How to Grow Coleus from Seed: A Complete Guide

Key Takeaways

Have you ever wanted to grow your own rainbow in your garden? No, I’m not talking about planting skittles or chasing leprechauns. I’m talking about growing coleus, one of the most colorful and versatile plants you can find.

Coleus is a genus of flowering plants in the mint family that are native to tropical and subtropical regions. They are grown for their colorful and variegated foliage that can range from green, yellow, pink, red, purple, and orange. They are also known as painted nettle or flame nettle.

Coleus is a great plant for beginners and experts alike, as it is easy to grow, propagate, and care for. It can add a splash of color and texture to any garden, patio, or indoor space. It can also attract pollinators, repel pests, and improve air quality.

In this article, you will learn how to grow coleus from seeds step by step, from sowing to harvesting. You will also learn how to choose the best varieties and colors of coleus for your needs, how to transplant, prune, and pinch your plants for optimal growth and shape, how to overwinter your plants indoors or outdoors, and how to deal with common pests and diseases that may affect your plants.

How to Propagate Coleus from Seeds

Propagating coleus from seeds is a fun and rewarding way to grow new plants with unique colors and patterns. You can also save money by buying seeds instead of plants, and have more control over the quality and quantity of your plants.

However, propagating coleus from seeds also has some drawbacks. It may take longer for your plants to mature and bloom than if you use cuttings or division. You may also get some unexpected results in terms of color and shape, as coleus seeds are often hybrids that do not breed true to their parents.

To propagate coleus from seeds, you will need the following materials and tools:

• Coleus seeds: You can buy coleus seeds online or at your local nursery or garden center. You can also collect your own seeds from your existing plants if they have flowered and produced seed pods. However, keep in mind that the seeds may not be identical to their parents.
• Potting soil or seed starting mix: You will need a light, well-draining, and sterile medium for sowing your seeds. You can use a commercial potting soil or seed starting mix that contains peat moss, perlite, vermiculite, compost, etc. You can also make your own mix by combining equal parts of peat moss and perlite or vermiculite.
• Flat or container: You will need a shallow tray or pot with drainage holes that is large enough to hold your seeds. You can use a plastic flat or container that is designed for starting seeds or any other container that you have at home such as an egg carton, a yogurt cup, a milk carton, etc.
• Labels: You will need some labels to mark your flat or container with the name and date of sowing your seeds. You can use wooden sticks, plastic tags, paper clips, etc.
• Dome lid or plastic wrap: You will need a clear cover to create a mini greenhouse effect for your seeds. You can use a dome lid that fits your flat or container or simply use some plastic wrap that you secure with rubber bands or tape.
• Heating pad or seed-starting mat or warm window sill: You will need a source of heat to provide the optimal temperature for your seeds to germinate. You can use an electric heating pad or seed-starting mat that you place under your flat or container and set at 70-75ºF (21-24ºC). You can also use a warm window sill that receives bright but indirect light.

To sow your coleus seeds indoors follow these steps:

1. Fill your flat or container with potting soil or seed starting mix up to an inch below the rim. Level and firm the surface with your hand or a spatula. Moisten the soil or mix with water until it is damp but not soggy.
2. Sow your coleus seeds on the surface of the soil or mix, as they need light to germinate. Do not cover them with soil or mix. You can sprinkle some fine sand or vermiculite over them to help retain moisture. You can sow your seeds densely or thinly depending on how many plants you want to grow. Leave some space between the seeds for air circulation.
3. Label your flat or container with the name and date of sowing your seeds. Cover it with a dome lid or plastic wrap to create a mini greenhouse effect.
4. Place your flat or container on a heating pad or seed-starting mat set at 70-75ºF (21-24ºC), or on a warm window sill that receives bright but indirect light. Avoid direct sunlight as it may scorch your seeds or seedlings.
5. Keep the soil or mix moist but not soggy by misting it lightly with water every day or as needed. Do not overwater as it may cause damping off or fungal diseases.
6. Check your flat or container daily for signs of germination. Coleus seeds usually germinate within 10-14 days after sowing.

How to Care for Coleus Seedlings

Once your seeds have sprouted, you will need to transplant them into individual pots or larger containers once they have developed their first true leaves (the second pair of leaves after the cotyledons). You will also need to harden them off before moving them outdoors permanently.

To transplant your coleus seedlings, you will need the following materials and tools:

• Individual pots or larger containers: You will need pots or containers with drainage holes that are large enough to hold your seedlings. You can use plastic, clay, metal, wood, or any other material that you prefer. The size of the pots or containers depends on how big you want your plants to grow. Generally, you can use 4-inch pots for dwarf varieties, 6-inch pots for medium varieties, and 8-inch pots for tall varieties.
• Potting soil or seed starting mix: You will need the same medium that you used for sowing your seeds or a similar one that is light, well-draining, and sterile. You can also use a potting mix that contains perlite, vermiculite, or peat moss to improve drainage and aeration.
• Labels: You will need some labels to mark your pots or containers with the name and date of transplanting your seedlings.

