You Say Geranium, I Say Pelargonium

November 21, 2022

by Linda Summers, Washington County Master Gardener

As the weather turns colder, many people grow tired of their potted or in-ground plants, either discarding them or letting nature take its course with a frost. However, there is one plant that is very easy to propagate through stem cuttings or even by keeping the plant alive through the winter and replanting it in the spring. This plant hails from South Africa — the pelargonium — which we often refer to as geranium.

In fact, pelargoniums belong to the family of Geraniaceae, which is divided into three basic groups or genera. First are the cranesbills, so named because of their long seed pod which resembles a crane’s bill, and these plants retained the name Geranium. Second, are the erodiums, commonly referred to as rock plants because they are a low-growing, flowering ground cover frequently used in rock gardens. Third, are the pelargoniums.

Pelargoniums are distinguished from geraniums, even though they belong to the same family, because of their flower. Geranium flowers have five petals, which are all roughly the same size. Pelargoniums have two upper petals which are different in size from their lower three petals. There are approximately 280 different species of pelargoniums in the world. These plants, often grown in container pots, will not survive our midwest winter. However, unless you have a greenhouse, there are other ways to overwinter your plants.

Pelargoniums like a high light environment most of the year, so a southern exposure is beneficial to them. However, they also like cool temperatures for their best growth, so night temperatures in the 50’s suit them fine. Average temperatures are tolerated.

If your plants are leggy and have been outside during the summer, remove them from their pot, cut them back to one third to one half of their size, remove some of the long roots, and repot them with fresh potting mix. You can also take cuttings from your plants if they are large, cutting the stem on a diagonal and below a node. Use a 3-to-4-inch tip cutting with a healthy growing shoot. Remove any buds or flowers and the lowest leaf. Dip the cutting into a rooting compound and plant your cutting in fresh potting mix. If you are using a larger pot, try planting several cuttings in the same pot. Water your plants but avoid over-saturating the soil. Let the soil dry out between waterings. Rooting usually takes place within a few weeks, after which the plant can handle more water. When your plants show signs of new growth, this is an indication that the roots are growing as well. Do not fertilize your plants during the winter as this is a dormant period for many plants and not a time for a growth spurt.

An alternative to taking cuttings is to over-winter your pelargoniums in bare-root form. With this method, you dig up your plants before the first frost, shake off all the soil and allow them to dry out for a couple of days. Cut back the stems to around 4 inches and remove part of the root mass and all leaves. Place the plants in a paper bag or a cardboard box, and cover with sawdust. Store in a cool, dry place such as a garage or basement. In the spring, the roots will have to be soaked in water for a few hours before potting the plants.

For more information on over-wintering pelargoniums or geraniums, please contact your local Master Gardener or the University of Illinois Extension Office in your county.

Pictured above is a Geranium.

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