Geraniums can be propagated by rooting sections of the stem, a propagation method that involves taking geranium cuttings from mature, healthy plants. It is important to take the cutting at the right time. Proper handling, rooting medium, light and temperature are all important factors when taking and rooting geranium cuttings.
Morning is the best time to take geranium cuttings. Terminal cuttings should be used to propagate geraniums. A terminal cutting is taken from the end of a growing shoot. The bottom end is the cut end and the top end is the natural top of the shoot. After selecting the geranium cuttings to take, one should clip the stems from 2 to 3 inches (about 5 to 8 cm) from the tip of the shoot.
A 3- to 4-inch (about 8- to 10-cm) deep nursery pot works well when rooting geranium cuttings. A sterile soil mix made up of equal parts sand and peat or sand and perlite provides the cutting with support and good drainage. Potting soil and garden soil should be avoided, because they contain bacteria and fungi that can cause the cuttings to rot before roots have a chance to develop.
The bottom leaves should be clipped off the cuttings and the two top leaves left intact. Rolling the cut end of geranium cuttings in hormone rooting powder or dipping them in hormone rooting liquid can help improve rooting success but is not required. When using a rooting hormone, only the bottom 0.5 inch of the terminal cutting (about 1 to 1.5 cm) should be coated.
The cuttings are inserted into the pots filled with sterile rooting medium so around 1.25 to 1.5 inches (3.1 to 3.8 cm) of the stem is below the soil line. Geranium cuttings require a spot that gets filtered light but not direct sunlight. Placing a plastic bag upside down over the top of the pot can help keep moisture in by creating a miniature greenhouse. The soil should be kept between 68° and 72° Fahrenheit (about 20° to 22° Celsius). A heating pad works well to provide the cuttings with bottom heat.
Geranium cuttings take from 12 to 18 days to form roots. A method used to check root development is to very gently tug the cuttings after two or three weeks. Cuttings that hold firm in the soil have developed roots. Cuttings that slide out easily have failed to root or require more time to develop roots.