The colorful foliage of coleus plants can be used to brighten any corner of the flower garden, from the shady areas to sunny spots. No other garden plants are as easy to root as coleus plants. Even single leaves can be used to root and grow whole new plants. Coleuses root quickly and grow to full size rapidly given good soil, moisture, and warm conditions.
Rooting coleuses is a great way to save particularly liked plants over the winter months to fill the garden with them once warm weather makes its appearance again. It is also a good way to create multiple plants for filling in bare spots in the garden. Supplies needed for rooting coleuses include; containers for growing the plants in - these need to be at least 4 inches deep and have bottom holes to drain through, sterile potting soil, clean coarse sand, and watering trays. Without a greenhouse or very sunny window sill, a grow light set up will be needed. Coleuses need a warm area to grow well with temperatures in the mid 70's or higher. For plants that will be held over the winter months it is necessary to use at least 4 inch pots for each cutting so it has room to grow without crowding the roots. Summertime cuttings grown for extra plants, can be crowded closer together as they will be set out sooner.
Coleus cuttings will root easily in just plain water but plants rooted this way will have very tender roots and will be shocked when set out in the soil setting the new plants back. A better plan is to root the cuttings in a soil mixture so they form hardier roots. The best soil mixture to use is one made up of equal parts potting soil and coarse sand. It is important that the soil be sterile so no plant diseases or fungi will attack the cuttings. Don't use beach sand as it contains salts and coleuses cannot stand salt. Don't add any fertilizers to the rooting mixture because the young tender roots are easily burned by it and the young plants will grow too fast if the soil is too rich.
Make up the soil/sand mixture and fill the containers with it, tapping it down well so the soil will not settle when the cuttings are watered. It is best to water the coleus cuttings from the bottom to encourage the roots to develop deeply. If using plant containers that have been previously used, be sure to clean and disinfect them well to stop the spread of any plant diseases. After rinsing the containers off, soak them in a 10% bleach solution for a couple of hours then rinse again and let dry before filling them.
Collect the coleus cuttings by pinching off sections of the growing plants. The cuttings only need to be an inch long with each one having at least one growth bud which are located where a leaf joins the stem and at the growing tip of each branch. Don't use the flowering tips of coleus plants. Whole sections of the plants can be cut off and then taken to the work area to be divided into smaller cuttings. If the coleus cuttings cannot be placed in the soil right away, it is important to place them in a container of water so they do not wilt. Trim any excess leaves from each cutting leaving only one near the top end. The leaves will only act to lose water at this point causing the cutting to dry out. Push the cutting into the soil/sand mixture and firm the soil around it well. The coleus cuttings need to be a couple of inches apart if several are planted in a single container. It is not necessary to use rooting hormone on coleus cuttings.
Place the potted up cuttings in a watering tray and water them well from the top to settle the soil around the cuttings. After this initial watering it is best to water the growing cuttings from the bottom. Set the containers and trays in a brightly lit area such as a south facing window or under a grow light. Make sure the grow light is no more than 4 inches from the tops of the coleus cuttings. If the cuttings are going to grow in a dry environment like the inside of most houses during the winter, it is best to cover them with some sort of clear plastic cover to hold the moisture in until the roots have developed. Cut off tops of plastic jugs or the plastic boxes used to hold berries, both make good mini greenhouse covers for the growing cuttings.
Watch for any signs of new growth on the cuttings and keep them well watered with about an inch of water in the treys. Once the buds start to leaf out, the plastic covers can be removed for half a day to harden the plants off. Start letting the coleus plants dry out between waterings but don't let them wilt. If the stems grow too spindly this is a sign they are not getting enough light. Pinch out the tips of the growing plants to encourage branching to make them bushy. When the weather warms in your gardening zone and all dangers of frosts are gone, the new coleus plants can be gotten ready for setting out by hardening them off. Over a period of 4 days take the plants outside for gradually longer periods of time each day. Start by placing them in a shady, sheltered area for a couple of hours and be sure to keep them well watered. Plant the coleuses in good rich soil and water them with some water soluble fertilizer to get them over being transplanted.