Geranium - Pelargonium

Geranium - Pelargonium

The Geranium

The geranium plant originates in southern Africa and belongs to the Geraniacee family. It has an annual flowering. Its flowers have different colors and different intensity of scent. Geranium includes many genera and many species. The main genera of geranium cultivated are: the genus Geranium, more widespread in cold and humid areas and has leaves that turn red during the autumn season; the genus Erodium, its fruit vaguely resembles the beak of a heron; the genus Pelargonium is typical of the South African desert areas, it has a seven-molded flower with an irregular corolla. Geranium is one of the typical "balcony" flowers.


The best known species of geranium are: zonale Pelargonium, Pelargonium Graveolens, Pelargonium Radula, Pelargonium Odoratissimun, Pelargonium Radens, Pelargonium Grandiflorum, Pelargonium Peltatum and Pelargonium Rivulare. The first species of geranium, Pelargonium Zonale, is a plant that grows in bushes and has a semi-woody stem, rounded leaves and flowers with various shades of colors, from white to red and the totality of pink color variations. Pelargonium Graveolens is another species of geranium, it belongs to the category of fragrant geraniums: this plant gives off a particular rose scent. From pink geranium, or Pelargonium Radula, an essential oil is extracted which is used to improve and make rose essences even more sophisticated. Pelargonium Odoratissimun, a species also belonging to the sphere of fragrant geraniums, has the typical scent of apple and Pelargonium Radens, with an acrid lemon scent. As for the Pelargonium Grandiflorum it is the typical species of geranium with very elegant and refined flowers mottled with reddish-brown spots. Pelargonium Peltatum is also called geranium-ivy as it has a drooping habit attributable to the ivy plant. Finally, the Pelargonium Rivulare, a species of geranium with alternating leaves, palmate with 5-7 lobes.

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From the leaves of Pelargonium Graveolens an oil with a greenish color is extracted with a characteristic sweetish scent, it has astringent, healing, deodorant, circulation stimulant and disinfectant properties. Massaging with Geranium essential oil is useful for stimulating circulation and helps in the treatment of cellulite. Applying a small dose of this essence through compresses helps fight acne and boils. A few drops of this essence dissolved in water can be effective for inflammation of the oral cavity, through rinsing and gargling.


It is necessary, every year, in the spring season, to repot our geraniums, mixing the soil with a fertilizer rich in the so-called macroelements (nitrogen, potassium and phosphorus) which will be used respectively to obtain a more luxuriant plant, to strengthen the branches and for beauty. of the colors of the flowers and to protect against diseases, and of microelements (iron, copper, manganese, boron, zinc, molybdenum), these useful for a better growth of the plant. After a few days after repotting, the soil must be kept with greater humidity, after more time, start with less water and increase it gradually. Be careful never to leave the water in the special saucers for more than 4 hours. If you have geraniums in pots, it is advisable not to give too much fertilizer, this would increase the saline level of the soil, causing the roots to burn and making the plant weaker and more prone to disease and attack by parasites. As for the species of geranium Pelargonium Grandiflorum, a type of fertilization rich in potassium is recommended.

Cultivation techniques

The cultivation of geranium can take place in pots or in the open ground, a defect of the latter is not being able to quickly shelter the plants in case of seasonal changes or sudden frosts, however, if the soil allows it, it is always better cultivation in the ground, the plants acquire robustness and are less sensitive to attacks by parasites; they also reach larger dimensions than when grown in pots. Geranium prefers mild temperatures (around 20-25 ° C) but they have a resistance capacity even at higher temperatures, following some necessary precautions, and at low temperatures, if it is not brought to them in a sudden way. If brought gradually, geraniums are able to withstand even temperatures of 4-5 degrees below zero. The biggest problems with the geranium plant are related to too much humidity, especially when associated with heat or cold. It is advisable to periodically give the hoe strokes around the ground where the geraniums are grown, so that it is not possible to form that hard crust that would prevent it from absorbing the water and therefore the soil would not breathe; it is also a good idea to cut any dry and yellowed leaves. When planting, be careful not to damage the roots due to the breaking of the clod of earth, while when repotting the roots and earth must be cut, using a sharp knife, leaving only one clod with a diameter of about 12 cm. relation to the size of the plant.


The roots of geranium are very strong so it can also adapt to a universal type of soil, but the ideal soil for this plant should be rich in peat and clay, light, very porous and soft, these last three characteristics mentioned are necessary in how much the geranium roots spread a lot and therefore excessive water must come out.


