Coleus is a petite houseplant grown almost exclusively for its bold, colorful foliage. Surprising to most, coleus plants are actually members of the Lamiaceae—or mint—family, and, like peppermint, their leaves are sometimes used for medicinal purposes (though they are not particularly tasty).
Coleus plants are native to Asia and Australia and boast a variety of pigmented leaves, in shades of green, pink, white, cream, yellow, maroon, and purple. The plant is often started from seed around a month and a half before the last frost. It will grow rather quickly, often reaching mature, robust size in six to nine months. Their unique appearance and ease of care make them a popular houseplant choice for both novice and experienced gardeners.
|Botanical Name||Plectranthus scutellarioides (also referred to as coleus blumei in the past)|
|Plant Type||Herbaceous perennial|
|Mature Size||0.5–3 ft. tall, 0.5–3 ft. wide|
|Sun Exposure||Partial shade|
|Soil Type||Moist but well-drained|
|Soil pH||Neutral to acidic|
|Bloom Time||Summer (not showy)|
|Hardiness Zones||10, 11 (USDA)|
|Native Area||Asia, Australia|
|Toxicity||Toxic to dogs and cats|
Members of the coleus genus are hardy and attractive plants available in a wide range of sizes and colors. Some varieties grow like small bushes, making them inappropriate for indoor locations, while many other varieties thrive indoors in pots under the right conditions, which includes ample light and humidity.
Although the growing guidelines described here make it possible to grow coleus indoors year-round, coleus is often grown as an annual and discarded once it becomes leggy (a problem that can often be contained by pinching off new growth).
Coleus plants love bright light, though it's best to avoid direct midday sunlight, which can scorch the delicate leaves. Your best bet is to find a windowsill or other spot in your home that gets direct sunlight in the morning and bright, filtered like in the afternoon. It will be a bit of a balance—too much sun can fade the plant's colorful foliage, but too little can lead to less-than-vibrant hues.
Plant your coleus in a soil mixture that is moist but well-draining. Typically a generic potting mix will suffice just fine, but if you notice that you're having issues with too-damp soil, you can amend your mixture with a bit of perlite or vermiculite to aid in drainage.
It's important that you keep the soil of your coleus plants continuously moist throughout the year, though you can typically reduce your watering cadence in the winter months. A coleus plant's soil should never be allowed to dry out. To check and see if your plant is ready for a shower, stick your finger into the surface of the soil about two inches deep—if the soil you touch is dry, it's time for watering.
Temperature and Humidity
Coleus plants prefer an average temperature above 60 degrees Fahrenheit in the summer. In winter, they can tolerate a slightly lower temperature, though they should always be kept about 50 degrees Fahrenheit. High humidity is also preferred by the coleus, so try keeping your plant in a typically-humid room of the home, like the kitchen or bathroom. Otherwise, you can increase humidity by lightly misting the plant a few times a week (especially if it's looking droopy) or investing in a small space humidifier.
Though not a true necessity, coleus plants can benefit from feeding each spring with slow-release pellets, or weekly during their growing season with liquid fertilizer.
Is Coleus Toxic?
Unfortunately, the beautiful and exotic leaves of the coleus plant act as somewhat of a warning sign to pets like cats, dogs, and horses, who can become severely ill if they come in contact with—or ingest—the coleus plant. The trouble lies in the plant's essential oil, which can cause topical irritations or gastrointestinal symptoms. Though poisoning doesn't often lead to death, it should still be taken seriously. Contact your vet or emergency services if your pet has gotten into your coleus plant, or if you notice any of the below symptoms.
Symptoms of Poisoning
- Loss of appetite
- Pawing at the mouth
- Facial or mouth irritation
- Low body temperature
- Difficulty breathing
There are over 60 species of coleus, most native to Asia and Malaysia. However, virtually all of the coleus available are derived from the single plectranthus scutellarioides species, crossed with a few other species. Hybridizing work within this group has been extensive—there are literally hundreds, if not thousands, of cultivars. At the end of the day, you should buy coleus for its foliage and not worry too much about its parentage.
Coleus plants are widely recognized as some of the easiest plants to propagate and can be grown from seeds or cuttings. Coleus grown from cuttings will be identical to the parent plant, but plants grown from seed will be variable and might end up being quite different from the parent plants. Coleus plants that are grown specifically for propagation generally do not look as good as ones grown exclusively for their foliage. The energy of flowering usually saps the plants of some of their vitality, which is why many growers pinch off flowers.
Potting and Repotting Coleus
A large coleus plant can reach between two to three feet in height. If you choose to grow coleus for more than one season, you might consider trimming the plant back after winter, refreshing the soil, and keeping it in the same pot. Typically, coleus plants will only grow as large as their current pot allows, and will not outgrow their space. That being said, if you desire a larger plant, all you need to do is replant your coleus in a bigger pot and it will grow to accommodate its new container.
Common Pests and Diseases
Like any houseplant, the coleus is suspectable to a few pests and diseases, though no more so than is normal. The biggest issue is root rot, which can result from soil that doesn't drain well, or a pot that doesn't boast drainage holes. Beyond that, your coleus plant may also become afflicted with downy mildew, which is caused by excess humidity and can be spread by nearby plants.
When it comes to pests, you may spot the occasional sign of mealybugs, aphids, or spider mites on your plant. To treat these pests, you have a few options. You can either soak a pad with rubbing alcohol and remove them from the leaves with that, spray the plant with water and diluted soap, or treat the plant with a natural insecticide, like neem oil.