Diseases geraniums

Diseases geraniums

Geranium is one of the most beautiful flowering plants in our garden or balcony. Although widespread in the external upper floors of houses, geranium can also be grown in the flower beds of the garden, giving life to a bushy plant capable of greatly enriching the aesthetic rendering of the green space. Together with the rose, the geranium contends for the primacy for the beauty of the flowers, which depending on the species can be red, white, orange or pink. Like all plants, geranium can also get sick. The main diseases of this plant are caused by fungi, insects and bacteria. The symptoms manifested by the plant can be different and not only based on the etiological agent, but also because geranium has more than 400 different species, grouped into over ten families. The most cultivated species are of the genus Pelargonia, including the zonal geranium, with red flowers, the imperial geranium, with pink or lilac flowers, and the ivy geranium, with leaves similar to the homonymous plant and pale pink flowers. The common geranium, or of the genus Pelargonia, is native to South Africa and is cultivated in temperate climates, while that of the cold areas, also known as geranium, is not very widespread in our areas. The varieties of geranium grown, as already mentioned, can undergo numerous diseases, caused by different pathogens.

Fungal diseases

Fungi can affect geraniums causing various diseases. Among the most common are rust, gray mold and rot. Rust affects geraniums of the genus Pelargonia, especially the zonal one. This disease is caused by a fungus belonging to the Puccinidiae family, the Puccinia. Despite the name, which evokes a famous musician, the fungus, also belonging to the class of basidiomycetes, is very dangerous for geraniums, as it is capable of causing a disease that can easily spread to other nearby plants. The main symptoms of rust are yellowish spots on the top and bottom edges of the leaves. As the disease progresses, it forms concentric reddish spots that can spread to neighboring plants. Infected leaves, on the other hand, dry up, also compromising the flowering of the geranium. Gray mold, caused by the Botrytis cinerea fungus, causes dark spots on the leaves and flowers. The conditions that favor the development of this disease are excessive nitrogen fertilization and abundant watering. Rot is a disease caused by the fungus belonging to the Pythium genus and is manifested by the dark, almost black coloration of the branches of the plant. They favor the development of rot, excessive irrigation, which by stagnating the water causes the root system to deteriorate, preventing the plant from absorbing the nutrients of the soil. Fungal diseases attack geranium mainly in spring, when the plant blooms and the climatic conditions present a high level of humidity. At the beginning, infections can be fought by reducing watering and nitrogen fertilization and replacing the potting soil with a drier one. In case of advanced infection, specific antifungal products must be used. The chemical fungicidal compounds are triazoles, carboxylics and dithiocarbamates. Their application is recommended in spring and summer, when the disease is at the peak of its manifestation.

Bacterial diseases

Geranium is not affected by many bacterial diseases, but there is one that, if overt, can lead the plant to death. This is geranium bacteriosis, a pathology that attacks plants of the genus Pelargonia. This disease is caused by Xanthomonas campestris pelargoni, a bacterium with a high infectious potential, capable of rapidly spreading to neighboring plants. When geranium is affected by bacteriosis, there is no remedy, but only the solution of completely eliminating the plant, uprooting and burning it as far as possible from the others. Even the “infected” soil must be replaced, while the pot must be adequately disinfected (better to eliminate it). The symptoms of bacteriosis are yellowing and browning of the leaves and a typical umbrella folding that precedes the drying and fall of the same. If geraniums are grown in the ground, it is best to disinfect it with copper-based products before proceeding to the cultivation of new plants. Conditions that favor geranium bacteriosis can be pruning errors or improperly cleaned and disinfected cutting tools.

Geraniums Diseases: Insect Diseases

Geraniums can also be damaged by many phytophagous insects, including aphids, cochineal and spider mites. The aphids feed on the sap of the geranium by pricking the foliar apparatus and covering it with an abundant sugary substance. The cochineal, especially the floury one, causes spots on the lower part of the leaves. The red spider mite causes yellowing and curling of the leaves, covering the lower edge with a thin spider web. Geranium insects are fought using natural or manual methods, if the infestation is at the beginning, or with the use of fungicides and pesticides in the event of a very extensive or difficult to contain attack.

Plant diseases and pests: how to recognize them. Symptoms and remedies

The diseases that can affect the plants in our vegetable garden, garden or balcony are very numerous. Many times the plant diseases they are caused by insects and parasites, while at other times they are linked to poor plant care or climatic conditions.

