Coleus, made popular as Victorian-era bedding plants, have made a huge comeback thanks to the all-season color the lovely foliage offers whether it's planted in full sun or shade. Coleus plants are characterized by square stems and leaves situated directly opposite one another. Though it produces tiny blue to white flowers, they are insignificant and are often pinched off to conserve the plant's energy. The foliage can vary widely in shape, style, and color. Breeders regularly produce new introductions with even more unusual colors and patterns.
Planted outdoors in early spring, coleus quickly grows to full size in a single season. Large swaths of assorted coleus plantings that take on a quilt-like appearance can look luscious in a landscape or garden beds. Its vividly colored foliage also adds a decorative touch to window boxes, outdoor container gardens, and hanging baskets. Coleus is toxic to pets.
|Botanical Name||Plectranthus scutellarioides|
|Plant Type||Herbacious perennial (usually grown as an annual)|
|Mature Size||6-36 in. tall and wide|
|Sun Exposure||Part shade to full shade|
|Soil Type||Rich, moist, loose soil|
|Soil pH||Slightly acidic to neutral (6.0 to 7.0)|
|Flower Color||Blue to white|
|Hardiness Zones||10-11 (USDA); grown as an annual everywhere|
|Toxicity||Toxic to animals|
Coleus is a tender tropical plant, native to areas bordering the equator. Warmer zones can grow coleus as garden perennials, where they can grow to resemble small shrubs with thick woody stems. Though it loves the heat, it will happily grow as an annual in just about any garden, where it's normally used as an annual bedding plant or in containers.
However, coleus plants are not at all frost-tolerant, so don’t rush to get your plants in the ground. Wait until temperatures remain reliably above 60 degrees Fahrenheit before you move them out in the garden. They will do best in rich, loose soil, so amending with compost or peat moss before planting is advised unless you have very good soil.
Coleus is a classic part-shade to full-shade plant, but light exposure depends on the variety. The old-fashioned seed-grown coleus does best in part shade to full shade, but the newer cultivars have their best color if grown where they can receive more sun. However, it also depends on your climate. If you live in a hot, dry area, all types will need some shade, especially in the afternoon. In cooler areas with shorter seasons, the shade coleus will need more sun exposure to help them warm up.
Plants grown in containers indoors usually get plenty of light from indirect sun during the warmer (brighter) months but may need to be exposed to filtered sunlight during the winter. It doesn't take much, but they do need some light.
Coleus prefers a consistently moist, rich, loose soil. Before planting, amend the soil with compost or another organic material. For potted plants, any good-quality peat-based potting mix will work fine.
Container-grown coleus loves the loose texture of potting soil, and it always helps to start with a quality mix with a slightly acidic to neutral pH of 6.0 to 7.0. Provide drainage in the pot to ensure the soil isn't constantly wet, which leads to root rot.
Coleus plants grow best in soil that is consistently moist but not soggy. The soil should not remain wet all the time, but long dry spells will slow the plants’ growth, and the leaves will start to turn brown around the edges. Mulch will help the soil retain moisture longer, but don't use cedar mulch, which can be toxic to coleus. Also, don't let the mulch touch the stems, as it can promote rot and hide slugs.
Coleus in containers may need watering twice a day during hot weather. Outdoor containers may require water twice a day. Indoor plants need water only once every two or three days, or a bit more if you live in a dry climate.
Temperature and Humidity
As a tropical plant, coleus thrives in hot, humid conditions. In temperate climates, the barest hint of frost will spell the end of the plants. Make sure to take cuttings for propagation before the weather turns cold.
Keep indoor plants away from air conditioner vents and other cold spots. In dry climates, the plants will like some humidity from a humidifier or a bathroom environment. To take potted plants outdoors in spring, wait until the temperature is 70 degrees Fahrenheit or warmer.
If you have rich soil, you may not need to feed coleus plants at all. If you have poor soil, give the plants a monthly feeding with a balanced fertilizer mixed at half strength. You’ll get the best color from your coleus leaves if you go easy on the fertilizer.
