Growing Citrus Fruits
Citrus fruits are among the most cultivated fruit plants in the world, they are large shrubs, more often small trees, of Asian origin, cultivated in Europe for centuries, but widespread in America, Australia and South Africa. These plants are part of the Rutaceae family; the most cultivated are part of the genus Citrus, (Orange, Lemon, Mandarin, Grapefruit, Cedar, Mandarancio), other cultivated genera are Fortunella (Kumquat), and Poncirus (Trifoliate orange). These plants naturally hybridize, it is therefore very difficult to understand which are the original genera and which instead hybrids originated over the centuries, in many cases there are conflicting opinions; in cultivation then there are numerous hybrids created by man, such as the Mapo, a cross between the Mandarin and the Grapefruit, of small dimensions, peel of green color and sweet and bitter pulp; clementines are instead among the most widespread hybrids, born from the crossing of Orange with Mandarin.
Many citrus fruits commonly used by us are hybrids of ancient origins, further hybridized over the centuries to obtain more juicy fruits or with a finer peel: Lemon, Citrus x limon; Orange, Citrus x Sinensis; the Grapefruit, Citrus x paradisi. Also the Mandarin appears to be a very ancient hybrid, Citrus x nobilis, although some authors consider it a type species, Citrus nobilis.
The original ascertained species are about ten, we remember the Pummelo, Citrus maxima, a very large citrus fruit, with a slightly sour taste, difficult to find on the Italian market; the Cedar, Citrus medica; the Mandarancio, Citrus reticulata; the Poncirus trifoliata.
A bit of history
Citrus fruits are grown in Italy especially in the Sicilian and Calabrian countryside, but also in Liguria (once the Ligurian crops were much more extensive than today, often abandoned to make room for cut flower crops), and in small areas on the Lake of Garda (Lemons; the cultivations of Lake Garda have left the lemon-houses on the territory: the greenhouses that were once used for this cultivation). It seems that the lemon has been cultivated in Italy since Roman times, but not in a widespread manner; it was the Portuguese who introduced the cultivation of orange in the Mediterranean, in 1500, in fact in many Italian dialects with the term Portogal, or Portugal, it means Orange. Nowadays these fruits are cultivated in most of the world countries; in Europe the largest producer is Spain, followed by Italy. These fruits have had great success over time, given the juicy and sweet pulp, and the high content of vitamins and sugars.
They are consumed mainly raw, but also candied, or in jam.
Citrus fruits are also used by the food industry to prepare juices and drinks; but also from the perfume industry, in herbal medicine and phytotherapy, where mainly the skins and fruit seeds are used.
Citrus fruits are evergreen plants of Asian origin; in the areas of origin they enjoy hot and humid summers, and fairly mild winters, with minimum temperatures generally never below zero degrees.
For this reason cultivation in Italy is widespread only in areas with a mild climate; Lemons prefer winter temperatures no lower than -3 / -4 ° C, other citrus fruits, such as Kumquats, can withstand even much more rigid temperatures, close to -10 ° C.
To promote resistance to cold it is possible to graft citrus fruits on Poncirus trifoliata plants, a Rutacea rustic with deciduous leaves: in this way Orange or Mandarin plants can also be cultivated in areas of Central Italy. In fact, the rusticity of some plants indicates only the minimum temperature at which they can survive: we want to remember that a rustic plant up to -10 ° C, survives without problems at this temperature only if reached gradually, after a period of several weeks at low temperatures ; a sudden frost, with sudden drops in temperature, can cause serious damage.
In addition, plants grown in cold climates do not always produce fruit, or sometimes give poor, or low quality, crops. Even in Sicilian areas it can happen that sudden low autumn temperatures cause the loss of a large part of the harvest.
So we grow citrus fruits in a sunny and sheltered from the wind, and, if we live in areas with harsh winters, let us put them in a container, so that we can move them to a cold greenhouse in case of very low temperatures, or remember to cover them with non-woven fabric during the winter.
Citrus fruits: Cultivation
Citrus fruits grown for fruits are evergreen plants; they bloom in spring, and some species have a second flowering in late summer or autumn, the flowers are white and intensely scented; the fruits ripen in the autumn and winter period; there are many hybrids, with different flowering and fruiting periods, so that the production can cover many months. Most of the lemon hybrids have more blooms a year, so that the production of lemons can cover practically all year; moreover, while all the fruits of the citrus fruit must necessarily ripen on the tree, otherwise once harvested the maturation stops, in the case of the lemons the maturation continues even after the harvest.
They are fairly easy to grow plants; they need soft and medium rich soil in organic matter, very well drained and not excessively clayey; generally two parts of peat are used, two parts of garden soil and a part of sand, adding some handfuls of lapillus or pumice stone. All the species, except the mandarin, do not have a rest period, therefore they need regular watering throughout the year: we water abundantly, but avoiding stagnation and always waiting for the soil to dry well between watering and the other one.
Every 3-4 months we add to the soil some mature manure, or granular slow release fertilizer; in the cultivation of citrus fruits lupine powder is used as a soil improver, which seems to guarantee excellent results, it is added to the soil in quantities of some handfuls per square meter, every 3-4 months.