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If you want to cut corners to prevent an expensive gardening endeavor, seed starting is the way. The best part is you can save loads of money. Still, not all plants can start from seed; you might need to invest in seedling plants.
But if you have limited time and space, Coleus seeds outdoors is the way to go. The best is you only need to sow them once and will have an endless supply of plants early in the season. So, gather your supplies of soilless seed starting mix, containers, and seeds so we can get started.
Plant Name: Plectranthus scutellarioides with previous names Solenostemon scutellarioides and Coleus scutellarioides
Other Name: Coleus
Plant Type: Annual or Perennial Herb or Shrub
Native Areas: Africa, Asia, and India
Light Requirements: Full Shade Plant
Watering: Water When the Top Inch of Soil Dry
Fertilizer: Liquid Fertilizer
Growth: 36-inches Tall and Wide
Propagation: Stem Cuttings
Soil Type: Well Drained Loose Soil
Temperature: Hot, Humid Conditions
Toxicity: Toxic To Animals
USDA Hardiness Zones: 10 to 11
More About Coleus Plants
Coleus plants @flickr
Coleus plants belong to a problematic group and can be very confusing as you can find different species. Therefore, while it has undergone many scientific names, we will keep things simple, calling it by the common name Coleus.
The Coleus plants have multi-colored foliage comprised of 294 Coleus species, with 72 Plectranthus species and up to 42 Equilabium species. The Coleus genus can grow as an annual or perennial herb or shrub; some have succulent leaves and stems.
You find the leaves whorled or growing on opposite sides. The inflorescence varies from multi-flower buds, branched, lax, simple, to single. At times the flowers have a pedicel or are sessile. You find the flowers in a tubular shape or with a tubular calyx that is curved or straight.
As there are so many Coleus plants, we have compiled a list to check out later that will grow best from seeds in your garden. Another notable thing is growing Coleus from seed is excellent as a perennial if you live in warmer zones.
But in most gardens, it grows as an annual bedding plant or as a potted plant, as not all are frost tolerant.
When To Plant This Annual Flowering Plant
Coleus seeds can take some time to germinate and also is slow growing. Hence, it helps to start your plants as early as eight to twelve weeks before the last frost. Thus, the earlier you start, the larger your outdoor plants will be.
Lastly, it is essential not to transplant them before the frost has passed.
Another notable thing is that your plants need a lot of tender loving care and watering. Still, you need not transplant your Coleus potted plants, as they make gorgeous houseplants.
Planting Coleus Seeds Indoors
When sowing seed indoors for planting potted plants, you can do this about eight weeks before the last frost date. The critical thing to remember is that the Coleus seeds are fine, and it helps to plant the tiny seeds in flats or other containers.
You can find several options, like investing in a seed starting kit. For the seed starting mix, it helps to choose a planting medium like African Violets or use light-rich soil with some topsoil sifted through a screen wire.
Sowing seeds indoors must be shallow in the soil and not covered with the soil.
Keep the soil moist, and if you have a heat mat, your Coleus will love it as it helps germinate. Keep the soil temperatures around 65°F to 85°F.
Do not cover the seeds; you will notice germination in 12 to 21 days.
Once the seedlings emerge, it helps to provide them with a lot of light on a sunny windowsill. Or you can use fluorescent plant lights 16 hours a day and off for 8 hours at night.
Also, raise the grow lights as your plants grow taller, and using incandescent bulbs does not work as it gets too hot. We recommend not leaving the lights on for 24 hours as seedlings need a dark period to grow.
Then thin out one seedling per cell when it has two sets of leaves.
Only feed your seedlings after four weeks using a half-strength complete indoor houseplant food.
Still, before transplanting your seedlings, you will need to harden them to accustomed young plants to the outdoors.
You can do this by keeping them sheltered for about a week. Protect your young plants from the hot sunlight and wind at first.
Also, cover containers at night if frost is present or bring the containers indoors.
Transplant Hardened Off Seedlings
Once your Coleus seedlings are hardened-off, you can find the perfect spot in the garden in full sun to part shade. Provide your Coleus with some organic soil that drains well.
