In France, it is commonly accepted that citrus fruits do not grow in open ground in the area called orange blossom. In other words, on the rim of the mediterranean basin (Côte d’azur, Corsica), in regions where it freezes almost never, or very little. Also, that is to say, in almost all of the country, these trees delicate, must be grown in a pot so that the gardener can get back, come winter, in a greenhouse or conservatory, where they will be sheltered from the cold. A lemon tree of the species Citrus limon , the most consumed, is in effect completely destroyed when the temperature goes down to – 6 °C.
“Except that there are a multitude of other species very hardy delicious fruit that can be grown outside without any protection, as well at Nice, Strasbourg, Lille or Clermont-Ferrand”, “Bernard Riera, which multiplies for years a range of these “citrus fruit to the extreme” in his nursery of Venelles near Aix-en-Provence.
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Bernard Riera in the greenhouse where it multiplies its citrus plants, Venelles near Aix-en-Provence. SÉBASTIEN SORIANO/Le Figaro
there is of course the famous yuzu ( Citrus × junos) , much prized by our great cooks for its fruit, flesh pale yellow, acidic. Often called the “lemon of Japan,” while he is a native of China, like all the citrus of the eurasian continent, this small tree (3 to 4 m in height) spiny, the leaves of which exude aromas of persil, is resistant to temperatures ranging between 12 °C and 18 °C depending on the cultivars. Same thing for his “cousin”, the shangjuan (or ichang-lemon) with its large fruits, very aromatic of the size of a grapefruit and other much less well known like mandarin japanese ( Citrus unshiu or satsuma tangerine), the citrange morton, the citrangequat thomasville, delicious orange dessert USA 119, etc
“These citrus fruits and their ancestors have adapted to the cold when India, after coming into collision with the asian continent 40 million years ago, gave birth to the Himalayas. Suddenly, many of them are gradually found in areas of high altitude above 2 500 m, in what is today the Tibet and the chinese provinces of Gansu or Hubei”, emphasises Bernard Riera. This is particularly the case of Citrus cavaleriei , also called Papeda ichangensis , which, by hybridizing naturally with mandarin sunki ( Citrus reticulata var. austera ), has given birth to the yuzu, and the majority of the 4 700 species and varieties of citrus fruit identified in the Middle kingdom.
A genetic reservoir impressive
How is it, therefore, that this genetic reservoir impressive even at this point unknown in the West? “In the Nineteenth century, Europeans who were in China remained near the outlets to the sea and ventured very little inside the land in the mountain areas,” explains Bernard Riera. So, they brought back only citrus fruits adapted to the mild climate of this coastal area, namely lemon, orange and bigaradiers very sensitive to the cold that we know today, leaving aside all the rest!”
At the beginning of the 2000s, anxious to diversify the production of the nursery family, this foot-black Algerian who spent his childhood in Blida, surrounded by orange and clementine, discovered in an american publication the existence of these citrus forgotten, particularly in France. In 1896, in effect, after a terrible freeze, which destroyed millions of trees, geneticists americans hybridèrent their citrus species with rustic asian to make them more resistant. “They have left us two gifts: the orange USA 119 to the delicious taste of banana and the citrangequat thomasville, a small orange skin of the kumquat”.
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The citrumelo is resistant up to -15°C or -17°C depending on the cultivars. SÉBASTIEN SORIANO/Le Figaro
Bernard Riera is based on major collectors and nurserymen specialists, such as Sébastien Berne in Martigues (Bouches-du-Rhône), Jean-Paul Garcin in Bagnols-sur-Cèze (Gard) and Bénédicte and Michel Bachès to Eus (Pyrénées-Orientales), to bring these citrus fruits of the end of the world, very difficult to obtain. It begins with the satsuma tangerine and progressively widened its range not without having first tested the new entrants on three main criteria: the cold resistance of the tree, the early maturity of the fruit, in December, at the latest, before the arrival of cold weather and, of course, their taste. A tough job that it makes out of its activities in the nursery and the garden center that he opened meanwhile with his brother Luke in Alleyways.
In February 2012, a wave of intense cold sweeps over the whole of France. In Aix-en-Provence, the “Paris-Moscow”, the icy wind came from the East, driving the temperature down to 12 °C during a week with spikes to 16 °C. “This allowed us to test the cold resistance in real conditions and to sort important notably on yuzus from sowing: on 240, we kept only three.”
today, it offers for sale 55 citrus different, all species and varieties (grafted on Poncirus trifoliata to gain 3 to 5 °C cold resistance), that his friend Thierry Aselluccio grown over the past ten years in his small garden located next to the garden centre. “It is a bit of my show-room, I bring my clients to show them what are these trees that you do not usually see from us,” he continued. Recently retired, he now devote full time to this activity, particularly within the Association for the preservation of citrus fruit rustic and the acclimation of exotic plants that he is trying to create. Her next challenge: getting an avocado tree cold hardy native of the north of Mexico. We look forward to seeing what it looks like!