotundifolia is one of the hardier members in this genus. One nursery reports that a specimen in a 5-gallon container survived several days of 15°F weather, even when the soil in the container froze. In my first attempt growing it, I lost it over a mild winter. With my next attempt with a new plant, it survived down to 18°F and is now reaching its mature height. Try growing in a protected area or pot it up and bring under glass during the winter. If you want to take a risk and grow it outdoors, take insurance cuttings until you establish that it can survive in your garden. After several years it reached nine feet tall and about four feet wide, larger than what the sources give as six feet tall.
The Australian aborigines used the leaves in an infusion for relief of headaches and colds. The small mint flavored leaves are used for culinary purposes and for potpourris.
Debra Teachout-Teashon
Photographed in author's garden.
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