Coleus Care Information - Coleus

Coleus Care Information

Coleus Care Information
Rosy Dawn Gardens

Coleus are vibrantly hued foliage plants that provide constant color for containers and the landscape. All types of coleus are now in the genus Solenostemon scutellarioides, so technically the name "Coleus blumei" or "Coleus hybridus" no longer exists. Most of our plants labeled with the common name "Coleus" fall into the former Coleus blumei category, although some of the the trailing varieties were formerly labeled C. pumilus or C. rehneltianus. In the absence of a Coleus Society or registry for hybridizers, many Coleus cultivars have been claimed, renamed, and even patented by nurseries. Coleus are also very generous with producing "sports," which are mutations that can be propagated and sold as a new variety. The same sport may occur spontaneously at different nurseries and each might claim it as a new introduction and give it their own name. This causes a lot of confusion for Coleus collectors!

Native to Africa and Southeast Asia, Coleus are not perennial or winter hardy in any but the warmest climates. Coleus thrive in warmer temperatures, and are treated as an annual in the United States. There is no zone in the U.S. where it is considered totally safe to grow Coleus outdoors year 'round.

Our Coleus Plants: All of the Coleus sold by Rosy Dawn Gardens are propagated from cuttings. We do not sell seed-grown varieties. Our growing method uses a lightweight substrate in a biodegradable sleeve. This provide us with robust plants and the highest cutting success rate we have ever seen. This growing method has the additional advantage of being compact and lightweight, which helps keep our shipping costs as low as possible. Our coleus plants are ready to plant into pots or the ground, and there is no need to remove the fiber sleeve as the roots will grow through it.

Most plants that we ship are single or multi-stemmed and between four and twelve inches in height, depending on the cultivar. Coleus cultivars vary widely in height, leaf shape, and habit. Some coleus are small and grow very slowly, sometimes taking months to grow just a few inches in height. Others root rapidly and bolt out of the gate with vigorous growth. We try to indicate in the catalog descriptions when a plant is small or slow-growing, so please read carefully before ordering.

Please note: We grow and ship husky starter plants ready to pot up and grow on. They are not full grown plants! When planting in areas that receive a lot of sun or wind, make sure that your coleus have a chance to develop a good root system. The root-balls with which they arrive with might not be able to provide the coleus with enough water and nutrients to survive extreme outdoor conditions. Before exposing your new coleus to sun or wind they will need to be potted and grown on in a sheltered location until their root system is more developed.

When Your Plants Arrive: When you receive your order from Rosy Dawn Gardens, carefully unpack each plant and inspect it for any damage that may have been caused by shipping. Please notify us within 72 hours of any defects that you consider out of the normal range for plants that have spent the last few days in a closed box. Remove the plastic sleeve from each root ball, and make sure your new plants receive water and fresh air upon arrival. Please keep the plants out of wind and direct sun until they have hardened off. If you are unable to immediately put your new plants into soil please place them in a shallow waterproof container such as a cake pan or deli container until they can be planted. Keep the root balls moist, but do not allow your plants to stand in water as this could promote rot and disease.

Planting your new Coleus: You new Coleus plants should be planted in a good quality soil mix as soon as possible after arrival. If it will be a while before you will be able to place your new coleus plant in its permanent location, or if the coleus is going to be planted directly in the ground, the coleus should be planted in a 4" pot and grown on until transplant time. I week or two of this preparation will pay off in faster growth and happier plants. The sooner your plants are planted in soil the faster they will expand their root systems and reach their full potential! If your coleus are delivered before it is safe to place them outdoors (see below) then you must provide them a well-lit and warm spot indoors or in a greenhouse.

For their permanent home, a single coleus plant will do well planted in a 6"-8" pot, while three or four coleus may be planted in a 10"-12" (or larger) pot. All pots should have drainage holes. The soil mix should be high quality, airy, and well-drained, with lots of organic material. A time-release fertilizer for annual plants is highly recommended. Other products you may find useful are soil additives such as crystals that swell up into a jelly when water is applied. They are excellent for helping to keep coleus hydrated on hot days. They store up to 400 times their weight in water and acting as a reservoir during dry periods. There is also a lot of interest lately in root stimulating products that add mycorrhizae to the soil.