Prepare a plant bed by turning the soil over to a depth of eight inches to transplant Coleus.
Use a rake to remove clumps, debris, grass, stones, and other plants as weeds compete for water. After planting, you can use organic matter like compost or a top dress to amend the soil.
You can also add organic mulch after planting to retain soil moisture.
Place your Coleus plant about 12 inches apart and dig a hole for each plant big enough to accommodate the root ball.
Place the root ball level with the surrounding soil and backfill while pressing down firmly.
Water well to form puddles in the saucer created, leaving it to settle and drive out the air pockets.
Place a plant tag as your location marker
Caring For Coleus
The Coleus is a rewarding yet undemanding plant that forms a scrambling ground cover. Depending on the species you have, it can thrive in full sun to partial shade. Some species can take mild frost and grow well in potting soil in containers.
Keep Soil Moist Coleus Seed
The best soil mix is a loose yet well draining one. Before planting potted plants, it helps to do soil amendments using organic material, compost, or perlite.
You can use a quality potting mix for potted plants in hanging baskets and provide your plant with a container with drainage holes.
Growing Coleus from seed in a container, use a quality potting mix that is slightly acidic to neutral.
We also recommend a soil test to ensure you provide the right soil for your plant’s needs.
Lighting Needs For Coleus Seed
When starting your Coleus seeds, you need to give them bright light to grow. Yet, once your smaller plants are planted outdoors and mature, it prefers full to part shade instead of full sun. Still, it does depend on the variety you grow.
The problem is the sun can scorch the colorful foliage. So, provide some filtered morning sun with shade in the afternoon. Grown container plants indoors receive enough bright indirect light in summer but will need dappled sunlight in winter.
Watering Coleus Plants
Your plant prefers the soil to be moist but not soggy. This is because the leaves turn brown around the edges during the growing season, with dry spells. Still, allowing the soil to dry out between watering would be best. So, only water when the top inch feels dry to the touch.
To help retain soil moisture, it helps to add mulch but never use cedar as it is toxic to your plant. Neither should the mulch touch the stem. For container plants, you may need to water often during warm weather.
Temperature and Humidity
Coleus thrives in warm, humid environments, but a hint of frost can kill it. Bring containers indoors to protect your plants from the chilly nights when temperatures drop to 50°F. Another recommendation is to take cuttings for Coleus propagation before the weather turns cold.
Furthermore, keep your smaller plants indoors, away from cold drafts or air conditioners. With arid climates, it helps to invest in a humidifier or keep them in the bathroom. When spring arrives, Coleus indoors can be taken outside when the temperature reaches 70°F.
If your plant grows in rich soil, you need not feed your plants. But for poor soil, it helps to add a slow-release fertilizer/liquid houseplant fertilizer/granular fertilizer. Apply a light fertilizer for the best foliage color. You can feed container-grown Coleus with a liquid fertilizer.
Pruning Your Plant
It helps pinch stem tips when it reaches six inches tall to encourage bushy growth. When you pinch flower stalks under the buds, it spends more energy on developing leaves. When not pruned, it grows a vigorous-looking stem tip that is leggy and losing shape.
When this happens, provide your plants with more sunlight.
How to Propagate Coleus?
You can propagate Coleus cuttings with the following steps:
First, use sterile sharp scissors to take stem cuttings with a length of six inches beneath a leaf node from a parent plant and remove all the lower leaves.
Dip the cut end into rooting hormone and plant into moist soil while covering the exposed leaf nodes.
Place a plastic bag over the container but prevent it from touching the foliage or the plant crown.
Place your plant in bright light in a warm location until the roots develop. It can take up to three weeks.
Once you notice new growth with root development, you can remove the covering and keep it in a bright warm spot.
Common Pests and Diseases
These plants respond well to living outdoors but can become bothered by rabbits and groundhogs. Also, keep an eye on aphids, whiteflies, slugs, spider mites, and mealybugs. When your plants are bothered by pests indoors, remove your infected plants to prevent them from spreading.
