Prostanthera
( pro - stan - THEIR - uh )
At-A-Glance InformationThis genus of evergreen shrubs and subshrubs, commonly called Mint Bush, needs full sun and moderate water to perform well. All species are native to Australia, and are prized for their fragrant foliage and profuse (though small) flowers that bloom in shades of blue, purple and white, often with patterned throats. They are short-lived but grow vigorously, and are used as ornamental plants as well as harvested for essential oils and spices.
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Prostanthera Species and Varietals
The genus Prostanthera includes around 100 species and is a member of the Mint family Lamiaceae. The genus was first described by Jaques Labillardiere in his book Novae Hollandiae Plantarum Specimen. Mint Bush grows well in zones 14-17 and 19-24, though this varies somewhat depending on the species. To find your zone, click here: Zone Map.
Prostanthera 'Poorinda Bride' This species has an upright growth to 4-6 feet tall and just as wide. Leaves are narrow and olive-green and flowers are white with shades of violet, and throats are marked with yellows and oranges. Blooms appear in late spring and summertime. Cut back by a third after blooms fade to keep a neat, compact habit. |
Prostanthera rotundifolia This species reaches 6 feet tall and 5 feet wide, with small round leaves and bluish purple flowers. Varieties include 'Ghost Cave' (with grey-green foliage purple flowers), 'Glen Davis' (with profuse dark purple flowers), and 'Rosea' (a plant reaching just 3-4 feet tall with dark green leaves and deep rosey-pink flowers). |
Caring for and pruning Prostanthera shrubs
Mint Bush does best in full sun (at least 6-8 hours of direct sun per day). They need well-draining soil with an acidic to neutral pH (between 6.1 and 7.8). Keep soil consistently moist but not waterlogged, and use deep waterings rather than regular frequent waterings. Reduce waterings in wintertime during the plant's dormancy. Mulch should be applied around the shrub's base to increase soil moisture retention. Feedings once a year with a balanced, slow-release fertilizer will assist with new growth and flowering. These shrubs or subshrubs can be grown either in the ground or in containers. Prune carefully; avoid cutting into bare wood or doing any other hard prunings. Prune to shape and maintain a manageable size as the plants are ending their flowering season. Light prunings to remove dead or damaged branches or foliage can be completed at any time of the year.
How to Harvest Prostanthera
Some Prostanthera species have foliage that can be used for their minty fragrance or as a culinary herb. Harvest leaves as needed for these purposes.
How to Harvest Prostanthera
Some Prostanthera species have foliage that can be used for their minty fragrance or as a culinary herb. Harvest leaves as needed for these purposes.
Propagation
Prostanthera can be propagated either by using cuttings or from seed. To ensure that your propagated plant will have the exact same qualities and characteristics as the parent plant, use the cutting method. If you would like to experiment and see what plant you can grow from seed, just keep in mind that it will not necessarily be the same as the parent plant. To propagate your shrub, follow the instructions below:
Propagating Prostanthera by Cutting
Propagating Prostanthera by Seed
Propagating Prostanthera by Cutting
- Gather your materials. You'll need a clean, sanitized, sharp pair of garden shears, rooting hormone, a pencil, and a 3-inch pot filled with well-draining compost or other organic material. If you don't have any potting medium on hand, you can make some. Just mix together equal parts (by volume) moss peat and horticultural-grade sand or grit sand.
- In spring or early summertime, choose the plant that you'd like to propagate. Ensure that this plant has had a good watering the night before, as this will improve the chances your cutting will take root. Cut one or more 6 inch portion(s) of the end of a non-blooming branch and strip the leaves off of the lower half. Make a hole in your planting medium by pushing your pencil into the soil. Dip the end of the stem in rooting hormone, and plant it in your pot. Fill in soil around the cutting to support it, but do not pack it down too much.
- Moisten with water, and ensure that the pot has good drainage. Your pot should be kept in warm, sunny conditions indoors (and not in direct sunlight). Water whenever your soil is dry under the top layer. After about four to six weeks have passed, your cutting should be rooted. When you notice new growth, you'll know you have roots.
- Keep your new plant in an area with bright light (though not direct sunlight) and temperatures between 55 and 70 degrees Fahrenheit. Ensure that the soil stays moist, but not wet, until the next spring, when you can transplant it to its new home. Ensure that the last frost of the year has occurred before doing this, as it can seriously damage your new shrub.
Propagating Prostanthera by Seed
- Keep in mind that the plant you get from seed will not necessarily mimic all of the characteristics of the parent plant. To propagate by seed, you will need a paper bag, a pot or tray filled with well-draining compost or other organic material, a spray bottle and a fork. If you don't have any potting medium on hand, you can make some. Just mix together equal parts (by volume) moss peat and horticultural-grade sand or grit sand. You will also, after a few weeks, need individual 3-inch pots for each seedling that grows.
- Water your prepared seed tray or pot filled with soil, and ensure that good drainage is occurring. Place your seeds in your prepared pot or seed tray about a quarter inch to a half-inch under the soil surface. Cover them with soil and water with your spray bottle. Place your tray of seeds in a warm area that receives bright, indirect light. A greenhouse is the most ideal climate, but a planting tray inside a window will do as well. Germination can take between 1 and 6 months from sowing. Once you begin to see seedlings sprout and they are able to be handled, transplant them to their own individual 3-inch pots, filled with the same potting medium as described in Step 1. Loosen the seedlings from the potting medium by digging down with the tines of your fork about an inch and a half, gently working the seedling up until it is out. Then, replant the seedling in its individual pot.
- Keep the seedling's potting medium moist, but not wet, by spraying the soil with your spray bottle. Keep your new plant in an area with bright light (though not direct sunlight) and temperatures between 55 and 70 degrees Fahrenheit. Ensure that the soil stays moist, but not wet, until the next spring (after the danger of frost has passed), when you can transplant it to its new home.
Problems and Pests
Prostanthera plants can suffer from the following common garden issues:
- Aphids
- Scale Insects
Gallery
Videos
All about growing and caring for Mint Bush.
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Learn about Prostanthera cuneata.
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Resources
The New Sunset Western Garden Book: The Ultimate Gardening Guide (2012) - Page 530, Prostanthera
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