To transplant your coleus seedlings follow these steps:

1. Carefully remove your seedlings from the flat or container by gently loosening the soil or mix around them. Try not to damage the roots or stems of your seedlings.
2. Make a hole in the center of each pot or container that is large enough to accommodate the root ball of your seedling. Place your seedling in the hole and gently press the soil or mix around it. Make sure the soil or mix level is the same as it was in the flat or container.
3. Water your transplanted seedlings well and label them with the name and date of transplanting. Place them in a bright but shaded spot until they are established. Avoid direct sunlight as it may burn your seedlings.
4. Keep the soil or mix moist but not wet by watering your seedlings regularly or as needed. Do not overwater as it may cause root rot or fungal diseases.

To harden off your coleus seedlings, you will need to gradually acclimate them to the outdoor conditions before planting them in their final location. This will help them avoid shock and stress from sudden changes in temperature, light, wind, etc.

To harden off your coleus seedlings follow these steps:

1. Start hardening off your seedlings about two weeks before the last frost date in your area. You can check the frost dates for your location online or consult your local nursery or extension service.
2. Choose a sheltered spot outdoors that receives partial shade and protection from strong winds. You can use a cold frame, a cloche, a row cover, or a shade cloth to provide some cover for your seedlings.
3. Bring your seedlings outdoors for a few hours each day, increasing the duration and exposure gradually over time. Start with two hours on the first day, then four hours on the second day, then six hours on the third day, and so on until they are outside for the whole day.
4. Monitor your seedlings closely for signs of stress or damage, such as wilting, curling, yellowing, browning, etc. If you notice any problems, bring them back indoors and reduce the duration and exposure until they recover.

How to Choose Coleus Varieties and Colors

Coleus comes in a wide range of varieties and colors that can create stunning effects in your garden or indoor space. You can choose coleus varieties and colors that match or contrast with each other or with other plants in your landscape. Some factors to consider when choosing coleus varieties and colors are:

• Size: Coleus can vary in size from dwarf (6-12 inches) to tall (24-36 inches) depending on the variety. You can choose coleus varieties that fit your space and design goals. For example, you can use dwarf varieties for edging, borders, containers, or hanging baskets; medium varieties for mass planting, beds, or borders; and tall varieties for background, focal points, or specimen plants.
• Shape: Coleus can have different shapes of leaves, such as round, oval, heart-shaped, lance-shaped, scalloped, serrated, lobed, etc. You can choose coleus varieties that have interesting and diverse shapes of leaves that add texture and dimension to your garden or indoor space.
• Texture: Coleus can have different textures of leaves, such as smooth, velvety, hairy, glossy, matte, etc. You can choose coleus varieties that have different textures of leaves that create contrast and interest in your garden or indoor space.
• Pattern: Coleus can have different patterns of colors on their leaves, such as solid, speckled, splashed, striped, edged, blotched, etc. You can choose coleus varieties that have different patterns of colors that create stunning and unique effects in your garden or indoor space.
• Color combination: Coleus can have different combinations of colors on their leaves, such as green and yellow, pink and purple, red and orange, etc. You can choose coleus varieties that have different combinations of colors that match or contrast with each other or with other plants in your landscape.
• Sun tolerance: Coleus can have different levels of sun tolerance depending on the variety. Some coleus varieties can tolerate full sun or partial sun, while others prefer shade or partial shade. You can choose coleus varieties that suit the light conditions of your location. Generally, coleus varieties with darker colors are more sun tolerant than those with lighter colors.
• Bloom time: Coleus can bloom at different times depending on the variety. Some coleus varieties bloom in spring or summer, while others bloom in fall or winter. You can choose coleus varieties that bloom at the time you prefer. However, most gardeners prefer to pinch off the flowers of coleus as they are not very showy and may detract from the beauty of the foliage.

Here are some examples of popular coleus varieties and colors that you can try:

How to Prune and Pinch Coleus Plants

Pruning and pinching are essential practices for growing healthy and beautiful coleus plants. Pruning involves cutting off the stems or branches of your plants with a sharp knife or scissors. Pinching involves removing the tips or buds of your plants with your fingers or nails.

