To the genus hibiscus belong several tens of species, including shrubs, annual plants, perennial herbs and even small trees; most hibiscus species originate from Asia, but dinners are also from North America, Africa and Europe. In Italy, in our gardens, only a few species are present, but their beauty has led us to produce numerous hybrids. While in Italy it is purely an ornamental plant, in Africa and Asia, the hibiscus has various uses; the flowers of this plant are edible, and are used in salads, but also as a natural colorant. Also the foliage of some species is used, usually boiled or steamed.
Very well known is the use of hibiscus sabdariffa flowers in the preparation of infusions, we all know karkadи, which is easily available even in Italian shops: it is prepared with the dried flowers of this variety of African hibiscus, and comes for this purpose used all over the world, especially in Africa (karkadи in the Mediterranean area), in Asia (gudhal in India) and in south America (gongura, in Brazil). Other species of hibiscus are cultivated for other purposes, for example Hibiscus cannabinus is an annual or biennial herbaceous species that produces long thin stems, similar to bamboo canes, which in a single vegetative season can reach three meters in height; from these rods fibers are obtained that can be used to produce paper or fabrics.
Species widespread in Italy
Species widespread in ItalyHibiscus rosa-sinensis
It is also commonly called the evergreen hibiscus, because its large leaves with wavy edges, shiny and dark, are persistent on the shrub, and fall only in case of extreme drought during the winter months. In fact, in Italian nurseries, rather than specimens belonging to the species, we find some hybrid varieties, with large flowers of surprisingly intense colors; the evergreen hibiscus flowers are huge, trumpet-shaped, and are produced from a fairly messy shrub, which generally does not exceed 80 cm in height. The thin and well branched stems are dark, almost black, and stand out among the foliage. The flowers come into bloom and wither in a single day, and are generally fragrance-free; but a single plant can produce dozens of flowers, with a flowering that lasts for many weeks, from late spring to autumn.
They are fairly demanding plants, which need to be planted in a well-lit place, possibly with a few hours of direct sunlight every day. They prefer a fresh, well-drained soil rich in organic matter. They are often cultivated in pots, as they can fear very intense winter cold; however there are very cold hybrid varieties that can withstand winter temperatures below -5 ° C.
In areas with cold winters the evergreen hibiscus is kept indoors for as long as the minimum temperatures are below 10 ° C; preferably it would be advisable to avoid keeping these plants in the apartment, and place them in a slightly heated stairwell, or on a terrace, in the sun, in a protected place. At the end of autumn, to favor a more compact growth of the shrub, it is pruned quite vigorously, in order to stimulate the production of many lateral branches the following spring.
The rosa-sinensis hibiscus flowers are available in nurseries in all shades, from pure white to pink, from yellow to blood red; hybrids have particularly intense colors and often very large flowers.
Better known as a garden hibiscus, it is a species of hibiscus native to Asia, very resistant to cold, with deciduous leaves. The shrubs are large, and can quickly reach 150-170 cm in height, if not pruned; they have slightly rough leaves, medium green, not particularly decorative; starting from the spring, until the end of autumn, the hibiscus shrubs produce many trumpet-shaped flowers, white, pink or lilac; there are double-flowered or stradoppio hybrids, generally quite showy in color, compared to those of non-hybrid plants, which maintain an almost pastel color. These shrubs are widespread in cultivation in Italian and European gardens, as they survive and bloom even in unfavorable conditions, still producing abundant blooms.
They prefer well-drained soils, but they also tolerate conditions characterized by high humidity or drought that lasts over time. They do not require winter coverage, as they can withstand temperatures even close to -15 ° C.
They prefer, however, well sunny positions, otherwise they tend to become slightly floriferous; to improve the general appearance of the bush, in autumn all the branches are shortened by about half, otherwise with the passing of the years the hibiscus tends to empty itself in the lower part.
During the winter months the hibiscus loses all the foliage, which leaves the gray and smooth stems completely empty; the rather sad appearance of the shrub during the cold months is completely forgotten when the first spring flowers arrive.