The best time to water the geraniums is in the morning or late in the evening, remember to never wet the plants during sunny hours. Never wet the leaves because if the irrigation water contains chlorine, it would create problems for the geranium. Sometimes mistakes are made that could damage our good geranium: wet it too much or too little. In the first case, the roots are no longer able to breathe and the leaves turn yellow; in the second case the plant withers. It would be good to feel the soil with your fingers to feel if the plant needs to "drink", before proceeding with watering. During the hottest months (July-August) the geranium plant should be placed in an area where there is shade, while in the colder months it should be placed in a sheltered place but, possibly, with light. In winter, the amount of water needed by the plant is quite small, but be careful not to make the mistake of bringing the geranium to dehydration.


As for the pruning of geranium, in the absence of a greenhouse, it should be done at the end of the winter season: the branches are cut to less than half their length, if necessary, that is, in the case of too dense branches, it will be necessary to proceed with a thinning. In any case, always eliminate any yellowed and dried leaves. In new geranium plants, cut the vegetative tops to favor the development of the branches.


The multiplication of geraniums takes place by cuttings made during the summer. The sturdiest and not too herbaceous branches are chosen, they are placed in earth composed of soil, heather earth and a little sand, after about a month a first transplant is made in jars of 7-8 cm in diameter, the same this will be done after another month but with a larger vessel; now the seedlings will be able to bloom.

Diseases and Parasites

First of all, if you notice that the plant is sick and you have touched it to clean it, do not touch other plants before washing your hands, some types of diseases are transmissible from plant to plant. Some insects biting a sick plant transmit the disease to another through this sting; others, however, have the ability to kill the plant, these are the lice (aphids) and the white bow tie (aleuroide). Other enemies of geranium are the caterpillars, they feed on the leaves and it is necessary to identify them on the plant itself and, according to the special, they must be hunted during the day or at night using a light. One of these caterpillars is the Cacyreus Marschalli, this butterfly is found on the branches, it is probably triangular in shape, gray, this insect releases a sort of sticky mold; Metcalfa Pruinosa causes the part attacked by it to rot. The parasite most feared by the Pelargonium ivy is the red spider, it nestles under the leaves making them dry up.

Another enemy of geranium is rust: clusters with brown-orange or yellow dust clusters of spores develop on the leaves causing real holes.

Geranium is also threatened by the "white disease", it manifests itself on the leaf in the form of white powder, in extreme and more serious cases it can also cause deformation and fall of the leaves, in this case there will be no flowering of the buds. The appearance of spots on the leaves of the plant can be caused by too direct sunlight or a bad type of diet. A very difficult and almost impossible disease to defeat is "bacteriosis": it manifests itself with laceration and consequent death of the stem, drying and drying of the leaves.

What’s the Difference Between Geraniums and Pelargoniums

Ever wonder about the difference between geraniums and pelargoniums? For years there has been considerable confusion over what a hardy geranium really is. The annual 'geranium' (pelargonium) is often referred to as a geranium. However, they couldn’t be more different.

Where did the confusion come from? When pelargoniums were brought over from South Africa they were thought to be the same as the geranium. Thus, gardeners accidentally misclassified them, a mistake that wasn’t rectified until the 1700s. Unfortunately, the reclassification wasn’t widely accepted until much later.

While geraniums and pelargoniums are related, both being members of the Geraniaceae family. However, there are various distinct differences between the two in, growth, appearance, and seed dispersal technique.

Geranium or Pelargonium? Let's Stop the Confusion

For over 200 years now, gardeners have known that their garden geraniums (zonal geraniums, scented geraniums, ivy geraniums, etc.) were actually pelargoniums, that is, they don’t belong to the genus Geranium, but instead to the genus Pelargonium. It was a simple mistake. Linnaeus thought the plants were close enough relatives to put both types in the genus Geranium. But Charles L’Héritier saw things differently and separated them into two genera in 1789. The change was widely accepted even back then and still holds today.

This is Geranium sanguineum, a true geranium.

That wasn’t so much of an issue back when gardeners grew mostly pelargoniums (the annual types). If you used the word “geranium”, everyone understood you. But for the last 40 years or so, true geraniums (Geranium spp.) have become widely popular in temperate climate gardens. I mean, who doesn't grow either G. 'Rozanne' or G. 'Johnson's Blue'? To distinguish them from the tender (half-hardy) pelargoniums, few of which can survive the winter in temperate climates, we took to calling the latter “hardy geraniums”.

To Beak or Not to Beak?