Pruning and pinching your coleus plants can help you achieve the following benefits:

• Maintain their shape and size: Pruning and pinching can help you control the height and width of your plants and prevent them from becoming leggy or spindly. You can also prune and pinch your plants to create different shapes such as round, square, pyramid, etc.
• Encourage bushiness and branching: Pruning and pinching can stimulate new growth and branching from the nodes (the points where leaves attach to the stems) of your plants. This can make your plants fuller and denser with more foliage.
• Prevent flowering: Pruning and pinching can prevent or delay the flowering of your plants. This can help you focus on the foliage rather than the flowers of your plants. It can also prevent your plants from producing seeds that may not be true to their parents.

The best time to prune and pinch your coleus plants is in spring or summer when they are actively growing. You can also prune and pinch your plants throughout the growing season as needed.

The best place to prune and pinch your coleus plants is just above a node where a pair of leaves emerges from the stem. This will encourage new growth from that node.

The frequency and amount of pruning and pinching depend on the variety and growth rate of your plants. Generally, you should prune and pinch your plants every two to four weeks or whenever they become too tall or wide for your liking. You should remove about one-third to one-half of the length of each stem or branch.

To prune and pinch your coleus plants follow these steps:

1. Choose a sharp knife or scissors that are clean and disinfected. You can use rubbing alcohol or bleach to sanitize your tools.
2. Cut or pinch off the tip or bud of each stem or branch just above a node where a pair of leaves emerges. Make sure you leave at least two pairs of leaves on each stem or branch.
3. Discard or compost the cuttings or use them to propagate new plants by placing them in water or soil.
4. Water your pruned or pinched plants well and apply some organic fertilizer if needed.

How to Overwinter Coleus Plants

Overwintering is the process of protecting your plants from cold temperatures and frost during the winter months. Overwintering your coleus plants can help you preserve them for the next growing season and enjoy their colorful foliage year-round.

The best way to overwinter your coleus plants depends on the climate zone you live in. Coleus is a tender perennial that cannot survive freezing temperatures below 32ºF (0ºC). Therefore, if you live in a zone where the temperature drops below this point, you will need to overwinter your plants indoors. If you live in a zone where the temperature stays above this point, you may be able to overwinter your plants outdoors with some protection.

To overwinter your coleus plants indoors, you will need to do the following steps:

1. Choose healthy and disease-free plants that you want to overwinter. You can either overwinter the whole plants or take cuttings from them.
2. Before the first frost, dig up your plants from the ground or remove them from their containers. Shake off the excess soil and trim off any damaged or diseased parts. You can also prune and pinch your plants to reduce their size and shape.
3. Repot your plants or cuttings in fresh potting soil or mix and water them well. Label them with the name and date of overwintering.
4. Place your plants or cuttings in a bright and cool spot indoors that receives at least six hours of indirect light per day. You can use artificial lights such as fluorescent or LED lamps to supplement the natural light. Avoid direct sunlight as it may scorch your plants or cuttings.
5. Keep the soil or mix moist but not wet by watering your plants or cuttings sparingly or as needed. Do not overwater as it may cause root rot or fungal diseases.
6. Monitor your plants or cuttings for signs of pests or diseases, such as aphids, spider mites, mealybugs, whiteflies, powdery mildew, etc. If you notice any problems, treat them promptly with organic or chemical methods.

To overwinter your coleus plants outdoors, you will need to do the following steps:

1. Choose healthy and disease-free plants that you want to overwinter. You can either overwinter the whole plants or take cuttings from them.
2. Before the first frost, mulch your plants with a thick layer of organic material such as straw, leaves, bark, etc. to protect their roots from cold and frost. You can also cover your plants with a row cover, a cloche, a cold frame, or a frost blanket to provide some insulation and ventilation.
3. Water your plants sparingly or as needed during the winter months. Do not overwater as it may cause root rot or fungal diseases.
4. Monitor your plants for signs of pests or diseases, such as aphids, spider mites, mealybugs, whiteflies, powdery mildew, etc. If you notice any problems, treat them promptly with organic or chemical methods.

How to Deal with Coleus Pests and Diseases

Coleus is generally a low-maintenance and pest-resistant plant that does not require much attention. However, it may occasionally suffer from some pests and diseases that can damage its foliage and health. Here are some of the most common problems that may affect your coleus plants and how to deal with them:

