Coleus are popular plants for good reason. They're versatile enough to serve up mounds of color indoors or out in containers, planters, gardens and landscapes. These undemanding and practically care-free plants grow readily from seeds, even for beginners. Although the seeds of your beloved coleus are tiny, there's really very little involved in collecting and saving them to propagate your favorites the following spring.
Check your coleus plants daily once the flowers on the bloom spikes begin to die in the fall. Allow the stems to turn completely brown.
Use sharp, clean shears to cut the bloom stalk from the coleus plant. Don't try to just pinch or pull it off because you'll probably pull the plant up by its roots. Wrap the stalk loosely in a paper towel for safe transport to the indoors for processing.
Remove the coleus bloom stalk from the paper towel and drop it into a small paper bag. Place the bag in a warm spot out of direct sunlight and allow the stalk to air dry for 2 weeks. A room with low humidity and good air circulation is best.
Shake the bag each day to keep the seed pods from sticking to each other and encourage the evaporation of moisture. Some of the seeds will begin to fall from the spikes into the bag as they mature during this time.
Pull the bloom spike between your thumb and forefinger to strip the pods from it, allowing them to fall into the bag.
Fold a piece of plain white paper in half and crease it well. Open it up and dump the contents of the bag onto it. Squash all of the seed pods with your fingers to break them open. The ripe coleus seeds will pop easily out of the pods.
Fold the paper at the crease, enclosing all of the seeds and debris. Remove the lid from a pepper shaker and pour the material into it. Cap the container and shake the tiny seeds back onto the piece of paper, leaving the unwanted material in the pepper shaker for easy disposal.
Store the coleus seeds in a paper envelope in a cool, dry location out of direct light until you're ready to plant them in the spring.