Geraniums are tender perennials grown across much of the U.S. as annuals. Although they thrive outside during the summer, geraniums do not tolerate frost and must be protected from the cold. Many prefer to bring geraniums inside to overwinter in a cool room or in the cellar. These plants remain dormant and do not produce new foliage until spring. For bright geraniums on the window sill during winter, take stem cuttings in late summer or early fall.
Make a cut 1/4 to 1/2 inch below the third leaf node on a 4-inch stem on new growth, using a sharp knife. This leaf node is the swollen area where leaves join the stem.
Remove the leaves on the bottom 2 to 4 inches of the cutting, using the knife. Leave one or two leaves at the end of the stem.
Pour a small amount of rooting hormone in a disposable cup. Dip the bottom inch of the cutting in rooting hormone. Tap the stem on the side of the cup to remove loose rooting powder.
Insert the cut end to a depth of 1 inch in rooting medium. Mix equal parts perlite and peat moss. Water thoroughly to moisten the soil mixture.
Place the cuttings in a north or east window to root.
Water when the soil dries, but avoid soggy soil. Geraniums root best when soil is kept slightly dry. Roots form in three to four weeks.
Tug on the plants gently to test for roots. If they resist your efforts, roots have formed. Pot individually in 4-inch pots.
Fertilize with a balanced fertilizer (20-20-20) mixed to 1/2 strength one week after transplanting. Repeat every two to four weeks.