Among the most feared diseases and enemies of plants we find aphids, bedbugs, rot, heat stroke, cochineal, the presence of caterpillars, whiteflies, downy mildew and powdery mildew. To intervene in our vegetable garden, in the garden and to protect potted plants we can use non-toxic remedies and natural pesticides.

Let's find out what they are symptoms and natural remedies for the most common plant diseases.

The plant we commonly call "Geranium"Actually belongs to the genus" Pelargonium ", while the real"Geranium"Is in fact a herb that has had little diffusion as a cultivated plant.

This exchange of names originates from an ancient misunderstanding that sees two botanists of the past as protagonists: Linnaeus and Heritier, who cataloged the two plants and later corrected their classification. What today we call geranium is a flowering plant which, thanks to its scenic beauty and its resistance, has known a great diffusion as a cultivated plant.

Almost all varieties are native to South Africa, but if in hot climates the geraniums grow quickly and in a rather disordered way, here (in the cooler regions), they develop slowly which makes them perfect for embellishing flower beds, borders, balconies and windowsills. To this day they are among the best known and cultivated plants as they do not require special care, which is why they are easy to grow and give away beautiful blooms throughout the summer. They are also plants that are suitable for cultivation in jar and in flat.

Thanks to the wide panorama of variety you can find flowers of many different colors: pink, red, lilac, white, with all possible intermediate shades, in solid colors or with streaks. The bearing of the plant also varies, which can be straight, climbing or drooping stems.

In addition to being an easy to grow and aesthetically very beautiful plant, it has the advantage of ward off insects, especially the annoying mosquitoes, which are used to disturb the beautiful summer evenings.

Finally, some varieties of geranium are grown for the production of essential oils or for pharmaceutical uses.

The varieties

Botanically speaking, it is necessary to distinguish the genus Geranium (flowers with 10 stamens, spontaneous plants widespread in nature) from the genus Pelargomiun (flowers with 7 stamens, cultivated geraniums, which includes over 200 species of plants from whose crossing the about twenty best known species are derived. for ornamental use). To simplify further, on the basis of the posture, the shape of the leaves and the inflorescences, six groups are distinguished.

Zonal geranium

The zonal geraniums have a fleshy stem and a greenish-black spot on the leaves that divides the leaf blade into three zones (hence the name of zonal). Flowering is almost continuous all year round in regions with a mild climate, while in the colder ones the plants must be sheltered. They can have simple, double, semi-double, rose bud, cactus flower, starry flowers.

Imperial geranium

The imperial geraniums are less rustic than the zonal ones, therefore the cultivation must be carried out in pots. The flowers are simple, large and characterized by dark spots at the base of the petals, flowering occurs from May to August (they are not re-flowering).

Ivy geranium

The ivy geraniums and the Parisian geraniums have prostrate, branched stems and are suitable for covering walls in full sun, forming espaliers or being placed in vases for furnishing balconies and terraces. The flowers can be simple, double and semi-double they have a great growth in terms of flowers and leaves in the winter must be sheltered. The combination of these geraniums with surfinia and verbene is very impressive.

Fragrant geranium

The odorous geraniums do not have important blooms like the other species, however the leaves are particular and of a unique beauty, variegated in colors, fragrant and velvety to the touch. The white, lilac or burgundy flowers, depending on the species, are small and inconspicuous, but so delicate and simple that they are really pleasing to the eye. To be displayed on windowsills or terraces to enjoy the pleasant scent they emanate, fragrant geraniums grow vigorously, therefore they need large pots and frequent watering.


Unique geraniums have five-petaled flowers, very large and with strong colors, usually the two upper petals are a little larger, which is why they are similar to butterflies. They usually have only one flowering in late spring.


Angel geraniums bloom from March to August in a multitude of colors. They have fragrant funnel-shaped flowers grouped in umbels. They have a bushy habit, rounded and fragrant leaves require a lot of water.



He is originally from South Africa which means he feels at home in warm places exposed to the sun or in partial shade. Likes mild temperatures (around 20-25 ° C), however it also resists higher or lower temperatures, if these do not arrive suddenly. If the temperature drops far below freezing the geraniums in pots should be placed at recovery.


It depends on the climatic zone: in general it prefers asunny exposure, but in the South, placing under the scorching sun. During the formation of the flower buds it is useful not to keep the plant in full sun because in this way the flowers are colored better.


