No seeds, no problem — how to asexually propagate geraniums
By Lloyd Thompson
WSU Chelan/Douglas County Master Gardener
There are really two main types of plant propagation: sexual, which is by seed, and asexual, which can be broken down by what plant parts and methods are used.
Asexual propagation plant reproduction uses roots, stems or leaves of a parent plant, and results in a genetically identical plant to the parent plant. Some common asexual propagation methods include growing plants from tubers, bulbs, rhizomes and stolons so you really just need to divide and move things to new locations. Other asexual propagation techniques include stem cuttings, leaf cuttings, grafting, layering and tissue culture. It’s a group that requires a little more knowledge and assistance.
The first thing to do is a little research on which propagation method is best for your plant and then figuring out how to make it work for your situation. Not taking the time now usually results in less-than-satisfactory results later. One of my favorite asexual propagation techniques is geranium stem cuttings. I overwinter my favorite geraniums in a pot, then take stem cuttings during the winter. Timing depends on how large you want your plants to be, and a little experimenting to find what works for your situation. I do my stem cuttings in early January before I start planting seeds. That way I can utilize my domes and heating mats when I need them for seeding.
Using a clean sharp knife, take 3- to 4-inch stem cuttings from the terminal ends of the shoots just below a node. If you cut above the node, it tends to rot up to the next node before it starts to root. Pinch off the lower leaves that will be inserted into your rooting medium.
Most instructions say to then dip the base of each cutting in a rooting hormone. However, I do not use rooting hormone when I do geranium cuttings, as I have found the success rate tends to be lower. I put my cuttings in straight perlite in a standard flat, although you can also use other mediums if you prefer. Pots and flats with drainage holes in the bottom are also suitable rooting containers.
Insert the cuttings into the medium just far enough to be self-supporting. After all the cuttings are inserted, water the rooting medium. Allow the medium to drain for a few minutes, then place a clear plastic bag or dome. I use the taller domes over the cuttings to prevent the foliage from wilting and help maintain a more uniform moisture level in the perlite.
The temperature for starting geraniums is wide, ranging from 50-80 degrees Fahrenheit. I like to root my geranium cuttings around 55-60 degrees nighttime temperature and 65-70 degrees daytime temperature. Increasing the temperature will result in faster growth, but they tend to have leggier growth.
Finally, place the cuttings in bright light, but not direct sunlight. I use two LED tube lights side by side and a heating mat under the flats. The cuttings should root in six to eight weeks. When the cuttings have good root systems, remove them from the rooting medium and plant each rooted cutting in its own pot. Place the potted plants in a sunny window or under artificial lighting until spring. One potted geranium can yield a lot of rooted cuttings to share with friends and family.
This is a good project to do with kids. They love to see the root growth and changes as the stem cutting develops. Using perlite allows for easy inspection of the roots as they form without damaging them. It is an awesome way to encourage future gardeners through an easy hands-on activity that will last all summer.