Large herbaceous plant native to North America; the stems are thin, erect, and not very branched, and bear large palmate and finely incised leaves, which are very reminiscent of cannabis, of a dark and glossy color. During the summer months, large bright red flowers bloom among the leaves. The plant grows from mid-spring, producing a tuft of erect stems, until late autumn, when it completely dries up, to reappear the following year. This plant is planted in a partially shady place, where sunlight reaches it only during the coolest hours of the day; It is a delicate plant, and therefore can be grown in the garden throughout the year. In a single vegetative season a coccineus hibiscus can develop up to a meter high, producing countless large flowers; it is therefore an excellent choice as a background plant in the flowerbed of the annuals, or even as a single specimen or among the mixed-border shrubs.
Another shrub of North American origin, it is almost an aquatic plant, since in nature this plant develops along the banks of rivers, or near ponds and marshes; this hibiscus also loses its foliage in winter, and is very resistant to cold, withstanding temperatures close to -10 ° C. It produces large green leaves, slightly rough, of various shapes, from lobed to simply with a slightly wavy edge; the flowers are bees, often presenting the center in a contrasting color to that of the petals. They settle in a good soft and loose soil, of average fertility, in a sunny or partially shady place; the more we live in an area with very high summer temperatures and a dry climate, the more it is advisable to place our hibiscus in partial shade, as these hibiscus do not particularly like drought.
Hibiscuses tend to self hybridize with one another with great ease, obviously the breeders have been able to make the most of this characteristic, so much so that today there are many varieties of hibiscus related to hibiscus moscheutos, and with some other species, but it is difficult to know which are the ancestors of such hybrids, which show a strong resistance to cold.
Water the hibiscus
Most hibiscus species originate from wetlands: marshes, marshes, river banks; for this reason, watering is certainly a sore point and it is a matter of cultivating these plants. Apart from the hibiscus syriacus, which tends to bear drought very well, most of the other species cultivated in the garden tend to need abundant and regular watering, throughout the growing season. In general the advice is always the same: we water when the ground is dry; but in the case of some species of hibiscus it would also be advisable to water it regularly, even when the soil is about to dry out.
If left to dry, even for just a few hours, these shrubs tend to collapse the leaves, a clear symptom of dehydration; just as quickly they recover as soon as they are watered. Clearly this necessity often causes the development of harmful rots, because regular watering is often replaced by a perennial soaking life, which is not healthy for plant roots. Therefore, it is not necessary to keep the plants with a soil that is always soaked and soaked with water, it is enough to water them regularly, avoiding to leave the plant dry for long periods of time, from March until October. The plants that remain outdoors generally tend to be satisfied with the rains during the cooler months. As for the hibiscus rosa-sinensis, it may need watering even during the winter months, but surely we will have to disperse water supplies a lot.
From April to September, remember to dissolve a little fertilizer for flowering plants in the water of the watering, every 12-15 days.
Propagate the hibiscus by seed
The hibiscus develops very well by seed; the flowers are followed by small woody capsules, which explode when they ripen, scattering the seeds for the garden; if we wish to preserve most of the seeds of our hibiscus, we will have to cover the almost ripe fruits with a small envelope, or with a small paper bag, so that the seeds are not dispersed. Obviously, the result of sowing will depend greatly on which hibiscus we have in the garden; if it is a specimen belonging to a species, then the young seedlings will be identical to the mother plant; more probably, however, we will have a hybrid, and therefore the flowers of the new plants will hardly be just like those of the mother plant, more likely they will have a random color, and they will hardly maintain qualities such as double flowers, or an unusual color.
In the case of some varieties then, we will not even know the characteristics of the foliage: many hybrid varieties of hibiscus moscheutos have origins too uncertain to be able to give us directions.
Many varieties of hibiscus rosa-sinensis are then sterile, and therefore we will not be able to obtain useful seeds.