Loose is well drained on the market are found soils "for geraniums" based almost exclusively on peat. Soil should be preferred in which there is an abundance of a component that facilitates drainage, such as expanded clay or pumice.


As soon as the nights are free from frost and temperatures reach double digits during the day, the geraniums can be planted outside, usually during the May. They are buried in a balcony vase or in one planter: These pots should never be too small, as these plants appreciate plenty of space and soil. It is important to leave about 20 cm between one plant and another when placing them.

One drainage layer on the bottom serves to prevent obstruction of the drain holes. For the sowing of geranium it is preferable to use a preferred soil, made specifically for the nutritional needs of this plant, which therefore does not require further fertilization, at least for a few weeks.


Not abundant, but daily in summer one time every 2-3 days in mid-season, once a month when it is cold. Use water slightly calcareous and avoid stagnations, which are very dangerous for the plant. Leaves and flowers should not be wet so as not to cause fungal diseases.


Geraniums, being very active plants, need to be fertilize often. From April to September fertilize every two weeks with liquid fertilizers which have a higher potassium content to promote flowering: they are administered with irrigation water.

During the other periods it is sufficient once a month, by administering a fertilizer with equal quantities of nitrogen, phosphorus and potassium besides of course i microelements.

If we put in good soil and repot every year, we will give our plants a good basic supply of nutrients.


You drop more branches old is lignified, in correspondence of a node to favor the sprouting and growth of new shoots. In the South it is done in winter, in other regions it is better to do it at the end of winter. They breed mainly for cutting taking a branch of the previous season, 5-10 cm long from which any buds and basal leaves are eliminated, leaving 2-3 apical leaves, to avoid dehydration of the cutting. A mixture of soil for geraniums and river sand with which you fill a jar. Insert the cutting into the soil that must be moistened and the pot must be placed in a bright and warm area (at least 15-18 ° C).


Remove regularly dead leaves and flowers, as well as dry branches, it makes geranium more beautiful, keeps it healthy, preventing it from becoming a vehicle for parasitic diseases and stimulates the formation of new flowers. As i flowers wither, it is advisable to cut them at the height of the first couple of leaves, so that the plant does not waste precious energy for the formation of seeds. There are "self-cleaning" varieties, particularly among hanging geraniums, whose dried flowers fall off the stems before producing new ones.

In young geranium plants it is good to trim the vegetative apexes to stimulate the branching and development of the lateral branches. Perennial geraniums they bloom again if cut at a height of 15 cm and if you move to spend the winter in a bright place away from frost. During this resting period, the ideal temperature is 5 to 10 ° C and the plant requires very little water.


The most common fungal diseases are the rust, the gray mold and the rot. Rust especially affects zonal geraniums and can spread to neighboring plants. Yellowish spots form on the edges of the leaves which then dry up, also compromising the flowering of the geranium.

Gray mold causes dark spots on the leaves and flowers. The rot is manifested by the dark, almost black coloration of the branches of the plant.

Fungal diseases attack geranium mainly in spring, when the plant is in bloom. Infections are counteracted by reducing watering and nitrogen fertilization, but if the infection is advanced, we intervene with antifungal products.

Geraniums can be attacked by phytophagous insects: the aphids they prick the foliar apparatus and cover it with a sugary substance cochineal causes spots on the underside of the leaves the red spider causes yellowing and curling of the leaves. These insects are contrasted with the use of fungicides and pesticides.

There are also bacterial diseases such as bacteriosis: the leaves turn yellow and fold like an umbrella and then fall and dry out. There is no remedy, the plant must be uprooted and burned. The soil and the pot must also be replaced or disinfected with copper-based products.

Hanging geraniums

The geranium plant is well suited to hanging crops, ideal for creating fascinating multicolored compositions. This ornamental technique is perfect for designing a colorful and imaginative garden corner. In the image, rope baskets with geraniums of different colors create a beautiful variegated composition.

The hanging vases are also easily made with do-it-yourself methods, using containers of different materials such as bowls and vases in plastic or wood, tied and suspended in mid-air with ropes or strings suitable for the purpose.

Hanging geraniums are ideal for decorating outdoor or transit areas such as porches and verandas. The hanging vase method is also a perfect ploy to make the most of the spaces.

The cultivation with the hanging technique is also suitable for indoor environments a small corner of suspended flowers makes your home a pleasant and original place. Furthermore, the raised position is comfortable and practical for plant care.

