Coleus plants, part of the mint sub-branch of the nettle family, are a vividly colored, leafy plant that makes a great garden border. Their leaves can be red, pink, green, yellow, white, and in striking blends of these colors. Coleus also grow well indoors in containers, and can survive and thrive for years in the right conditions. Here are some mistakes to avoid when growing coleus outdoors or indoors.
Plant Coleus Outdoors in Warm Temperatures
Do not plant coleus outdoors in cold temperatures. Ensure the soil temperature has warmed above 50 degrees F. (10 C.) before planting coleus seedlings or mature plants outside. Coleus will grow most abundantly in temperatures above 70 degrees F. (21 C.).
Where to Plant Coleus Outdoors
Do not crowd coleus close together. They spread out to about 16 inches across, so keep the leaves from shading each other by planting at least 12 inches away from each other in the garden. Some coleus prefer bright sun, but most do best and achieve the most vivid color in partial shade.
Check the soil pH before planting, and adjust your soil if it is too acid. Coleus prefer a soil pH at 7, or slightly above. Add powdered lime to the soil if it is too acid, and avoid mulches made from pine or cedar needles or their bark.
How to Water and Fertilize Coleus
When you plant your coleus, water them until the soil is saturated. Avoid over-watering, as coleus can develop root rot and fungus diseases quickly in poorly drained soil. Make sure to fertilize just once a month with a balanced all purpose fertilizer, one of the 10-10-10 formulas. Use an inorganic mulch made from fine pebbles, as this will help conserve heat in the soil and retain moisture. Coleus will thrive in warm, well-drained soil.
Nip Flowering in the Bud
Do not allow your coleus to produce flowers and seeds, as they die soon afterward. Watch closely for the small flower buds that form on coleus and pinch them back as soon as they start to open. This will help direct growth toward the leaves. As well, pinch back the growing tips of the leaves every few weeks. This makes the coleus grow out to the sides of the main stems, for a bushier, more shrublike plant.
In mid-summer, feel free to trim back the coleus leaves to promote stronger growth. Trim off the top 1/3 to 1/2 of the stems and leaves.
Growing Coleus Indoors
Do not keep your indoor coleus plants in the dark. Plant them in a container at least 12 inches in diameter, and place them near a window that gets six or more hours of sunlight per day. Provide additional light, if needed, with a fluorescent lamp designed for gardening purposes. Fertilize them once a month with a 50 percent solution of liquid fertilizer specified for house plants. Pinch back the uppermost tips if the coleus is growing long stalks, and remove flower buds to prevent seed formation. Water once the soil has dried to a depth of two inches in the container.
Now that you have the knowhow, you can add a pop of color to your garden with coleus. These beauties will add flair to any room indoors as well.