Coleus (Coleus blumei) are known for their colorful foliage. Considered an annual in all but the warmest parts of the United States, they are sensitive to temperatures below 50 F. They make great container plants and grow well in shade, but there are some new varieties that are more sun tolerant. Coleus produce seed from flower stalks as the plants mature. They can be allowed to reseed in the garden, or the seed can be collected and sown in pots in early spring for putting in the garden after the danger of frost has passed.
Collect coleus seed from dried flower stalks of coleus plants or buy seed from a reputable dealer.
Prepare a plant container by adding a sterile potting mix. Soak the soil thoroughly with water and let drain. Do not add fertilizer.
Press coleus seeds into the surface of the soil but do not cover. The seeds need light in order to sprout properly.
Place seeded pot in a bright location, such as a window, with consistent temperatures of 70 F. Mist daily until seeds sprout, then keep damp while the sprouts continue to grow.
After two sets of true leaves appear, transplant the new coleus into a bigger pot with new potting soil and begin feeding with a half-strength water-soluble fertilizer every two weeks. If the coleus is intended to grow outside, harden off by gradually increasing exposure to outdoor conditions a little at a time (do not place in full sun) until it can stay outdoors for 6 hours without showing signs of stress.