Not truly in the Oregano family, mexican mint or Coleus amboinicus is actually a perennial succulent from the mint family that is used for the same culinary purposes as oregano. Although it is often grown as a houseplant, mexican mint can be grown in the garden in warm weather. The flavor is exceptionally strong, so use a moderate amount of mexican mint when cooking.
I. Appearance and Characteristics
Coleus amboinicus, synonym Plectranthus amboinicus, is a semi-succulent perennial plant in the family Lamiaceae with a pungent oregano-like flavor and odor. Coleus amboinicus is considered to be native to parts of Africa, the Arabian Peninsula, and India, although it is widely cultivated and naturalized elsewhere in the tropics where it is used as a spice and ornamental plant. Common names in English include Indian borage, country borage, French thyme, Indian mint, Mexican mint, Cuban oregano, soup mint, Spanish thyme. The species epithet, amboinicus refers to Ambon Island, in Indonesia, where it was apparently encountered and described by João de Loureiro (1717–1791).
A member of the mint family Lamiaceae, Coleus amboinicus grows up to 1 m (3.3 ft) tall. The stem is fleshy, about 30–90 cm (12–35 in), either with long rigid hairs (hispidly villous) or densely covered with soft, short and erect hairs (tomentose). Old stems are smooth (glabrescent).
Leaves are 5–7 cm (2.0–2.8 in) by 4–6 cm (1.6–2.4 in), fleshy, undivided (simple), broad, egg/oval-shaped with a tapering tip (ovate). The margins are coarsely crenate to dentate-crenate except in the base. They are thickly studded with hairs (pubescent), with the lower surface possessing the most numerous glandular hairs, giving a frosted appearance. The petiole is 2–4.5 cm (0.79–1.77 in). The aroma of the leaves can be described as a pungent combination of the aromas of oregano, thyme, and turpentine. The taste of the leaves is described as being similar to the one of oregano, but with a sharp mint-like flavor.
Flowers are on a short stem (shortly pedicelled), pale purplish, in dense 10-20 (or more) flowered dense whorls (cymes), at distant intervals, in a long slender spike-like raceme. Rachis 10–20 cm (3.9–7.9 in), fleshy and pubescent. The bracts are broadly ovate, 3–4 cm (1.2–1.6 in) long, acute. The calyx is campanulate, 2–4 mm (0.079–0.157 in) long, hirsute and glandular, subequally 5-toothed, upper tooth broadly ovate-oblong, obtuse, abruptly acute, lateral and lower teeth acute. Corolla blue, curved and declinate, 8–12 mm (0.31–0.47 in) long, tube 3–4 mm (0.12–0.16 in) long. Trumpet-like widened; limb 2-lipped, upper lip short, erect, puberulent, lower lip long, concave. Filaments are fused below into a tube around the style.
The seeds (nutlets) are smooth, pale-brown, roundish flattened, c. 0.7 by 0.5 mm (0.028 by 0.020 in).
II. How to Grow and Care
Sunlight
Mexican mint prefers bright but indirect sunlight. A place where there is partial shade is ideal for the plant to grow. The plant losing leaves is an indication that there is too little sunlight, or it is too cold. If Mexican mint is planted indoors, avoid placing it in a place with too much sunlight in summer to prevent it from being burned. In winter, a place with sufficient sunlight is suitable.
Temperature and Humidity
Cuban oregano doesn’t tolerate temperatures colder than 40°F. Plan to bring it inside before the outdoor temperature cools. It also can be grown as a tropical houseplant all year round. It loves humidity. Indoors, mist the plant or use a humidifier if the humidity is low in the winter.
Watering
Due to its native tropical environment, mexican mint thrives in a hot and moist condition. It is crucial to water moderately and regularly. If it is planted indoors, water it every two to three days. When the temperature is high outside, water it more frequently. Whether indoors or outdoors, if the leaves are dropping, further watering is needed. Leaves turning yellow can be an indication of overwatering.
Soil
The optimum soil for Mexican mint should be high quality, fertile and well-draining with a pH range between 6-7 (slightly acidic). The plant is not resistant to drought, so the soil should be moist at all times. Prevent the soil from being waterlogged or cold to avoid root rot. If Mexican mint is planted in a container, to keep the soil moist, ensure that the pot is not too porous.
Fertilizing
Mexican mint does not require fertilizer, but fertilizer rich in nitrogen can keep the foliage looking bright and healthy. If your mexican mint is an outdoor plant, organic fertilizer or liquid water-soluble fertilizer would be ideal. If it is an indoor plant, slow-release fertilizer is advised.
Planting Instructions
Typically, it is best to plant Mexican mint outdoors in late spring, when temperatures are above 10 ℃. Ensure the size of the planting hole is roughly double the root ball size. Once you have lightly pressed the soil after planting, water the plant. If you plant mexican mint in a container, make regular checks whether it needs a larger pot. White roots on the edge of the root ball generally indicate that the plant needs to be repotted.
Pruning
A healthy mexican mint grows reasonably quickly and can reach up to 1 m tall. Because of this, regular pruning will keep it looking bushy and full. The plant growing too quickly could be an indication that it has received too much sunlight, so move it to a more shaded site to slow down its growth. To encourage denser foliage, pinch the shoots when Mexican mint gets too tall. You can remove the main stems of the plant to promote branching.
Propagation
If you or a friend already have a Cuban oregano plant, you can propagate cuttings quickly in your kitchen window with stem cuttings. Cut a 4- to 6-inch cutting of new growth from the plant. Remove the leaves from the bottom half of the cutting and drop the cutting in a glass or jar of water—preferably a clear glass so you can see when it roots. Put it on a sunny windowsill and change the water every couple of days.
In two to four weeks, when you see roots in the water, gently transfer the cutting to a 6-inch deep pot filled with potting mix. Cover all the roots and some of the stem where you removed the leaves. Tamp down the potting mix, water it, and put it back on the sunny windowsill or a similar protected area for a couple of months until the plant shows new growth. Don’t move it outside until the temperatures stay above 60°F.
You can also divide mature clumps of Cuban oregano in the garden using a sharp shovel and immediately plant them in the garden or in a container.
Potting and Repotting
If the Cuban oregano grows too large for its current container, repot it in a container that is an inch or two larger in diameter. Select a container with drainage holes and fill it with rich, well-draining potting soil or a cactus/succulent planting mix with a pH between 6.0 and 7.5.
Pests and Diseases
Thanks to its pungent odor, Cuban oregano doesn’t attract many insects. However, spider mites and mealybugs are attracted to the plant, so keep an eye open for those. Spray the plant with neem oil every day or two if you see an infestation.
III. Uses and Benefits
- Ornamental uses
Mexican mint is commonly found in partially sunny gardens where it provides an eye-catching splash of bright green. It is also often seen around porches and patios. Companion plants include those that also prefer this type of location, like the begonia, impatiens, coleus, and fuchsia. Gardeners grow it for its distinct aroma of oregano and as a source of herbs.
- Other uses
The leaves are strongly flavoured. The herb is used as a substitute for oregano to mask the strong odors and flavors of fish, mutton, and goat. Fresh leaves are used to scent laundry and hair. In the southern Indian state of Karnataka, it is batter fried to make pakodas. The leaves can be used to make rasam and a herbal remedy (kashayam) that offers symptomatic relief from cold and sniffles.
