How to grow colorful coleus
The Gardener Within: Master gardener and author Joe Lamp'l shares planting and growing tips for colorful coleus.
Scripps Howard News Service
When you think of the incredible colors of a summer garden you think flowers, right? But exuberant color doesn't always need dazzling flowers and shimmering summer sunshine. You can have displays of incredible color in lower light without a flower in sight, thanks to coleus.
Coleus is a member of the mint family, with its characteristic square stems and oppositely arranged leaves. It's actually a heat-loving herbaceous perennial, but is usually treated as an annual, since even the slightest breath of frost will turn it to mush. There are no USDA zones warm enough to grow it through the winter consistently. In spring, when the soil temperature stays above 55 degrees F, it's time to plant in part-sun and well-drained soil.
The colorful leaves come in many shades of purple, red, orange, pink, green and yellow — just about every color except blue — in dozens of patterns, shapes and sizes, from tiny, spotted and marbled to gigantic, toothed, lobed and divided. They come in upright form, mounding, creeping and trailing. And while coleus can be overwintered in pots in the house, the mature plants are more likely to bloom or harbor pests and diseases. It's better to take cuttings or buy new plants each spring.
Morning sun and afternoon shade is the rule of thumb for any coleus. But breeders have been introducing lots of sun-tolerant varieties that can take a lot more light than many of the older hybrids. Most have "solar" or "sun" in their names, and sport brighter reds and more vivid greens in their foliage. Coleus with variegated leaves of white, cream or yellow will turn green in too much sun.
Coleus likes even moisture best, but in shade will do better with drier soil. In full sun, be sure to give all coleus plenty of water. It may wilt in high heat, but will spring back quickly when given a drink. A 2- to 3-inch layer of mulch over the soil will help retain much-needed moisture down by the roots. Even with its fabulous color, coleus doesn't need a lot of feeding. My plants stay looking great all season simply by planting in compost-rich soil.
Coleus grows quickly. When the plant is getting started, pinch the stems back by about one-third to keep them compact and full. Deadhead any flowers you see developing to keep the plant robust and growing strong. Grown outdoors, coleus is largely pest-free. Inside, keep an eye out for mealy bugs, spider mites and aphids. An occasional spray of insecticidal soap should keep them under control.
Most coleus mail-order and Internet sources sell named varieties, while the cheaper garden-center offerings sometimes go unidentified. There can be a lot of confusion about cultivar names, but with so many to choose from, just pick the ones that catch your eye! Here are a few favorites, listed by characteristic, to get you started.
Best in sun
"Wasabi" — Stunning colors and patterns for full sun and shade. Durable and rugged, the serrated chartreuse leaves hold their brilliant color without fading or spotting.
"JoDonna" — Burgundy centers surrounded by bright lime green; 30 inches tall.
"Solar Eclipse" — Black marks in a highly toothed, cherry-red leaf; 18 inches tall.
"Solar Flare" — Wide, light-green leaves with yellow edges and red centers; 24 inches tall.
Best in shade
"Diablo" — Long, red-ruffled leaves with black centers; 34 inches tall.
"Black Magic" — Purple-brown, scalloped leaves; 12 inches tall.
"Butter Cream" — Heavily ruffled green edges and a pale cream center; 18 inches tall.
"Gold Brocade" — Gold leaves speckled with vibrant purple and red; 18 inches tall.
"Bipolar By Golly" — Pale lavender with red and yellow speckles; 28 inches tall.
"Kaleidoscope" — Lemon yellow with outlandish streaks of red and bright green centers; 30 inches tall.
Short and trailing
"Red Trailing Queen" — Red leaves rimmed in green lobes; 12 inches tall.
"Thumbellina" — Tiny, 1-inch leaves in green and burgundy; 6 inches tall.
"Trailing Salamander" — Black with green edges; 12 inches tall.
Joe Lamp"l, host of "Growing a Greener World" on PBS, is a master gardener and author. For more information, visit www.joegardener.com.
When selecting any plants, be aware of which ones may be considered noxious weeds in your area. If you're not sure what plants may be invasive in your area, check with your local garden center, horticultural office or noxious weed control board.