- Coleus is easy to grow and thrives in both garden beds and containers.
- There are cultivars available for shade, partial shade and full sun.
- They can be started from seed or from cuttings.
- They are grown for their colorful foliage, not their flowers, which can be pinched off.
- Coleus is very cold sensitive and will be the first to be affected by cold overnight lows.
Coleus is a member of the mint family, Lamiaceae. Like other members of the mint family, it has square stems and opposite leaves. This plant is native to the tropics of Asia but grows well in just about any environment.
Unlike most annuals, coleus cultivars are grown for their foliage, not their flowers. They have a wide variety of leaf shapes, sizes and colors.
Coleus plants were once very popular in Victorian-era gardens but are now making a comeback as new cultivars are being developed not only for new foliage patterns but also for different growing conditions.
Historically, Coleus were shade-loving plants and would not tolerate full sun but some new cultivars are sun tolerant. Plants grow between 6 and 36 inches tall and often nearly as wide as they are tall. Various combinations of green, yellow, pink, red and maroon are common foliage colors.
Annual coleus cultivars are evaluated as part of the U of M flower trials and research. Located at the WCROC in Morris, MN, the Horticulture Display Garden serves as an All-America Selections (AAS) Display Garden and Trail Grounds and provides the public an opportunity to view the newest superior performers.
The following annual coleus cultivars were rated good to excellent in our recent trials:
- Heartbreaker – full sun or shade
- Main Street series – full sun or shade
- Colorblaze® series – full sun or shade
- FlameThrower® series – full sun or shade Kong® series – full shade
Coleus performs equally as well in garden beds as it does in containers. It can be planted outdoors once soil temperatures are above 60 degrees F. Plants should be spaced about 12 inches apart depending on cultivar.
These are the following requirements for choosing a site for coleus:
- Depending on the cultivar the site might need to be full shade, partial shade or full sun.
- Soil must be well-drained. To improve drainage, compost or sand can be incorporated into heavy soils.
- Coleus prefers soils with a pH of 6-7 with a high organic matter content.
Fertilization and watering
Incorporate a granular general-purpose fertilizer with equal amounts of nitrogen, phosphorus, and potassium into the soil at time of planting. After planting, coleus should be fertilized monthly using a fertilizer with equal ratios again to promote foliage growth and not flowering.
Coleus require regular watering and watering needs will differ depending on the environment the plant is placed into.
- A plant in full sun will require more frequent water than one in the shade.
- Plants grown in containers will require much more frequent watering than those grown in garden beds.
- Only water when the top 1-2 inches of soil are dry if growing in a garden bed.
- Water daily for container plants but make sure the container has drainage holes at the bottom to allow excess water to run out.
Pests and diseases are usually not an issue with coleus.
Tips for abundant foliage and healthy plants:
- Clip flower stalks as they form to promote the growth of foliage instead of flower or seed production.
- Clip off the top 2 inches of the plant right above a leaf node when it is about 6 inches tall for a bushier plant.
- Keep the soil surface clean to prevent the growth of disease.
Starting seeds indoors
Coleus seeds can be started indoors about 8 weeks prior to the anticipated outdoor planting date. Use a growing medium specifically designed for germinating seeds.
Follow these guidelines for successful seed propagation:
- Plant on the surface of the growing medium and cover with vermiculite.
- Keep moist by using a plastic cover over the seedling tray.
- Seeds require light to germinate.
- Seeds will germinate in 10-20 days at 70-75°F.
- After germination, grow plants at 65-70°F.
Starting plants from cuttings
- Coleus is easily propagated via cuttings in 2-3 weeks.
- Cut 4-6 inches off the top of the plant.
- Remove the leaves off the bottom half of the cutting.
- Place the cutting in enough water to cover where the leaves were removed.
- Once roots begin to grow, the cutting can be transplanted into soil.
Reviewed in 2021