By Julie Christensen
Coleus (Solenostemon scutellarioides), with its beautiful, heart-shaped foliage, is the darling of the annual shade garden (though some varieties are adapted to full sun). If you’ve never grown coleus before, you’ll be surprised by the stunning variety of colors and foliage. Although coleus does produce flowers in late summer, it is grown chiefly for its foliage, which comes in brilliant shades of fuchsia, lime, pale yellow, dark green, purple and even black.
Coleus, also known as flame nettle or painted leaf, is a tropical plant, hardy only in U.S.D.A. plant hardiness zones 10 and 11. Elsewhere, it is used as a fast-growing annual. Plant it in the spring after the last frost and it quickly attains its mature height of 1 to 2 feet, depending on the variety. Some cultivars have a trailing habit, making them ideal for container culture.
Plant coleus in containers as an accent plant for other annuals or use it as a bedding plant in shady areas. Coleus is generally grown from nursery transplants, but you can also start it from seed — an economical choice if you want to fill a large area. Start seeds 6 to 8 weeks before the last expected frost. Sow the seeds in slightly moist, light potting mix, but do not cover them with soil because they need light to germinate. Cover the seed tray with plastic wrap and store it in a warm location. Seeds germinate within one to two weeks at 70 to 75 degrees Fahrenheit.
Another option is to take soft cuttings in late summer before frost nips the plants. Cut a 6-inch piece from the youngest part of the plant. Remove the leaves from the bottom 3 inches and dip the bottom of the stem in rooting hormone. Place the cutting in a pot filled with sand or vermiculite and keep it warm and moist. New roots should form within a few weeks, and the plant can be planted in pots. Plant young plants outdoors only after the last expected frost, as they are very sensitive to cold temperatures.
Coleus Growing Tips
Coleus grows best in a light, well-draining soil. Plant it in sun or shade, depending on the variety. Immediately after planting, keep the soil moist, but not soggy. Coleus doesn’t tolerate wet feet. Once the plant becomes established and puts out new growth, cut back on the moisture. Water coleus only when the top 1 inch of soil is dry.
Fertilize coleus monthly during the growing season with a liquid fertilizer. Dilute it to half the amount recommended on the label. Pinch it back frequently to encourage compact, leafy growth and remove any blossoms. If flowers are allowed to remain, the plant dwindles and becomes straggly.
Coleus is fairly disease-resistant, but does suffer from root rot, which is evidenced by stunted growth and browned, muddy-looking leaves. Prevent this disease by planting coleus in well-draining soil and avoid overwatering it. Drip irrigation is preferable to overhead sprinklers. Aphids sometimes bother these plants, although the damage is rarely severe. Spray them with a steady stream of water or apply insecticidal soap or oil to both sides of the leaves. Make these applications on cloudy days, though, because sunlight can scorch the leaves.
For sunny locations, try ‘Alabama Sunset,’ an old favorite with southern gardeners. This plant is sterile and produces few blooms. It has pink to fuchsia leaves and grows 12 to 18 inches tall. ‘Burgundy Sun’ grows 2 feet tall and produces deep burgundy leaves. ‘Pineapple’ has brilliant lime green leaves with a burgundy edge. ‘Solar Eclipse’ has bright red leaves with black margins, while ‘Plum Parfait’ has serrated, ruffly leaves in deep purple.
In dappled to full shade, try ‘Dark Star,’ a black coleus, or ‘Fishnet Stockings,’ which has lime green leaves covered with purple veins. ‘Freckles’ has green leaves with red spots, while ‘Japanese Giant’ has large pink and violet leaves.
Part of the fun of growing coleus is experimenting with new colors and varieties. Coleus can be formal and traditional or downright playful, depending on the cultivar and planting technique. Try a few this season to enliven your containers or annual beds.
Learn More About Coleus:
Coleus from Clemson University Cooperative Extension
Coleus from Cornell University Home Gardening
Skip Richter with Agrilife.org talks about Coleus in his YouTube video.
When she’s not writing about gardening, food and canning, Julie Christensen enjoys spending time in her gardens, which include perennials, vegetables and fruit trees. She’s written hundreds of gardening articles for the Gardening Channel, Garden Guides and San Francisco Gate, as well as several e-books.