Caring for your new plants: All coleus are tender and cannot survive freezing temperatures. It is best not to place them outside for the season until they have been hardened off and the average overnight low temperatures stay above 60 degrees. This might be a few weeks after your last average spring frost date. Even if there is no frost, nights in the 40's can still damage your Coleus! Planting your Coleus outdoors while the nights are still cool may result in slow or stunted growth and an increased chance of fungal diseases caused by cool, wet soil. Planting your coleus out into sun, wind, and/or hot temperatures before they have been properly acclimated can harm them and cause wilting and leaf damage. Your new plants from Rosy Dawn Gardens have been greenhouse grown, so it is important that they be "hardened off" before you place them outdoors. Direct sun and wind can be very damaging to tender young Coleus, so begin by potting them up and allowing them to develop a good root system. This step is especially important if you will ultimately be planting your Coleus directly into the ground. The larger their root system is at planting the better they will do.

After potting your Coleus, place them outdoors everyday for 3-4 hours in full or partial shade in a wind-sheltered location. Gradually increase the time outdoors every day, and by the end of the first week you should be able to gradually begin to acclimate them to their permanent location (if it differs from where they have been previously held). A temporary windbreak or sun protection should be offered for a time if the Coleus are planted in an exposed location. Regular daily watering of exposed coleus is crucial to their survival.

Close attention should still be given to the amount of heat, cold, sun, and wind your Coleus receive for at least two more weeks after hardening off and protection should be available at any time during the summer if inclement weather or sudden cold snaps threaten your plants.

Watering, Fertilizing and Pruning: Coleus prefer their roots to be in soil that is evenly moist but not soggy. The more your coleus are exposed to sun and wind, the more often they will need to be watered. Daily or twice-daily watering may be necessary, especially as the coleus mature and develop a large leaf canopy. Coleus that have wilted will usually respond quickly when watered, but coleus that have been repeatedly allowed to wilt will quickly show signs of wear and tear that make them less attractive: crispy edges, dry brown spots on the leaves, bleaching, and dull color. Mulch is recommended for Coleus grown in the ground in hot areas. Drip irrigation is great for plants grown in pots or in the ground because it keeps the water off the leaves. Watering is best done in the early morning so the leaves have time to dry before the sun hits them. Coleus leaves should always be dry by the time darkness falls to decrease the chance of fungal disease occurring.

Coleus do not show their best color when over fertilized, so fertilize at half strength on a regular basis, or use a time release fertilizer (recommended).
Pinching the growing tips of your coleus when they are young will increase branching and make your plant more bushy. Some coleus plants will bloom, and the blooms may be pinched off or allowed to develop according to your personal preference. It doesn't hurt coleus to be pinched and pruned. In fact, it is often necessary to prune coleus in mid-summer to help the plant keep its shape and freshen its appearance. A plant that is allowed to overgrow may cause its pot to topple or branches may snap under their own weight.

Sun or Shade? The amount of light your Coleus plants receive will affect their coloration, so the same variety of Coleus grown in two different locations in your yard may vary in appearance. Most Coleus can take some sun, and several can tolerate full sun if properly acclimated. Coleus grown in full sun will create more pigmentation to protect itself from the sun. For example, bright yellow or chartreuse may become a dark gold or green. Oranges may become red. Reds may become burgundy. Dark colors may dominate lighter colors on the leaf. Results also vary according to region. Full sun for our friends in Texas or Florida is much stronger than full sun for us here in Michigan! The most important thing to remember when growing coleus in full sun is that they need proper preparation and consistent watering to look their best.

Coleus have historically been considered a shade plant, and Coleus do grow well in dappled or partial shade, but no coleus will do well in deep shade. Coleus are not mushrooms and a certain amount of light is necessary to maintain the proper level of pigment in the leaves. The deeper the shade, the more washed out the colors will be. Deep shade may also cause lanky, contorted growth as the plant stretches towards light, and damp soil may cause disease.

