Pelargonium (2017)

By Bob Williams (March 2017)

At the February meeting, Mike Hellmann brought an exquisite pelargonium as a brag plant. It was in full foliage and was sending out a large number of flower stalks. The woody trunk gave it a bonsai feel. After talking to members, it seems many grow different species of Pelargonium. After reading about these plants, it seems many species will be in bloom now or in the near future. This should provide a colorful and fragrant display for our next meeting.

Pelargonium is a genus within the Genaniacea family, which also includes geraniums. In fact, many garden centers sell pelargoniums as geraniums. These plants look similar to each other. The flowers of pelargoniums are what truly differentiate them from true geraniums. They have five petals – two upper petals that differ in color and pattern from three lower petals. Geranium species have symmetrical flowers with petals all the same size and shape.

Pelargonium flowers have two to seven fertile stamens, while geranium flowers have 10 or more. In addition, pelargonium seeds have a plumed end to help them float away on the breeze, while geranium seeds lack the plume and are “flung” from the plants.

The name Pelargonium refers to the shape of the fruit and is derived from the Greek for “stork’s bill.” Another way to tell the difference between a geranium and a pelargonium is that no pelargonium is winter-hardy, while some geraniums are. Sorry, Jolie.

As with last month’s succulent of the month, I think that everyone in the club has grown a pelargonium. Pelargonium citrosum tends to be a popular plant at garden centers, where it often goes by the more common names of citronella plant or mosquito plant.

The majority of true Pelargonium species are native to South Africa. There are also about 20 species in eastern Africa and a few others in Australia, New Zealand, Tasmania, Turkey, Iraq, and islands such as St. Helena and Madagascar. Depending on the source, there are between 250 and 300 species in the wild, plus many more cultivars.

Most of the plants found in South Africa are found in the southwestern part of the country. They grow as a low, shrublike plant in the wild. They reach a height of 4 feet with a similar diameter. A few are found in crevices on rocky cliffs.

The leaves and flowers are highly scented. Some of the more-scented varieties are important in the perfume industry, which extracts oil from their leaves. The scents include compounds of the essential oil produced by the leaves include citronellal, geraniol, eugenol and pinene.

Some pelargoniums are also thought to have antiseptic and antibacterial properties. Rose geranium, Pelargonium graveolens, is particularly used for skin care products such as lotions, soaps and washes. Many African tribes used some Pelargonium species to treat respiratory problems. From the 1880s through the early 1900s, English doctors used some pelargoniums to treat tuberculosis with success.

In my research, there seem to be 60 to 80 species that are considered “tuberous” and grown as a caudiform or succulent woody plant. These would be of interest to our group.

They are winter growers in our climate. They are dormant during the summer and should be shaded and protected from our summer rains. When the temperatures start falling in the fall, the leaves will begin to sprout. That is when you should begin watering. Water when the plant is almost dry and do not keep the potting mix moist all the time. This mimics the growing season in South Africa, where the raining season occurs in the winter months.

When growth starts, pelargoniums should be placed in windows or a section of the house that gets bright light. They cannot survive the cold and should not be in a room where the temperature may reach the 30’s. As with most of our plants, the potting mix should drain well. Begin fertilizing when growth starts.

I found a website where one person found the best fertilizer for his pelargoniums was tomato plant fertilizer used at one-quarter strength twice a month. Flowering will be in the February through April timeframe for us.

Propagation can be by seed, leaf cuttings or separating the tubers. In my research, there seems to be a couple of things to do when starting from seed. The first is scarring the seeds. There are different ways to do this.

It may be soaking the seeds in water to soften their casings. Some people use a slightly acidic liquid in which to soak the seeds for a short period of time. Others use a nail file to scratch the seeds. This is to replicate nature, where birds eat the fruit and partially digest and soften the outside part of the seeds.

I can’t list all the species that seem like interesting plants. The following websites, just three of many, describe some of the more interesting species and provide in-depth information:

Garden Design Magazine – https://www.gardendesign.com/plants/pelargoniums.html
Succulent Plant Page – http://www.succulent-plant.com/families/geraniaceae.html
Pacific Bulb Society – http://pacificbulbsociety.org/pbswiki/index.php/Pelargonium

There are many sources from which to buy pelargoniums. There are the normal sources that many of us use. Geraniaceae.com, a vendor in California, has a huge variety of plants for sale and a large amount of information. Some of the plants for sale are from wild-collected seed the owner obtained from her trips to South Africa.