Poliomintha

( poh - lih - oh - MIN - thuh )

At-A-Glance Information

This genus of evergreen shrubs, commonly known as Rosemary Mint, needs regular water and has varying exposure requirements, depending on the species. The flowers will attract hummingbirds to your garden. Rosemary Mint is native to the southwestern United States, Mexico, and and Haiti. Foliage is fragrant, and flowers are pink.

Poliomintha Species and Varietals

There are about 8 species within the genus Poliomintha, which is a member of the plant family Lamiaceae. The genus name is derived from the Greek words for grey ('polios') and mint ('mintha'). Relatives of Mint, Poliomintha growing zones vary depending on the species. For more information, see the descriptions below. To find your zone, click here: Zone Map.

​Poliomintha incana (Frosted Mint)
Native to the southwestern United States and northern Mexico, this species forms a strongly aromatic shrub with dark green leaves. Small white hairs cover foliage. Flowers are tubular and also fuzzy, typically in light purple to light blue. The foliage of these plants is used fresh or dried as a culinary flavoring.

​Poliomintha maderensis (Poliomintha longiflora) (Mexican Oregano, Lavender Spice)
This well-known species of Poliomintha is best in zones 8-24 and is native to eastern Mexico. It reaches 3 feet tall and wide with shiny green leaves that have the odor and flavor of Origanum. Flowers begin lavender, and mature to a darker violet, eventually fading to white. Blooming season is spring through fall, and stems are brittle. Keep this plant away from high traffic areas. Needs light shade in hot areas, but can take full shade elsewhere. 

Caring for and pruning poliomintha shrubs

Plant Poliomintha shrubs in full sun. These shrubs need at least 6-8 hours of direct sunlight per grow to have full foliage and produce profuse flowers. Ensure that soil is well-draining; sandy or loamy soils are ideal for Rosemary Mint. They tolerate soil that is slightly alkaline to slightly acidic (with a pH of between 6.6 and 8.5). Although these plants are drought-tolerant once they are mature, they do need regular water when they are newly planted. Once established, water sparingly, allowing the soil to dry out  between waterings. Overwatering can quickly lead to root rot issues. 

Prune frequently to promote a bushier growth habit and to maintain their nice shape. Pinch back new stems to encourage branching as they are putting out growth in the springtime. Deadhead frequently to encourage new blooms to pop. In late fall, prune back plants to reduce their vulnerability to cooler temperatures. In wintertime, these plants can be brought indoors if they are planted in a container, or given protection if in the ground.

Harvesting Rosemary Mint
Leaves can be harvested as they appear on the plant, or after they have dried, and can be used fresh or dried. The stems can be used as a skewers for kebabs or vegetable brochettes. Use the leaves to flavor recipes that can take strong Oregano flavors, like tomato sauces for pizzas or pastas, teas, and salads. They can be used to flavor vinegars and oils, and the flowers can be used to add beautiful garnish to dishes (they are also edible).

Propagation

Poliomintha 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 Poliomintha by Cutting
  1. 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.
  2. 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 3-4 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.
  3. 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.
  4. 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 Poliomintha by Seed
  1. 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.
  2. 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 usually takes 7-14 days 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.
  3. 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

Rosemary Mint shrubs are pretty pest and disease-free plants, though they can occasionally be bothered by the following issues:
  • Aphids
  • Spider Mites
  • Root Rot
For more information about these issues, including how to treat them, see the following links:

Gallery

These water-wise plants do well in naturalized gardens.
Rosemary Mint does well when planted with other low water-use plants, like Agave and Penstemon.
The shrubs flower profusely in spring and summer, and foliage is aromatic.

Videos

All about the Mexican Oregano Plant (Poliomintha longiflora).
See Poliomintha featured in this video.

Resources

Mexican Oregono (Poliomintha 
Wikipedia: Poliomintha
The New Sunset Western Garden Book: The Ultimate Gardening Guide (2012) - Pages 522 - 523, Poliomintha
If you have any questions, comments, concerns, or photos you’d like to add to the gallery, please let me know by sending me a message using the button below!
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