Both geraniums and pelargoniums have a similar long, narrow, beaklike seed capsule.

Of course, the two plant generates, Pelargonium and Geranium are closely related. Both belong to the same plant family, the Geraniaceae, and both have the same long, narrow, beak-shaped seed capsule that springs open when ripe and casts the seeds far and wide. In fact, the botanical names both refer to this phenomenon.

Pelaragonium is derived from the Greek for stork, because the seed capsule is said to resemble a stork's bill, while Geranium means crane, because it’s supposed to look like a crane’s bill. Honestly, you’d have to be a fairly serious birder to be able to tell a stork’s beak from a crane’s beak ... especially if you removed the rest of the bird! The seed capsules, therefore, are essentially identical.

Time to Change

I think it's time to stop pussyfooting around. Why not call a Geranium a geranium and a Pelargonium to pelargonium?

Again, most gardeners already know the difference and are familiar with the term "pelargonium" even if they don't yet use it. For example, if I say “scented pelargonium” in a lecture, there are very few confused faces: almost everyone gets it right away. And this had become all the more necessary in that an increasing number of varieties in both genera are now being grown. When someone tells me about a new geranium they are growing, I like to know right away whether they referring to a geranium (hardy) or a pelargonium (tender).

For those who don’t quite get the difference, here’s a quick summary:

Pelargoniums (Pelargonium spp.)

Originally, all pelargoniums had asymmetric flowers, with two upper petals and three lower petals that are quite distinct, but that characteristic has been bred out of many modern pelargoniums. The average zonal pelargonium (Pelargonium x hortorum), for example, now has symmetrical flowers, with all five petals being identical.

Geraniums (Geranium spp.):

Cold-hardy (there are a very few exceptions)

  • Grown outdoors year round, almost never indoors
  • Herbaceous perennials (they usually die to the ground or to creeping rhizomes in the winter, then sprout again in the spring).
  • Always have symmetric flowers: 5 petals of approximately equal size and shape.
  • So there you go. You may say po-TAE-to and I may say po-TAH-to, but let’s all say geranium when we mean Geranium and pelargonium when we mean Pelargonium.

    A seed geranium is the near-twin of a zonal geranium. Probably the easiest way to tell them apart is by how they're sold. Seed geraniums usually cost less and are sold in packs or flats. The plants are also usually smaller overall than a zonal geranium, which costs more and is typically sold in individual pots. Seed geraniums are ideal for filling planting beds. Flowers open in a wide range of colors.

    Martha Washington geraniums, also known as regal geraniums, have showy flowers with velvety petals in shades including burgundy, pink, white and bicolor blends. Martha Washington geraniums are a cool-season bloomer that's usually available in early spring. It's a favorite gift plant for spring holidays like Easter and Mother's Day. Once flowers fade, it's tough to get more blooms, except in regions with cool summers.

    The genus includes more than 200 species, including balcony geraniums.
    Many varieties selected for their scent, including Bourbon geranium, Pelargonium graveolens Bourbon

    Maps of plants of the same genus

    • Pelargoniumcitronellum , citronella geranium, lemon pelargonium
    • Pelargonium crispum , Fragrant geranium
    • Pelargonium x domesticum, Pelargonium x grandiflorum , Pelargonium Flower, Pelargonium Delicious Pelargonium, Large Flowered Puppet
    • Pelargonium x Ederaefolio , Ederaceous geranium, balcony geranium
    • Pelargonium x Hortorum , Pelargonium area group, Pelargonium area group

    Pelargonium x Hortorum , Zona Geranio, Zona Pelargonio Group

    Dependable, Disease-Resistant, and Decorative

    Whether you cultivate it in a meandering border or a decorative vessel suspended from a pergola rafter, you can be sure that your Pelargonium × hortorum will be noticed.

    With full sun, well-draining soil, and a little bit of maintenance you can enjoy this dependable, disease-resistant classic as an evergreen perennial in Zones 10 and 11, and as an annual in all temperate zones.

    Are you growing geraniums in your garden? Let us know in the comments section below, and feel free to share a picture!

    And to learn more about growing flowers in your garden, check out these guides next:

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    About Nan Schiller

    Nan Schiller is a writer with deep roots in the soil of southeastern Pennsylvania. Her background includes landscape and floral design, a BS in business from Villanova University, and a Certificate of Merit in floral design from Longwood Gardens. An advocate of organic gardening with native plants, she's always got dirt under her nails and freckles on her nose. With wit and hopefully some wisdom, she shares what she’s learned and is always ready to dig into a new project!