Wayne Handlos, Ph.D.
Once you have a collection of Pelargonium plants you will want to share them with others or increase your
stock so you have more plants for creating flower beds or filling multiple pots.
The most common method for propagating pelargoniums/geraniums is by cuttings. This is what in the past
was called "taking slips".
While it is possible to grow geraniums from seed, seeds from open-pollinated flowers will not usually produce a plant
identical to the parent. Most highly regarded cultivars are hybrids and can only be reproduced consistently by cuttings.
So the only way to reproduce the plant you see is through vegetative means, i.e. taking cuttings and maintaining the clone.
Cuttings are taken from the ends of actively growing stems. The terminal two to four inches are cut from the parental plant
with a sharp knife, razor blade or shears. The shoot should have at least two to four large leaves. Cut the stem just below
a node (the point where the leaf is attached to the stem). Roots will only develop from the region of a node. Remove the
leaves from the lowest one or two nodes. Bend the leaf until it breaks cleanly from the stem. (In some of the scented varieties
of Pelargonium, the leaves may have to be bent carefully to the side so as not to strip tissue from and damage the stem.)
Then remove the stipules from each node. These are the little flaps of tissue on either side of the petiole (leaf stalk). When
finished, your cutting should still have two to four large leaves. If the leaves are very large, you may reduce them in size by
cutting away one-third to one-half of the leaf blade. Remove any flower stalks and small flower clusters.
The cutting are then placed in potting mix which is lightened up by adding perlite (or, less desirably, vermiculite) to a
commercial potting mix. The mix should contain about one-third to one-half perlite (or vermiculite). Some growers prefer to use
just plain perlite. If you have a problem with cuttings rotting, you might prefer perlite.
Dip the cut end of the cutting in powdered willow bark (which can be obtained in some health food stores or on-line).
(Commercial rooting hormones do not seem to be beneficial on Pelargonium cuttings.)
It is easiest to root the cuttings in their own pots; a two inch pot is about the right size. Make a hole in the potting mix (a pencil
works well) and insert the cutting so that at least one node is covered by the mix. Push the mix gently around the cutting to firm
it in place. Add a label to the pot so you remember the name of the cultivar. Use a pencil to write the label because many
Water the cutting gently and thoroughly so that water comes out the bottom of the pot. Keep the cutting out of direct, hot sun
for a day or two. Keep the medium moist but not soggy. Some modern zonal varieties may root within two weeks (they are
selected for their rooting ability), but some varieties may take much longer. Older, woody stems tend to produce roots much
more slowly and you may have to wait six weeks or more for a root system to develop.
If you are making cuttings from several different cultivars, disinfect your knife, blade or shears between plants. Dip the blade
in rubbing alcohol. A 10% solution of bleach will also work but may corrode some blades. Disinfecting the blade will reduce
the transmission of disease organisms and viruses from plant to plant. Be sure to wash old pots before reusing them.
Plants may benefit from bottom heat especially during the cooler days of the year. Propagating mats are available for this
purpose at some garden centers or on-line.
When you see roots coming out of the bottom of your pot, the cutting is ready to be planted in regular potting mix. Invert
the pot and gently tap it against a solid surface until the rooted cutting and rooting medium fall from the pot. Carefully place
the rooted cutting in a slightly larger pot, add soil, tap gently to settle the mix and water carefully. You are on your way!