The other concern is overwatering, which can encourage root rots and mildew.
Coleus Cultivars You Can Grow From Seeds
As mentioned, you can find different cultivars to grow Coleus from seed. Here are some of our favorites.
The Campfire has a compact growth with teethed velvety oval leaves in an orange-red to copper color. The foliage remains vibrant, whether grown in part shade to full sun. It makes for a fine house plant.
Dragon Heart adds color and patterns grown in the shade of the full sun. It is a high-impact plant made for large pots or grown in landscaping.
It is an eye-catching cultivar with a vivid pink leaf with green margins and cream flecks with deep red veins. The plant reaches 22 inches tall and spreads to 22 inches.
Rustic Orange can grow up to 24 inches tall, spreading up to 18 inches. It has vibrant orange foliage made for garden beds to borders.
ColorBlaze Golden Dreams
The plant stands up to 36 inches tall and wide when planted in full sun or shady locations. It is an easy-to-grow annual to add foliage interest to your garden.
ColorBlaze Wicked Witch
The Wicked Witch is an evergreen with chocolate burgundy foliage with ruffled edges. It also grows 36 inches tall and wide.
The Ridiculous is another exceptional cultivar as the plants maintain the colorful foliage in certain regions throughout the year. The red foliage makes for a statement indoors and outside.
coleus chocolate mint @flickr
The plant has deep burgundy foliage with serrated leaves and bright green edges. The mature height is 20 inches tall and spreads up to 14 inches. It is a bushy plant with a mounding growth habit.
The midnight-purple foliage and a tinge of red make it beautiful with compact growth. It has deeply lobed leaves with a velvet appearance and reaches 12 inches tall. Depending on the light, it can come over as a dark red to purple color.
The plant does not get its interesting name for anything. The foliage is burgundy to lime green with prominent veins to give it a stunning appearance.
The Wizard Scarlet grows compact foliage with an upright growth habit. A standout is the red velvet leaves which look fabulous in hanging baskets and planted in the garden.
Chocolate Covered Cherry
The mahogany, green, and red colors make a statement on the Chocolate Covered Cherry Coleus. The leaves have a bold shade to add color to any living space.
Kong Red Coleus
The plant has large leaves with unique patterns and an upright mound-growing habit. The foliage varies in color from dark red to green.
The Wizard Mosaic grows serrated pointy leaves, remaining light green with a ruby-red varigation.
The foliage of the Kong Rose is red with green edges, and it is a fast-growing cultivar that prefers shade to direct light.
coleus electric lime @flickr
Bring some vibrant color to your summer garden by planting the Electric Lime. The foliage displays a bright lime-lemon hue to lighten up any shaded spot in the garden.
Wizard Velvet Red
These Coleus seedlings emerge with deep red velvety foliage with green ribboned edges on shaded borders.
The plant also boasts larger leaves in pink and magenta with green. So, it makes for a gorgeous display of color indoors or in landscaping.
coleus trusty rusty @flickr
The serrated leaves of the Trusty Rusty are outlined in golden yellow on the background of the copper leaf color.
Who needs flowers in the garden if you can grow the El Brighto with the purple and red centers on the foliage?
Bring the Limelight into your garden with its bright neon lime-green foliage. It grows best in containers and the garden.
Investing in Coleus seeds is affordable, but if you prefer not to spend your time accustoming young plants for outside, you can also buy Coleus seedlings. It remains a favorite annual to perrenial to grow.
Grow it as a perennial border to provide color year-round. Or grow them as an annual to change up the colors. These plants are ideal for mass planting in shady spots to make a bare spot look more vibrant.
The colorful foliage adds color and texture to create a focal point in the garden. Alternatively, you can grow them in containers indoors. Or place the pots on a patio but remember to bring smaller plants indoors when the temperatures drop.
Now, if you wonder where to purchase seeds, you need not look far, as Plantly has a selection to browse through. So what are you waiting for? Start adding some year-long color to your garden.
Whether you want to buy, sell, or simply reach out to other plant enthusiasts, Plantly is the right place to be!