Container-grown plants can benefit from a slow-release fertilizer added to the potting soil when starting a new pot. Thereafter, feed with a diluted liquid fertilizer given every one to two weeks. Container plants generally need more feeding than garden plants because frequent watering washes nutrients from the potting soil.
Types of Coleus
There are many dozens of coleus cultivars available with various colors, leaf textures, and patterns. Additional cultivars are developed each year, and garden centers tend to focus on a select few that have proven to be most popular among their customers. You may have to shop several different nurseries or online retailers to find the most unique varieties. Some types to look for include:
- Wizard series: These are small 12- to 14-inch plants in standard color mixes. They are known to be very easy to grow from seeds.
- Kong series: These coleus varieties have huge 6-inch leaves on big 2-foot tall plants. They are quite sensitive to direct sunlight.
- 'Black Dragon': This unusual variety has deep burgundy leaves with ruffled edges. They grow to 18 inches tall.
- Premium Sun series: These cultivars are bred to tolerate full sun.
- Fairway series: These are dwarf coleus varieties, only 6 to 10 inches tall, in a variety of leaf patterns and colors.
To get full, bushy plants, pinch out the growing tips when the plants are about 6 inches tall. Pinch under the flower buds if you want the plant to spend its energy on leaves and not flowers and seeds.
Plants that are not pruned tend to get leggy and lose their nice shape and dense foliage. If they remain leggy, the plants may need more sun. This is most common with indoor plants during winter so give them a bit more sun or, if necessary, artificial light.
Favorite coleus plants can easily be propagated by taking stem cuttings and rooting them.
- With a sharp shearing scissor, cut a 4- to 6-inch long stem tip, then remove all leaves from the lower half of the cutting.
- Dip the end of the stem in a rooting hormone compound, then plant it in a moist potting mix so the soil covers the exposed leaf nodes.
- Place the container in a plastic bag, making sure the plastic doesn't touch the cutting.
- Place the covered cutting in a bright, warm location until new roots develop, which will take two to three weeks.
- Remove the plastic and continue to grow the new plant in a bright, warm location.
Some of the more unusual cultivars might be reluctant to root, so with these, take plenty of cuttings to ensure that you get enough viable plants.
How to Grow Coleus From Seed
Modern coleus varieties sold in stores are hybrids that are almost always grown from cuttings potted up for nursery sale, but you can still find seeds of many varieties. If you will be planting the coleus in the outdoor garden, start seeds indoors about eight to 10 weeks before your last frost date.
It's easy to grow coleus from seed. It can take as long as 21 days for the seeds to germinate, so be patient. Once seedlings appear, it will take three or four weeks of warm weather to help turn them into fully grown plants.
- Lightly sprinkle the tiny seeds over a tray filled with potting mix, then lightly cover with a sprinkling of soil.
- Cover the tray with plastic and set it in a bright, warm spot until seedlings sprout, which takes about two weeks.
- Remove the plastic and continue to grow the seedlings while keeping the soil moist.
- When two sets of true leaves appear on the seedlings, carefully transplant them into their own pots and continue growing them until outdoor planting time.
Potting and Repotting Coleus
To grow coleus in a container, start with a large pot that the plant can grow into, otherwise, you'll be repotting this fast-growing plant before you know it. When using terra cotta pots for coleus, it helps to line the pot with plastic to help retain moisture in the soil.
In mixed container plantings, coleus usually serves as an upright "thriller" plant in the center of the container, surrounded by "fillers" and "spillers." In colder zones, container plants are sometimes moved indoors to overwinter.
Common Pests & Plant Diseases
Coleus is not usually bothered by diseases unless the weather turns cool and damp. If that happens, expect to see signs of fungal diseases such as mildew. If you are growing your plants indoors, watch out for scale, whiteflies, and especially mealybugs.
Is coleus easy to care for?
Coleus is very easy to care for. If you plant coleus in containers, you may want to bring it indoors during the winter to help it survive.
How fast does coleus grow?
Coleus quickly grows to full size, potentially up to 36 inches high, in a single season.
Can coleus be grown indoors?
American Society for the Prevention of Cruelty to Animals. "Coleus." Aspca.org. N.p., n.d. Web.