Tidewater Gardening - July 2009
Easy Foliage Color in the Flower Garden
K. Marc Teffeau
An annual foliage plant (in our area – a perennial in tropical locales) that was a landscape mainstay in the past but fell out of popularity a number of years ago has made a comeback thanks to new and improved varieties. Coleus is a very easy plant to grow and quite versatile in its uses. Gardeners, looking for ways to bring continuous splashes of color into the annual landscape, in patio containers or in large beds, can find lots of applications with the white, pink, green, red, purple, yellow, burgundy and orange foliage colors of this annual. The leaves are irregularly toothed and marginally crisped and can be mottled and generally variegated. Currently there are over 600 cutting varieties and 30 seed varieties available on the market.
Coleus (Solenostemon scutellarioides) is a member of the Solenostemon genus of perennial plants native to tropical Africa, Asia, Australia, the East Indies, the Malay Archipelago and the Philippines. As a result they are heat tolerant but do require watering on a regular schedule. Gardening historians indicate that these plants were planted in American gardens in the 1800’s; they were very popular in Victorian gardens and were found in shady borders and pots. However, with changing gardening trends and tastes they fell out of favor. Breeding programs starting in the ’40s and culminating in the ’90s, produced an explosion of both sun and shade tolerant varieties which brought this plant back into favor. In addition, the popularity of container gardens and planters provided another venue for the display of these plants.
These plants offer a great versatility to accent existing plants or stand on their own in the landscape. The foliage of this annual does best in full sun to partial shade, depending on the variety or cultivar and moist, well-draining soil. On some varieties the leaf colors are even more vivid in partial shade. Since Coleus is a tender annual, at the first frost it will start to die. However, you can bring them indoors and protect them all winter long either by digging and planting in a container or taking stem cuttings.
The trick to having nice looking coleus is to keep them from growing straight up and then blooming and setting seed. The irregular, rather unattractive racemes of blue or lilac colored flowers that are produced during the summer months should be removed while in bud, as coleus is grown for its foliage, which is far more colorful than the flowers. Pinch out the terminal growing tips of the plants shoots about every four to six weeks to encourage lateral branching and more compact growth. This pinching also slows flower spike development. If you can keep your coleus from getting tall and gangly, bring them in before your first fall frost. They make attractive indoor plants during the winter months and can be set out again each spring.
Generally the best use of Coleus is in mass beds in the landscape rather than individual plants in a flower bed. For best effect plant coleus in large drifts or small groupings to highlight other plants or stand on its own merits. Space the plants about 18 inches apart, and add an application of a slow-release fertilizer at planting. Some cultivars only reach a height of six inches, while others grow up to three feet tall. Garden designers recommend, for example, planting a sweep of one type here and a mass of another type there. Creepers and spreaders, such as the Ducksfoot Series and ‘India Frills,’ are great for edging, filling in spaces between other plants, or cascading from hanging baskets and window boxes.
Large, shrubby selections (up to 36 inches tall), such as ‘Aurora’ and ‘Alabama Sunset,’ work well in the back of the border.
There are both sun-tolerant coleus and shade preferring types. The sun-tolerant enjoy being in full sun where their colors are at their best. While they will grow in the shade, the colors may get a little subdued or muddy. The shade preferring ones tend to bleach out if they are in full sun.
The sun preferring “Solar Series” coleus provides a whole color palette to choose from. ‘Solar Flare’ offers green leaves with a red center and yellow edge; ‘Solar Furnace’ has deep red leaves; ‘Solar Storm’ has multi-colored green, red, and bronze foliage; ‘Solar Eclipse’ produces cherry red leaves with black borders. One of the largest in the Solar series is ‘Solar Mahogany Mist’, which has huge multi-colored leaves on a large plant.
In the shade preferring line, The “Kong” group of coleus was introduced to the garden market in 2004. This is a shade coleus, propagated by seed, which looks like it is a sun coleus. Most shade-loving coleus are smaller and less vigorous that sun coleus. As exemplified by its name “Kong” coleus have big leaves on vibrantly colored big plants. The Kong series of coleus will not thrive in sun; fading and sun burn on the foliage will occur. Plant them in a location where morning sun may occasionally appear. Midday, afternoon and late summer evenings, the plants should be located in a partially shaded to fully shaded area. The Kong coleus is available in red, rose, mosaic and scarlet.
Coleus are very easy to propagate in the fall. Simply take a cutting about four to six inches long, remove the bottom leaves and place the leafless portion of the stem in a lightweight, soilless mixture. Keep the potted cutting indoors in a sunny window and mist as needed. Within a week or two, the cutting will develop roots and by next spring, you’ll be able to take it outdoors and enjoy your coleus once again.
Gardening activities do not go on vacation in July. If you are a vegetable grower start your broccoli, cabbage, and cauliflower seeds now so you can set them out as fall transplants in August.
It is difficult to locate fall vegetable transplants in this area as most greenhouse growers are oriented to the spring season. Mid to late July is a good time to direct seed lettuce, spinach, beets, carrots and turnips into the garden. They may be a little slow in germinating because of the high temperatures. Try lowering the soil temperatures by covering the seed bed with a floating row cover like “re-may” or some other shading material. Successive plantings of green beans can go in until the first of August. Wait until August for the fall planting of peas.
In the annuals department, pinch back snapdragons after blooming to promote a second flush of bloom. If some of your annuals have died, pull them out and add them to the compost pile. You can replant beds with hardy annuals or perennials such as pansies, calendulas, globe thistles or sea pinks. Get a second bloom from faded annuals by cutting back to approximately half their height, then fertilize with a liquid fertilizer or ½ cup of 5-10-10 per square yard of planted area, and apply a generous layer of mulch. Cut back and fertilize delphinium and phlox to encourage a second show of bloom and stake tall perennials to keep them from falling over.
Chrysanthemums should be lightly fertilized every two weeks with a water soluble fertilizer. To keep plants compact and full of blooms, pinch out new tip growth until eight weeks before they are to bloom, approximately mid-July. For large exhibition mums, allow only one or two shoots to develop. Stake these shoots and remove side buds as they start to develop.
You can continue to plant container grown and balled and burlapped shrubs and trees in the landscape during the summer as long as we are not in an extended spell of 90 degree weather. Wait until after the first frost to plant or transplant any bare root woody plant material. If you planted trees or shrubs this spring, be sure to keep them well watered during the dry summer spells but do not overwater them, especially if they are planted in heavy clay soils. Many times the home gardener is his/her own and the plant’s worst enemy when it comes to overwatering.