About 200 species of perennial, bulbous and rhizomatous plants belong to the genus Iris, widespread in nature in Europe, Africa and Asia, and the multiple hybrids created by man over the past decades. Among the various species the differences are decidedly very evident, so much so that many authors have divided the genus into different subgenres, in order to better describe the characteristics of these plants. All the specimens of this genus have particular flowers, subdivided into sections, three facing upwards, and three facing downwards, or parallel to the ground, with the tepals often endowed with labellum, and various colors, from yellow to deep purple. In Italian gardens very popular are the iris barbata, or those with a rhizomatous root, which bloom in late spring, and produce large leaves with a sword, gray-green in color, and large flowers with enormous tepals, with hanging apices. In recent years, bulbous irises are also very widespread in cultivation, having smaller flowers than those of the bearded variety, often (but not always) with tepals parallel to the ground, lacking the typical hanging lip of the bearded variety.
These irises produce small elongated bulbs, which over the years tend to shrink, producing small bunches of bulbs; most bulbous irises produce thin, cylindrical, or ribbon-shaped, elongated, light green leaves. Often the flowers bloom before the foliage, especially in the species that bloom in late winter. The flowers are supported by a rigid and erect stem, which bears a single flower; compared to I. barbata, the flowers of bulbous specimens are smaller, but the appearance is quite pleasant. There are obviously hybrids and cultivar varieties, usually dwarfs, in order to make these flowers cultivable also in pots on the terrace, or even with flowers with particular colors.
Small flower, native to Turkey, blooms at the end of winter, producing large, golden yellow, fragrant flowers on stems only 15-25 cm high; of easy cultivation, they are very rustic, and prefer sunny locations, with a soft, very well drained soil. They tolerate drought without problems, and after flowering the bulbs immediately tend to produce new bulbils; this often causes an overpopulation, which does not allow the bulbs to bloom again every year. For this reason, they usually come off and tend to plant new bulbs every year, so as to leave time for the bulbils to ripen for flowering, without leaving the flowerbed bare for a couple of years.
Bulbous plant of Asian origin, in particular it comes from Afghanistan and the surrounding areas. It produces large leaves, with a waxy appearance, slightly leathery, which develop along a thick stem; at the end of winter or early spring large yellow or white, yellow and white flowers bloom at the leaf axil. The flowering is quite prolonged and every single bulb can produce many flowers; scented varieties exist. These flowers prefer sunny locations, with well-drained soil and require little care.
Plant native to Syria, Turkey and Iran; it looks very similar to iris Bucharica, and in fact the two species are united in the same subgenus, called Juno; therefore it produces an erect stem, with large fleshy leaves, of a light green color. In spring it produces large blue, or blue, or dark blue flowers, often with yellow or white areas, on the downward-pointing petals. The flowers of these specimens are scented.
One of the most widespread bulbous rice in cultivation in Italy, belongs to the subgenus Hermodactyloides; the small bulbs tend to shrink, creating beds of thin cylindrical-section leaves, which resemble large era leaves; at the end of winter, between the leaves stand fleshy stems, 15-20 cm high, which bear large blue flowers, with yellow or orange patches on the downwards petals. There are many hybrid varieties of iris reticulata, also with blue, white, yellow, violet, dark purple flowers.
Bulbous plant native to Spain and the Pyrenees area; It is also known as the English iris, due to the fact that the one who classified them for the first time saw them in England and not in the area of origin. They have large flowers, blue-violet in color, with the petals in the lower part very enlarged, slightly reminiscent of the iris barbata. They produce thin erect stems, up to 45-65 cm tall, with long sword-like leaves, light green. Also these specimens bloom in late winter, and often the plants begin to sprout when the climate is still decidedly very rigid.
Cultivate bulbous irises
There are very many species of bulbous irises of nature, but in the nursery in fact there are very few, most of which are then hybrids; for this reason, despite the many species existing in nature, and therefore the different possible needs, we can indicate a general method of cultivation of these plants, given that those that we will find in the nursery will belong to the species that can easily be grown in our gardens. If instead we decide to start a collection of specimens of particular species, we will have to inform ourselves about the particular needs of each individual species.
Typically the bulbous I. have quite large and fleshy bulbs, which should preferably be planted in groups, so as to give rise to a patch of flowers; they settle in a sunny place, far from the shade, in a very well drained, soft and quite fertile soil; we avoid too thoughtful and clayey soils, because besides suffocating the development of the bulbs, they can favor water stagnation, which leads to the development of harmful fungi. These bulbs are planted in autumn, at about two or three times their depth diameter, and leaving the space of a bulb around each of them; watering in general is not necessary, as in autumn and spring the rains help us; it is clear that if the season should be particularly dry in spring, when we see the first shoots, we will have to water lightly, avoiding to leave the soil dry for a long time. After flowering, water the leaves at least once a week, adding, every 15 days, fertilizer for flowering plants to the water for watering. After the leaves are dried, the plant enters vegetative rest; in this period we avoid watering and leaving the bulbs at rest. We can also grow irises in pots, especially the smaller species, which do not exceed 15-20 cm in height; remember, however, that if in the garden the irises can be left undisturbed for years, in pots it would be appropriate to remove them from the ground in summer, and reposition them in the autumn, selecting only the largest bulbs and spacing them conveniently.
Pests and diseases
Usually these plants are not affected by parasites, also because their period of greatest development is the end of winter, when the climate is too rigid for aphids and mites; the problem that most often occurs is related to the development of fungal diseases, which occur only if the bulbs are cultivated in a decidedly less draining soil, or in a very humid climate. Excessive watering is harmful especially during the summer, when the bulbs are in complete vegetative rest, and can rot completely without us even noticing. Bulbous irises are also prone to ink pain, although generally new hybrid varieties are resistant to disease; it manifests itself with dark spots, also black, on the foliage, and with a consequent deterioration of the whole plant. If we notice it, we eradicate the affected plant and burn it.
Bulbous irises: Propagate bulbous irises
As mentioned before, bulbous irises tend to accel with great ease; therefore, if we plant a single bulb, after a couple of years we will find ourselves with a small patch of bulbs, all of different sizes; to be able to flower the bulbs must have the right dimensions and must be able to enjoy a little space; therefore it is very simple to propagate these bulbs simply by taking them from the ground, in summer, and repositioning them more widely; it is clear that the smaller bulbils will take a few years before they can bloom. These bulbs can also be propagated by seed, but most bulbous irises on the market are hybrids, and therefore we will probably find ourselves with plants that produce flowers different from those of the mother plant; in addition to this, a bulbous plant made from seed will take about a couple of years to produce a bulb, and an equal number to expand it sufficiently to be able to bloom.
The genus known as Iris contains something like two hundred species of plants all belonging to the family of
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