Geraniums are summer annuals, valued for their versatility and interesting range of bright colors, sizes and textures. Propagating geraniums by taking stem cuttings isn’t difficult, but timing is crucial. Propagating your geraniums at the correct time ensures that you’ll have healthy geraniums ready to beautify your garden with the arrival of spring.
Geraniums are propagated by taking stem cuttings from mature plants in autumn. Cuttings must be taken while the geranium plants are still green and healthy, and before the plants are nipped by frost. Taking cuttings in autumn allows the cuttings to mature indoors during the winter. The geraniums will be ready to plant outdoors when the weather warms the following spring.
Cut a healthy, growing stem tip measuring 4 to 6 inches in length. Remove the leaves from the lower one-third to one-half of the stem and pinch off any buds or blooms. Cut the remaining leaves in half widthwise, as smaller leaves require less growing space in the pot. Sanitize all tools used for cutting stems and leaves to prevent transmission of bacteria. To sanitize, wipe the tools with rubbing alcohol or a sanitizing solution of 9 parts water and 1 part household bleach.
To plant geranium cuttings, fill a pot with potting medium such as commercial, soilless potting mixture or a combination of half sand a half vermiculite or perlite. The pot needs to be at least 4 inches deep, and must have a drainage hole. Dip the cut end of the geranium stems in powdered or liquid rooting hormone. Use a pencil or a chopstick to poke a hole in the potting medium, then plant the cutting carefully in the hole. You can plant several cuttings in a container, but the leaves must not touch each other, and must not touch the soil, as leaves that touch each other or the soil may rot.
Geraniums benefit from the moisture and warmth provided by covering the pot with a clear plastic bag. Close the bag securely with a string or a rubber band. Place the pot in bright, indirect sunlight. Check the cuttings daily and mist the potting mixture if it becomes dry. Poke a few holes in the bag if water drips down the inside of the bag, as too much moisture may rot the cuttings. Alternatively, provide ventilation by opening the top of the bag for a few hours every day.
Geraniums are ready to transplant when the roots measure 1 to 2 inches. To view the progress of the roots, use an old table knife to lift a geranium cutting from the potting mixture. Replant the cuttings if the roots need more time to develop, then check the roots again in a few days. Transplant the geranium cuttings to individual containers filled with a mixture of commercial potting soil and sand. Move the new plants into bright light and continue to keep the soil lightly moist. Fertilize geraniums every other week, using a water-soluble plant food for blooming plants. Mix the fertilizer solution according to the instructions provided on the label. Move the young geranium plants outdoors after all danger of frost has passed in spring.