Coleus are typically a leafy decorative plant that is grown outside to add a burst of color to garden beds but they are also great for growing in pots and do just as well indoors. They are fast growing and can get up to 2’ tall. They are super easy to care for and propagate, and come in a variety of colors and forms. They are usually considered “shade-loving” plants and their vibrant colors tend to fade when exposed to full sun.
Coleus is native to tropical Southeast Asia so it grows best in temperatures between 15-35℃ but can tolerate short periods of time at temperatures as low as 10℃. They can be grown outdoors year-round in zones 10-11 but are usually planted outdoors as annuals. If you live in zone 9 or lower, they can be grown in pots and moved inside when the temperature drops.
Coleus are generally considered full-shade plants but there are new varieties that are more sun tolerant. The vibrant colors tend to fade and get washed-out when exposed to direct sunlight for more than a few hours per day. Generally, their colors are the most vibrant when they receive early morning sunlight and are shaded during the day. When grown indoors, they usually receive enough light as long as they aren’t in a dark corner. For the best display of colors, I would not recommend growing Coleus under high intensity grow lights unless they are placed under a fairly dense canopy and receive only dabbled light.
Coleus prefers a well-drained soil that is kept consistently moist with regular watering. An easy way to know when to water is to put your finger in the soil up to the first knuckle. If the soil feels dry, it is time to water. If it feels cool/moist, leave it for another day or two. After a while, you should get a sense what works in your growing environment. If you notice water pooling on top of the soil for longer than a few seconds while watering, try adding some perlite to the soil mix to improve drainage however most potting soil mixes should work fine. If you are growing Coleus indoors during the winter without supplemental lighting, the growth rate may slow down and watering should be cut down to allow the first inch or so of soil to completely dry out before watering again.
A fertilizer with a high nitrogen content should be diluted to half strength and fed to your Coleus every two weeks. The high nitrogen helps promote the leafy growth and suppresses flowering. Similar to watering, if your Coleus’s growth rate slows down during the winter because you are growing it indoors without supplemental lighting, avoid feeding your Coleus until the growth rate picks back up again in the spring.
Coleus will flower depending on the age of the plant and stress factors such as excess heat, drought, or cold temperatures. When the Coleus flowers, the plant is nearing the end of it’s life cycle and will go to seed and then die shortly after. Although the blooms are beautiful, if you want to keep your plant alive you should pinch the flower buds off as soon as you see them. By doing this, the plant remains in a vegetative state and extends the life of your Coleus. Feeding your plant with a high nitrogen fertilizer helps suppress flowering and reduces the chances that your Coleus will bloom.
- If left on its own, Coleus will grow as a series of tall shoots with little branching. To give your plant a bushier appearance.
- Avoid placing the container directly on the ground where excess water can pool.
- To keep your plant alive, pinch off any blooms as the plant will go to seed if they are left on and eventually die.
- Coleus prefer a humid environment which can be achieve with a humidifier or by misting the leaves with a spray bottle every day.
Coleus are one of the easiest plants to propagate. Cuttings that are 5-6” in length can be taken from larger, mature plants. Cut off the top 5-6” of any shoot just below a leaf node and then remove all but the top few sets of leaves. Cuttings can be rooted directly in soil or in a glass of water and transplanted after roots develop. Cuttings rooted directly in soil are inserted into a potting mix deep enough to bury the first leaf node. Keep the soil moist but not water-logged and in bright, indirect light. After a few weeks, you should start to notice new growth which indicates the cuttings have rooted. To improve the speed and chance of success, you can dip the cut ends into rooting hormone before planting. To root cuttings in water, place the cuttings in a glass of tepid water in bright, indirect light. Change the water every other day to keep it oxygenated and prevent the build-up of algae. Roots should start to develop within a few days but should be left to develop a dense root mass before planting. This typically takes 3-4 weeks.