• Aphids: These are small, soft-bodied insects that suck the sap from the leaves and stems of your plants. They can cause yellowing, curling, wilting, and distortion of the foliage. They can also transmit viral diseases and secrete honeydew that attracts ants and fungal growth.
  • To prevent aphids, keep your plants healthy and stress-free by providing adequate water, light, nutrients, and air circulation. Avoid over-fertilizing your plants as this may make them more susceptible to aphids.
  • To treat aphids, spray your plants with a strong jet of water to dislodge them from the foliage. You can also use organic methods such as insecticidal soap, neem oil, or horticultural oil to kill them on contact. Alternatively, you can use chemical methods such as systemic insecticides that are absorbed by the plant and kill the aphids from within.
• Spider mites: These are tiny arachnids that feed on the chlorophyll of the leaves of your plants. They can cause speckling, bronzing, webbing, and defoliation of the foliage. They thrive in hot and dry conditions and can multiply rapidly.
  • To prevent spider mites, keep your plants moist and cool by misting them regularly or placing them in a humidifier. Avoid exposing your plants to extreme heat or drought stress as this may make them more vulnerable to spider mites.
  • To treat spider mites, spray your plants with a strong jet of water to remove them from the foliage. You can also use organic methods such as insecticidal soap, neem oil, or horticultural oil to kill them on contact. Alternatively, you can use chemical methods such as miticides that are specifically designed to control spider mites.

• Mealybugs: These are small, white, cottony insects that suck the sap from the leaves and stems of your plants. They can cause yellowing, wilting, and stunting of the growth. They can also secrete honeydew that attracts ants and fungal growth.
  • To prevent mealybugs, keep your plants healthy and stress-free by providing adequate water, light, nutrients, and air circulation. Avoid over-fertilizing your plants as this may make them more attractive to mealybugs.
  • To treat mealybugs, dab them with a cotton swab dipped in rubbing alcohol or spray them with a solution of water and vinegar. You can also use organic methods such as insecticidal soap, neem oil, or horticultural oil to kill them on contact. Alternatively, you can use chemical methods such as systemic insecticides that are absorbed by the plant and kill the mealybugs from within.
• Whiteflies: These are small, white, winged insects that feed on the sap of the leaves of your plants. They can cause yellowing, curling, wilting, and dropping of the foliage. They can also transmit viral diseases and secrete honeydew that attracts ants and fungal growth.
  • To prevent whiteflies, keep your plants healthy and stress-free by providing adequate water, light, nutrients, and air circulation. Avoid over-fertilizing your plants as this may make them more prone to whiteflies.
  • To treat whiteflies, spray your plants with a strong jet of water to knock them off the foliage. You can also use organic methods such as insecticidal soap, neem oil, or horticultural oil to kill them on contact. Alternatively, you can use chemical methods such as systemic insecticides that are absorbed by the plant and kill the whiteflies from within.
• Powdery mildew: This is a fungal disease that causes a white or gray powdery coating on the leaves and stems of your plants. It can reduce the photosynthesis and vigor of your plants. It thrives in humid and shady conditions and can spread by wind or water.
  • To prevent powdery mildew, keep your plants healthy and stress-free by providing adequate water, light, nutrients, and air circulation. Avoid overcrowding your plants as this may reduce air flow and increase humidity. Prune and pinch your plants regularly to remove any infected or dead parts.
  • To treat powdery mildew, spray your plants with a solution of water and baking soda or milk. You can also use organic methods such as neem oil or sulfur to kill the fungus on contact. Alternatively, you can use chemical methods such as fungicides that are specifically designed to control powdery mildew.
• Root rot: This is a fungal disease that causes the roots of your plants to decay and rot. It can cause wilting, yellowing, browning, and death of your plants. It is caused by overwatering or poor drainage of the soil or mix.
  • To prevent root rot, keep your plants healthy and stress-free by providing adequate water, light, nutrients, and air circulation. Avoid overwatering your plants as this may cause soggy or waterlogged soil or mix. Use well-drained and fertile soil or mix for your plants. Add some perlite, vermiculite, or peat moss to improve drainage and aeration.
  • To treat root rot, remove your plants from the ground or their containers and inspect their roots for signs of decay or rot. Cut off any infected or dead parts with a sharp knife or scissors and disinfect the tools with rubbing alcohol or bleach. Repot your plants in fresh potting soil or mix and water them well. Place them in a bright and dry spot until they recover.

Conclusion

Coleus is a wonderful plant that can brighten up your garden or indoor space with its colorful and varied foliage. You can easily grow coleus from seeds by following the steps outlined in this article, from sowing to harvesting. You can also choose from a wide range of coleus varieties and colors that suit your preferences and needs. You can also prune and pinch your plants to maintain their shape and size, encourage bushiness and branching, and prevent flowering. You can also overwinter your plants indoors or outdoors depending on the climate zone you live in. You can also prevent and treat common pests and diseases that may affect your plants, such as aphids, spider mites, mealybugs, whiteflies, powdery mildew, root rot, etc.

Now that you know how to grow coleus from seeds, why not give it a try and see for yourself how easy and rewarding it is? You can also share your results and tips with us in the comments section below. We would love to hear from you! Happy gardening! ????