The defense of geranium grown on the balcony
The term geranium commonly identifies Pelargonium plants, belonging to the Geraniaceae family, a name that derives from geranos which means crane, to allude to the fruit that has the shape of a crane's beak.
The Geraniaceae family also includes the genus Geranium, which differs in having leaves with a deeply incised margin, from having simpler flowers, prostrate bearing and use in rock gardens and borders.
The genus Pelargonium originates from South Africa, therefore an area with a desert climate and poor rainfall; clearly the pelargonium (geranium) must have good ability to adapt to unfavorable environmental conditions, it is in fact equipped with a root system capable of descending into the ground to a depth of one meter. In addition, to compensate for the adverse climatic conditions, it generates leaves with entire margins, very thick and covered with a light down, which reduces transpiration, while the stem is woody and knotty. Flowering occurs in all periods of the year, but in the winter period some tricks are needed to grow geraniums, which are generally implemented only at a professional level.
The first geraniums were "imported" from South Africa thanks to the passion of Italians and Dutch and later on the hybridizations began, which today gave rise to the manifold varieties of this species.
Notes on cultivation
As for the techniques for cultivating geraniums, we must remember that geranium does not withstand the winter climates of our areas, in these periods it will therefore be necessary to shelter them in special amateur or professional greenhouses, to protect them from frosts and temperature changes that would compromise their health , preventing the summer revival.
The geranium has a crop cycle that goes from 4 to 6 months. It is very demanding in terms of nutritional elements, it requires a high content of Nitrogen (used above all in the early stages to form new shoots and later for new blooms) and in Potassium (to form the color, the scent of flowers and to provide robustness to the plant), as well as iron to avoid yellowing from ferric chlorosis.
For this reason they are recommended for to grow geraniums at best, during the flowering period, of the fortnightly fertilizations, better if carried out with a liquid fertilizer diluted and administered through the irrigation water.
The ideal temperature for the cultivation of pelargonium is between 15 and 25 degrees, different conditions cause environmental stresses, which limit the flowering and development of the plant.
The geranium can be reproduced by seed, choosing the period of September for sowing, in pots containing heath land or soil, or through cutting.
The type of propagation most used in gardening is that for cutting, which must be performed by August or by September, leaving the plants outdoors, protecting them from the sun and without watering. From the end of September to the end of October the period is ideal for repotting them.
Pay close attention to the harvesting of the cuttings, which must be performed with great care, possibly using a sharp and sterilized knife.
The geraniums grown in the garden, terrace and balcony, are subject to bad weather and parasitic attacks. Much attention must be paid to the health of your geranium plant, it is in fact subject to a vast number of diseases and is prey to many types of insects which are very harmful and if neglected, even deadly.
Diseases caused by fungi
Speaking of growing geraniums, it is also good to know which diseases can affect these flowers. Among the most common diseases we have those of the collar (the area that connects the roots and the stem): these diseases can be caused by various types of fungi.
At the beginning of cultivation, the fungus Rhizoctonia solani is frequent, the most typical symptom of which is observed precisely in the area of the collar, where brownings occur which can spread to the stem or even to the root systems, creating rottenness. This type of fungus particularly affects the youngest seedlings and especially after the transplant phases.
To prevent attacks of this type it is good practice to avoid stagnation of water in the vessel, avoid putting the very dense plants in the pots to avoid creating excessively humid situations that favor the spread of the disease.
Among the other diseases caused by fungi we have then the Gray Mold, also favored by a high relative humidity.
The symptoms are represented by leaf desiccations that are covered with a showy dark gray mold.
Also in this case the most effective remedy is definitely prevention, while in the case of attacks in progress one must act with fungicides with a curative action.
The rust of the geranium has very clear symptoms, on the lower lamina of the leaf appear small bubbles of rust red color that have the particularity to release a powder of the same color.
Among the preventive measures to be implemented following this disease we have the elimination and destruction of diseased leaves. Even in the case of this disease it is good not to create water stagnation inside the vessel, for this purpose avoid watering in the evening, when it is more difficult for the water that is deposited on the leaves to evaporate quickly.
We can then still have diseases caused by bacteria (Xantomonas) whose main symptoms are leaf yellowing that occurs inside the lamina, in the form of small triangular-shaped spots with the tip pointing towards the inside of the leaf. It can also happen that the leaves fold up like an umbrella, a symptom that is found more frequently on old leaves. In the area of the stem near the collar we will also find a brown-brown area.
This disease, in advanced stages, leads to the certain death of the plant, it is therefore necessary to fight it as a preventive measure because it is difficult to cure. The fight involves the complete elimination of diseased plants and the substrate that hosts them, in order to avoid the spread of the disease to any other plants in the vicinity.
The disinfection of plants with copper-based products is a good rule.
Growing geraniums: Insects
To protect our crops, we cannot forget the many insects of which they can easily be prey.
In fact, we know that geraniums, being typically spring crops, are very subject to thrips attacks, which result in deformations of leaves and ribs, onset of bubbles and, if the attack occurs in an advanced vegetative stage, mottles and breaks of color on the petals of the flowers.
The most widespread among the thrips is undoubtedly the Frankliniella occidentalis, which presents itself, both at the larval and adult stages, of a yellow-beige color with the distinct ability to nest inside the buds, thus resulting in a great deal of retrieval difficult.
Furthermore, the serious damage caused by this insect is often mistaken for physiological alterations of the plant itself.
Fortunately, not all insects have this ability to survive or hide, in the case of Aphids, in fact, the discovery (producing an abundant quantity of sugary substance) and destruction are not difficult. For this purpose specific insecticides can be used.
Pay close attention to possible attacks by White Moscow as this annoying insect has the ability to reproduce throughout the course of the year, especially if it can find a welcoming environment like that of a plant raised in the warmth of a heated home.
It is important to administer the appropriate insecticides when the infestation is still formed by a few individuals since, otherwise, it will be necessary to alternate several active principles in order to avoid phenomena of habituation and therefore resistance to the formulations available for the fight against this kind of insect . In the case of really massive infestations it is necessary to proceed with pruning the plant at a height of about 10 cm, cutting all the remaining leaves and then burning them.
The elimination of the caterpillars is rather easy, which can also be eliminated simply by removing them from the jar with bare hands, or with the help of specific products based on Endosulfan.
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