Plectranthus scutellarioides, commonly known as coleus, is a species of flowering plant in the family Lamiaceae (the mint or deadnettle family), native to southeast Asia and Malaysia. Growing to 60-75cm (24-30in) tall and wide, it is a bushy, woody-based evergreen perennial, widely grown for its highly decorative variegated leaves. Another common name is painted nettle, reflecting its relationship of deadnettles which are in the same family. (True nettles and their close kin are in the Urticaceae.)

The name "coleus", still widely used by horticulturalists and gardeners, refers to a defunct genus, and may be regarded as a common name for this species in particular. The obsolete name Solenostemon scutellarioides is similarly widely used for this species.
The specific epithet scutellarioides means "resembling the genus Scutellaria", also in the Lamiaceae, whose name is itself derived from the Latin scutella, meaning a small dish or bowl.
Leaves typically show sharp contrasts between their colors; particular leaves may be several shades of green, pink, yellow, "black" (a very dark purple), maroon, cream, white, and red (somewhat resembling the unrelated Caladium). New cultivars with different color combinations are constantly being made. The following hybrid cultivars have gained the Royal Horticultural Society's Award of Garden Merit:-
Plectranthus scutellarioides color variation is mostly dependent on how much sunlight is available and how intense that light is. In this species, green coloration is due to the amount of chlorophyll present in the chloroplasts in the leaves. The genus Plectranthus has green leaves with bright reds, purples, pinks, and oranges. These variations in color are due to anthocyanins, water-soluble, flavonoid biosynthetic pigments, found in the foliage in addition to chlorophyll. The increase in anthocyanin production is accompanied by a decrease in chlorophyll production. The production of anthocyanins and chlorophylls are affected by light; the more light is present, the more anthocyanins are produced, with an inverse relationship to the production of chlorophylls. Anthocyanins are created inside the cell and facilitate photosynthesis in leaves that are exposed to very intense or prolonged sunlight. Leaves in Plectranthus scutellarioides varieties that are not exposed to intense or prolonged sunlight have a higher concentration of chlorophylls than anthocyanins.[verification needed] Different balances of pigmentation chemicals produce a wide variety in Plectranthus scutellarioides foliage colors.
The genus Plectranthus is native to many tropical areas in Asia, Australia, and Africa. These tropical areas, because of the extreme diversity of flora, have many different habitats that greatly vary in light intensity. Plectranthus scutellarioides plants that grow in areas exposed to extended periods of light tend to display brighter and more variegated leaves. Plectranthus scutellarioides plants that grow in areas near the floor of tropical forests, and therefore are exposed to less light, often have greener foliage. The genus Plectranthus has evolved species which live under different light-availability conditions.
The plants grow well in moist well-drained soil, and typically grow 0.5-1 m tall, though some may grow as tall as 2 meters. Coleus are typically grown as ornamental plants. They are heat-tolerant, but they do less well in full sun in subtropical areas than in the shade. In areas without freezing temperatures, plants can usually be kept as perennials if well managed. In colder areas, they are often grown as annuals, since the plants are not hardy and become leggy with age (to encourage bushing in leggy plants, simply pinch back growing tips). In bright, hot areas, the colors of the plant are typically more intense in shade than in full sun, and the plants require less water there. Coleus also make low-maintenance houseplants, and can often be propagated by clipping a link of stem just below the leaves and putting the stem in water to root. This species' flowers occur in terminal inflorescences of shoots, and are small, and white through bluish and purple. People often remove young inflorescences to keep the plants more compact.
The downy mildew Peronospora sp. makes leaves brownish and can also cause leaf curling and twisting. It is harder to control this mildew on stems compared to leaves. Another disease is impatiens necrotic spot virus which causes brown or yellow spots on leaves, rings, black or brown stem discoloration, and brown leaf veins, ultimately resulting in plant death. The disease is spread by an insect called a thrips that carries the virus from an infected plant to an uninfected one. It only takes a few of these insects to infect a whole greenhouse.
There are two ways to propagate Coleus. Seeds are inexpensive and easily obtainable, though named cultivars do not come true from seeds. To germinate seeds, simply sprinkle seeds on the soil surface and press down. Seeds require light to germinate, so avoid covering the seeds. To keep seeds moist, grow in a container and cover with plastic, or mist seeds daily (if starting seeds directly in the garden). Sprouts can show color in as little as two weeks. Alternatively, cuttings can be taken. Cuttings root readily in plain water, without the addition of rooting hormone (although it is still beneficial).
Coleus blumei (now known as Plectranthus scutellarioides) has been reported to have very mild relaxing and/or hallucinogenic effects when consumed. The effects of the Coleus plant have not been explored very much by modern scientists but the plant has been known to have been used by the Mazatec Indians of southern Mexico who have a history of consuming this plant for its mind-altering effects. It is not known what psychoactive chemical(s) exist in the Coleus blumei plant, as there has been very little research on the subject.
Some people have claimed that they have experienced hallucinogenic effects from chewing several dozen fresh coleus leaves as a quid or brewing them to make a tea, although others have reported feeling no effects at all.
Several authors of internet-hosted trip reports have claimed that smoking dried coleus leaves causes effects similar to smoking dried Salvia divinorum leaves, and the active compounds in the two plants may have similar chemical structures. However, some authors claim that only the fresh leaves of the Coleus blumei plant are psychoactive.