In the image, a wooden structure, which supports pastel-colored and cube-shaped vases, gives the environment dynamism and a hint of joy, the very thin suspension threads are almost invisible.

Geraniums with particular settings

Gardens and balconies are not the only spaces suitable for growing geraniums. In fact, if we let ourselves be carried away by the imagination, any place can be transformed into the setting suitable for a floral composition. Even the basket of a bicycle, driven through the streets of the city, can give a shade of color to the grayness of the streets.

Geranium plants are perfect for decorating the home and for restoring some color to the kitchen as well.

In the garden, even an old wooden chair can become an original support for a pot of geraniums.

A beautiful bicycle transformed into a planter, ideal as a fixed or mobile decoration of gardens and avenues.

An old cart used as a transportable planter.

Even an old suitcase with a worn look can become a very original vase with a unique look.

Geranium plants are ideal for adding a touch of color to the corners of the house with old objects and black and white photos.

Geranium on the table

THE cut geraniums they have good stamina when stored in water. To keep the flower alive and luxuriant, it is advisable to cut an apical portion with disinfected shears and immediately place it in a well-kept container. clean and with fresh water. It is necessary to remove the leaves that are found below the water level also it is good to add a antibacterial, such as a teaspoon of vinegar for every half liter of water. Finally, it is always advisable to remove dry or diseased flowers and leaves and avoid placing plants near heat sources, such as lamps, stoves or direct sunlight.

Cut flowers are an excellent idea to decorate the table and enjoy, even in the city, a lunch or dinner surrounded by greenery.

Centerpiece with wooden tray, perfect for giving the dining room a cheerful and colorful nuance.

The geranium flower gives the "mise en place" of the dining table a unique elegance, evading the typical greyness of custom and ordinariness.

The cut flowers can be placed on a support structure to keep them in an upright position, thus avoiding the drooping effect.

With cut flowers it is possible to create multicolored scenographic compositions, using glass jars, including recycled ones, to be placed on trays that can be moved to our liking.

A flowery summer decoration, in view of a good breakfast, is the perfect way to start the day.

Geranium: cultivation

A review on geranium is always useful especially because, being a plant of easy cultivation, could be underestimated.

Let's briefly see all the steps.

L'exposure is recommended in full sun, preferably on a balcony facing south or south-east. The temperatures those are ideal medium high and, as a result, the geranium suffers the cold season. During the winter months we recommend that you repair your geraniums using for example del non-woven fabric or placing them in small greenhouses.

L'irrigation it must be precise and never abundant, because geraniums suffer from water abundance:

  • prevents i saucers fill with water
  • before watering again wait for the ground yes it is dried completely
  • irrigation is recommended in early morning,
  • water only in warmer months, while for the remaining months the water supply guaranteed by atmospheric precipitation will be sufficient

Do you want to make a drip irrigation system to irrigate your potted plants? Read here.

As for the ground, this must be acid (to measure the pH of the soil, here is an ad hoc article), fluffy, well draining and you will need to make sure that clay and of sphagnum peat.

There fertilization instead it must take place from the beginning of spring, and then be carried out during the entire vegetative period. You can choose between three types of fertilizers:

  • the organic fertilizers
  • the liquid fertilizers to be dissolved in water
  • the formulated fertilizers specifically for geraniums

Lastly, don't forget the pruning spring: remove excess plant parts and buds when they are too dense, remove withered flowers and dry leaves. If you are not an expert pruner, start with the basics.

If you want to know more about the cultivation of geraniums, we have prepared this comprehensive guide for you.

The most popular and popular varieties of geranium

In general, the 'classic' or 'zonal' geranium it is the most common on balconies and gardens as it lends itself to being cultivated with ease. The posture is erect, i round and fleshy stems, the large and round leaves characterized by a darker internal area (hence the name 'zonal').

The leaves are dark, fleshy and very resistant to heat, while the flowers range over one range of shades almost endless that goes from white to fiery red, passing through pink, lilac, purple and so on.

Fertilizers based on nitrogen

The plant no longer has the same need for nutrients it had during the spring-summer to develop and bloom, so it is necessary decrease fertilization. To treat geraniums, a nitrogen and potassium-based fertilizer supply (every 2-3 weeks until October) can be necessary to strengthen the fabrics in anticipation of winter, so as to endure and best withstand winter weather conditions and start off again the following spring.

Video: Caring for Geraniums

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