The plants that are photographed for the Rosy Dawn Garden catalog are mature plants that have been grown in bright morning light with protection from the afternoon sun.

Pest and Diseases: The most common pest of coleus are mealybugs, which look like little tufts of white fuzz on the stems, leaves, and leaf axils. They are very slow moving and can be eliminated by a cotton swab dipped in alcohol or by an insecticide. Another pest you might encounter is whitefly, which are very tiny and fly out from under the leaves, especially when the plant is disturbed. Whiteflies are attracted to the color yellow, and a yellow sticky-trap (available in garden centers) can sometimes be used to control them without pesticides. Aphids can also attack coleus and can be treated by spraying them with water, wiping them off the coleus or spraying with an insecticide. Spider Mites can be identified by the tiny webs that form on the underside of leaves and the presence of poppy-seed sized red mites. Spider mites flourish when the humidity is low, and can be controlled by careful monitoring and cleaning of the leaves, increasing the humidity near the plants, or spraying the leaves with an insecticide. Fungus gnats are tiny black flies that hover near the soil. Fungus gnats are especially attracted to plants that have overly wet soil in an area of poor air circulation. They can be controlled by correcting any watering or air circulation issues that might exist and by adding a 1/4 inch layer of fine gravel (even aquarium gravel or parakeet grit!) to the top of the soil to prevent the adults from laying eggs. Slugs can damage coleus by eating the leaves and stems. Commercial slug bait or making your own slug traps using beer are both options. A circle of diatomaceous earth powder around your plants can make a deadly barrier for slugs to cross as it will puncture their skin and cause them to dehydrate. Copper barriers will also create an uncomfortable situation for slugs.

If you don't want to spray for pests and don't have any worries about children or pets ingesting your plants you can use a systemic insecticide that you put in the soil (as directed) and it will help with control of pests for several weeks or months at a time. This works best with coleus grown in pots. Insecticide sprays may include insecticidal soap, pyrethrum sprays, or all-purpose houseplant or ornamental sprays available at garden centers. At Rosy Dawn Gardens we find that lady beetles, lacewings, and predatory wasps do a great job of policing our plants when they summer outdoors. We only need to use pesticides when the plants are in the greenhouse.

Coleus, when provided with a good location and the correct amount of light, water, warmth, and air circulation, are quite resistant to disease. Removing dead or yellowed leaves from the area around the coleus will help as well. Soggy soil and cool temperatures are a combination that invite fungal diseases such as botrytis, stem rot, and powdery mildew. Avoid overhead watering if possible and try to get the water directly to the soil. Water early in the day so the leaves are dry by evening. If you notice signs of fungal disease such as curling leaves, excessive leaf drop, moldy patches, or black spots on the leaves begin by correcting any problems with the basic requirements of the plant, such as watering, cold temperatures, and lack of air circulation. If the problem persists, contact a local garden center for information on anti-fungal products that are safe for coleus.

Coleus as Houseplants: Coleus can be grown as houseplants, but particular attention must be given to light, water, humidity, and pest control. Any coleus can be kept in the house, so you are limited only by the amount of brightly lit space you have available. You should turn your plant regularly when grown in a window so the plant doesn't lean too much in one direction. If you don't have a window that allows bright light you might want to consider supplementing with florescent fixtures. Many people grow their coleus under florescent grow-lights or use them as a supplement to natural light.

Like most houseplants, coleus should be watered carefully. They don't want to be soggy but they don't want to be too dry either. Care must be taken not to over water indoor coleus, nor should they be allowed to get so dry that the plants wilt. They like a higher level of humidity than most houses have so they benefit from daily misting early in the day.

Since there are no natural predators in the house such as ladybugs or lacewings you will have to be diligent about checking for pests regularly (see above). If you use a pesticide, make sure it is approved for indoor use. Insecticidal soap is often a good choice. Read all directions carefully.
Coleus will sometimes become lanky when grown indoors, so don't be afraid to pinch and prune your indoor coleus to keep it tidy and prevent flowering. Another thing to keep in mind is that coleus sometimes have different coloration in the winter months, especially when kept in a house. Usually they return to their original coloration when the days lengthen or they are moved outdoors for the summer.