How to Grow Coleus From Seed for a Vibrant Flower Bed Filler

I love how coleus adds a pop of color to any garden or indoor space. With its uniquely colored leaves in shades of pink, lime green, and burgundy, it's no wonder it's a popular choice for many gardeners. 

As a member of the mint family, coleus is easy to grow from seed and can reach heights up to 3 feet. Whether you're looking to add some texture to your flower beds or brighten up your indoor space, growing coleus from seed is a great way to get started.

Coleus is a native in tropical areas. It thrives in warm, humid conditions and is considered a tender annual since it is frost sensitive. Because of its low light requirements, it also makes an excellent houseplant. If you grow coleus in containers, it is easy to bring indoors when the weather gets into the 50s.

You can see in this photo that I planted way too many seeds in each cell. I had to thin them down to 2 or 3 seedlings per cell.

Growing coleus from seed is easy to do. These seeds are tiny and need light and warmth to germinate.

• Sow coleus seeds indoors 8-12 weeks before the last spring frost.

• Coleus seeds are very tiny. Sprinkle them lightly to avoid having too many planted close together. You can use a damp toothpick to pick them up one at a time.

• Coleus needs light to germinate; gently press seeds into the soil or growing medium, and do not cover with more soil.

• Keep seeds moist until they start sprouting, which will take 10 to 14 days. A humidity dome helps to keep the moisture in until the seeds sprout.

• Use a heating pad if needed to keep the soil temperature at 70 to 75ºF.

• Once the seeds have sprouted, keep the soil moist by watering from the bottom.

• Use grow lights or put seedlings in a sunny window.

• Thin out your coleus seedlings once they have sprouted. They will grow faster if the roots have less competition.

• When the seedlings have at least 2 sets of true leaves, you can start hardening them off for outdoor transplanting.

• Wait until all danger of frost has passed and temperatures are consistently above 60ºF before planting outdoors.

Coleus comes in many colors and color combinations and looks beautiful in both containers and flower gardens. 

Coleus grown from seed prefers dappled sun to half shade. Too much sun will fade the bright colors and bleach the leaves. Coleus will wilt in the hot afternoon sun, so be sure to keep it well watered. As long as the soil stays moist, the leaves will spring back when the sun goes down.

Well-draining soil is important for coleus so that the roots don’t rot.

When growing coleus in the ground, water whenever the top 1 or 2 inches is dry. Coleus leaves will dry out and turn brown when it is not getting enough water.

Growing coleus in containers will mean more frequent watering than coleus grown in a ground bed. For container-grown coleus water daily, sometimes twice a day, depending on how quickly it gets hot or dries out. Make sure the pot has good drainage.

Fertilizer is not necessary when growing coleus in fertile garden soil. But a balanced fertilizer applied once a month can produce bigger plants.

Container-grown coleus will need more frequent fertilizing, as frequent watering can deplete the soil of nutrients.

Always use a balanced fertilizer for coleus. One with more phosphorus will result in a leggy plant.

These seedlings are showing their color pattern. At this point, you can make a garden plan if you want certain colors or patterns in a specific spot.

Coleus is mainly grown for its colorful foliage. But coleus grown from seed will produce flowers. Coleus flowers are typically white or a purplish blue. However, once it goes to seed, the plant will not continue to grow. For big, bushy coleus plants, pinch off the top growth to prevent it from going to seed. 

If you do want to save coleus seeds for planting, you can let it flower. After flowering, collect the seeds. Coleus will crossbreed easily, so you may get a different variation on your next planting.

Patty shares her tips for planting coleus seeds in this video.

Coleus can be propagated from cuttings. Cut off a 4 to 6-inch stem from the top of the coleus plant. Remove leaves from the bottom of the cutting. Place it in water up to the first leaves. Roots will form on the cut stem. Once the roots are growing, this new coleus plant can be planted in soil.