Hibiscus is sown in autumn, keeping the seeds in the refrigerator for at least four weeks, or sowing directly at the end of winter. The seeds should be kept in a warm, moist place and should receive good brightness, but not direct sunlight. To keep the soil moist at all times it is advisable to vaporize the surface often, rather than watering it from above, to prevent the fall of the water from moving the soil and seeds.
Propagate the hibiscus by cuttings
If we wish to propagate a hibiscus plant with particular flowers, the cutting is certainly the best method; in fact through cuttings we produce a sort of clone of the mother plant, with which it therefore shares all the characteristics, even if very particular; so if we have an evergreen hibiscus with huge yellow flowers, a cutting will allow us to obtain an identical plant, for foliage and flowering.
Cuttings can be produced of two types:
- The woody seed cuttings are prepared in spring, picking up the pici of the new branches, choosing the healthier ones, without flowers. The pici are removed, and the lower part is shaped like a wedge; they immerse themselves in the rooting hormone, and are placed on the ground by cuttings, moist and fresh.
-The woody cuttings are taken in late summer, taking the tips of the branches already lignified, also in this case the branches that have not produced flowers are preferred; take a cutting, cut into a wedge in the lower part and dive first into the rooting hormone and then into the ground.
Before being buried, the cuttings are defoliated, or rather it is good to detach the leaves in the lower part, keeping only one or two leaves in the apical part; if the leaves are very large, it is good to cut them in half, or remove the half as far from the twig.
The suitable soil is made up of peat and sand mixed together, and watered well, so that the peat is rehydrated completely. Once the cuttings are inserted into the soil, we will keep the environment moist and warm enough, without exposing the cuttings to the sun. Hibiscus cuttings have a good success rate, and therefore it is not necessary to prepare in large numbers; the rooting is however slow, and therefore we should not be surprised if it will take even a month before the cuttings sprout.
Pests and diseases
Typically, the first problem we encounter when we grow a hibiscus is related to watering: these plants (apart from the garden hibiscus) tend to love a humid climate and moist soil; especially in the height of summer, or during the winter months for home-grown specimens, we will often find ourselves with floppy foliage, which requires our attention. Proper watering, provided with regularity, prevents the soil from drying out completely, and also the plants to suffer from water stress.
In spring, the young hibiscus shoots are often affected by aphids, which conspicuously ruin them; these insects are easily eradicated if we immediately use a pyrethrum-based insecticide: by quickly killing the first generation, we prevent the possibility that they may have produced eggs for the second generation.
During the summer months it often happens that in a warm and dry climate the leaves are yellowish; if our plant is poorly watered, we can surely think that the yellowing is due to the presence of mites, also called spider mites, which must be eradicated with appropriate acaricides, then trying to keep the plant in a slightly wetter and more ventilated climate.
The plants grown in the apartment in the winter months are often affected by the cochineal, which nestles under the leaves, or under the nodes of the branches; this insect develops preferably in areas with a dry climate and poor ventilation, and therefore its presence is a clear symptom of cultivation practices not suitable for our hibiscus.
Hibiscus: It looks like hibiscus
Once the genus hibiscus also belonged to herbaceous plants, annual and perennial, which today are united in the genus Abelmoschus; these are plants originating from Asia, Africa and Australia, always part of the malvaceae family, which have a flowering very similar to that of the hibiscus, and with which they are often confused. The acabelmoschus has pale yellow trumpet flowers, easily recognizable by the fact that the eye is dark, almost black.
These particular plants are widespread in cultivation, especially in Asia, because their elongated pod, harvested still immature, is used in feeding. The most widespread common name of the aabelmoschus is in fact Okra: it is a vegetable, which physically resembles cucumber, despite having a more angular body, or even a long chili pepper. The okra is consumed cooked, and is a typical Asian vegetable.
The abelmoschus have linear or lanceolate foliage, and are all herbaceous, annual and perennial; therefore they do not form a real shrub, although in a single vegetative season they can become large, presenting many large flowers, and branched little stems of dark color.
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