The colourful Coleus

Editor's Note: The Gardening Guru had to go out of town to work for two weeks. Last week she wrote part 1 of a 2 part series. She plans to submit part 2 when she is back.

By Melanie Mathieson
Gardening Guru

The coleus plant has been available to gardeners for decades in a large variety of colours. In the past, they were a favourite for planters and shade gardens because they are durable and easy to grow and are best known for their bright colors and variety of foliage forms. It is interesting to note that coleus is from the mint family and is related to other plants such as ajuga, sage, thyme, basil, bee balm, lamb’s ears, lavender, lamium and nettles.
In recent years, the coleus has had a bit of a makeover resulting in some new hybridized varieties. Today the colour and foliage appeal seems to be endless with the addition of many new plants that will now thrive in a variety of light conditions ranging from full sunlight to partial shade.
Coleus plants may be grown in the garden in bright, indirect light, or in partial shade. The intensity of light which the plant receives will also have a direct bearing on the intensity of the foliage coloring. Some varieties may produce their best color in light shade, while others look best in bright lighting. Make sure you check the care tag in the container before you buy in order to get the plants with the proper light requirements for your needs. The lower growing dwarf varieties (6-12 inch) will create a colourful border or you can use the taller (three foot) types as a dramatic background planting. Coleus are also quite striking when they are planted in a container or you can also use coleus for mass plantings, a front of back border or as a companion plant to something else. The mixtures of foliage and colours with other perennials and annuals can be endless.
In our area, coleus is considered a tender annual as even the slightest frost will cause them to die. Coleus like an evenly moist soil, that drains well. Make sure your plants that are in the bright sun receive adequate amounts of water. The first sign or wilt indicates that they need to be watered. Pinch the center stems out when the plants are 4 to 6 inches tall to induce bushier growth and be sure to pick off the flower spikes as they form. Apply a good fertilizer in the same regime you have for your other annuals.
Expanding your coleus collection is quite easy as seeds are inexpensive, readily available, can be sprouted and begin showing their first leaf colors in as little as two weeks. Another advantage to growing coleus this way, is that each packet of seeds will contain many different colors of plants which you can choose your favourites to clone for the future, by taking cuttings. If your intent is to grow your coleus as a house plant, the HYPERLINK “http://www.thegardenhelper.com/growingseeds.html” \t “_blank” seed may be sown indoors, at any time of the year. If the seedlings are destined for a garden location, they should be started indoors, at least 10 weeks before your last expected frost, so that the plants will be well developed when it is time to plant them outdoors. Be careful when you open the seed packet as coleus seeds are very small. Sow the seeds onto a layer of moistened sterile potting soil in a shallow tray then cover with a thin layer of fine soil. The tray should be kept in order to retain moisture until the seeds have sprouted. Keep the tray in a warm (65-75 degrees Fahrenheit) and bright place but not in the full sun. When the seedlings are large enough to handle easily, they should be thinned out and HYPERLINK “http://www.thegardenhelper.com/planters.html” \t “_blank” transplanted into individual pots. Because they are very fragile at this stage, seedlings should always be held by a leaf, never by the stem) When all danger of frost is past, the plants may be set out in the garden.
You can also HYPERLINK “http://www.thegardenhelper.com/cuttings.html” \t “_blank” propagate coleus by taking and rooting cuttings, which creates a clone of the initial plant. Use a sharp clean knife to cut the stem just below a leaf node. Remove the lowest leaves, dip the cut end into a rooting hormone and insert it into some fresh, sterile potting soil. They will also root quickly when set in moist sand or vermiculite or even in a glass of room temperature tap water. If you take cuttings in the fall, prior to a killing frost, can grow your coleus as a house plant. As older plants tend to become leggy and the foliage colour will begin to fade, in February or March take several cuttings from this plant and cultivate them to transplant into the garden for when the weather warms. Propagation by cuttings is an effective way to renew an older plant as “cloned” baby will quickly become the better plant.
Coleus make nice houseplants as long as they receives sufficient light and food. Your Coleus should be planted in a light, quick draining commercial potting soil. Place it where it will receive several hours of bright light (south window) each day or provide artificial grow lighting for best leaf color and fullness. Coleus plants will adapt to a wide range of temperatures above 55 degrees Fahrenheit, but will grow best when they are kept between 70 and 85 degrees Fahrenheit. Keep the soil evenly moist, but never soggy. Fertilize coleus with houseplant fertilizer as per the instructions on the package. Flower buds must be pinched off as soon as they develop to prevent the plant from producing seeds because once a coleus is allowed to go to seed it has completed its life objective and will usually die. Pinching may also be necessary to prevent leggy growth. Any time that the tip growth is removed, the plant’s energy will be diverted to the lateral side growth, creating a much bushier plant. Coleus are very durable, so you can cut your plant back severely if needed.
So why don’t you try some coleus this season in your garden? I have had them in my containers at home and the office for the last two years and they have performed wonderfully.