Mixed coleus are the perfect plants for anyone who loves lots of color. Leaves may be yellow, green, pink, red, purple, maroon, cream, bronze, variegated, and unlimited combinations of hues. No two plants will look exactly alike. These undemanding ornamental annuals average about 2-4 feet tall, and many varieties bear blooming flower spikes. Native to Africa and Indonesia, coleus prefer partially filtered light and warm locations where nighttime temperatures remain above 50 degrees F.
Although they'll tolerate full sun, colors tend to be more intense when established plants are shaded. Coleus seeds are among the easiest to grow, even for beginners. Start your coleus mix indoors in February and move them outside in May after frost has passed.
Create a seed-starting flat by cutting the lid off of an empty Styrofoam egg carton and set it aside. You'll use it as a tray for the flat. Poke several holes in the bottom of each cell of the carton with a toothpick to provide drainage.
Fill the cells about ¾ full with sandy seed starting mix. Pat the soil gently with your fingers to level it, and sprinkle several coleus mix seeds onto the surface. They'll need light to germinate, so don't cover them.
Set the tray in a container of warm water until the soil surface feels moist. Remove it from the water and allow it to drain for a few minutes and set it in the egg carton lid.
Seal the tray in a clear plastic bag to provide humidity and set it out of direct light in a warm location, about 65-75 degrees F. The top of your refrigerator or above a hot water heater is ideal. The seeds should begin germinating in about 10 days.
Check the seed flat every day to make sure that the soil surface remains evenly moist, but not soggy. Coleus seeds must not be allowed to dry out. Use a plastic spray bottle to spritz the medium with water as needed.
Poke some holes in the plastic bag to allow for air circulation when the coleus mix seeds emerge from the soil. Continue to keep the soil moist until seedlings are about 1 inch tall. Remove the plastic when they appear to be crowding each other.
Transplant coleus mix seedlings in individual 2-inch pots when they're about 2-3 inches tall. Mix equal parts of peat moss and sandy seed starting mix. Keep them evenly moist. Move them to a brighter area out of direct sun in your home, but continue to keep them warm.
Move coleus seedlings outside in may, after they've grown at least 4-6 leaves. Choose a rich, well-drained location in filtered light. Plant them at the same depth that they occupied in their growing pots, about 6-8 inches apart. Water enough to keep soil evenly moist but not wet.
Feed coleus a good all-purpose fertilizer per the packaging instructions. These plants tend to respond with growth flushes following feedings. Pinch out the top 2 newest leaves at any time that you want to encourage branching and production of bushier plants.