Often cultivated in our latitudes, citrus fruits have variable resistance to frost.
It depends first of all on the varieties, but also on the growing conditions of the citrus.
Cold hardiness depends primarily on the variety, but also on the age of the tree, its organs, the time of frost and its duration.
A brief frost at the end of the night quickly followed by a beautiful sunny day with positive temperatures should not cause any damage. Provided that the temperature has not dropped below the temperature accepted by the variety (given below in the article).
On the other hand, if the frost period lasts for several days, or even several weeks, there may be a danger for the tree because citrus fruits only have vegetative rest for a limited time.
A citrus fruit healthy and well-established will withstand frost better than a young citrus fruit or weakened by disease or pest attack.
Hence the value of carrying out a preventive treatment (against mealybugs and aphids), just before winter.
Recognize a citrus fruit that has frozen:
A citrus fruit that has frozen can be recognized by its leaves, which fall and dry up while remaining clinging to the tree.
Frozen fruits can be recognized by the fact that they are soft and necrotic or even burst. The bark of the branches is cracking.
What to do in case of frost?
If your citrus fruit has frozen, and provided that the frost has not reached all of the citrus fruit, severe pruning will be carried out to remove all dead branches and branches with broken bark.
We will also remove all the fruit so that it does not transmit disease by rotting on the tree.
This pruning will only be done at the end of winter. (When the vegetation begins to re-start)
If all of the citrus fruit is not affected by frost, then the citrus fruit may have a small chance to come back.
in general, even if the citrus seems to restart, it will remain fragile and will have difficulty in producing fruit.
Growing a citrus fruit outdoors
Growing citrus fruit in the ground is reserved for a limited area, where the winter temperatures remain positive.
The regions concerned are:
- Thelittoral Mediterranean, stretching from Perpignan to the Italian border,
referred to as the orange zone.
- The Atlantic coast, the South West such as Biarritz and, to a lesser extent, the south of the coast Breton.
- These areas can accommodate certain varieties of citrus in the ground. (kumquat, mandarin, satsumat)
However, be careful, not all of these areas are safe from frost.
On the Mediterranean coast, the winters of 1985 and 1986 damaged a large part of the citrus fruits that were in the ground. Many lemon and orange trees, however magnificent, never recovered.
Citrus fruit in a pot in winter
For citrus fruits grown in pots, it is best to bring them in locally, with or without heating.
A temperature of 4 to 6 degrees is very good for keeping a citrus fruit in winter.
The care to be provided:
During the rest period, the health of the citrus fruit should be carefully monitored. In particular, for plants under shelter, scale insects which particularly appreciate confined environments.
Citrus fruits can be treated even if they are local in winter since the temperature in the room will not be negative.
If the pot is untransportable, we can be content to protect it (the pot) with an insulator, such asbubble plastic used in the move.
The wintering veil:
For the antlers we can use a wintering veil. This saves 3 to 4 degrees and more if you double the thickness.
- The veil should be removed as often as possible to allow the citrus to breathe.
- As soon as no more frost is to be feared, the protective veil must be removed.
- Young citrus fruits are more sensitive to frost. (caution)
Read also : how to winter your plants properly
Frost resistance temperatures
Classification of citrus varieties, from the most fragile to the most frost resistant. (among the best known).
Please note that the temperatures given below do not apply to fruits which freeze well before the temperatures indicated.
The temperatures given below are for trees in the ground that are already well established, 5 to 6 years old and free from any diseases or parasites that could weaken them.
- Mexican lime lime : (citrus aurantifolia): -3 degrees.
- Tahiti lime lime : (citrus latifolia) -4 degrees. (tends to lose the sheet in strong wind and low temperature). Used ti-punch and other perfumes.
- Citron tree: -3 to -4 degrees. The citron tree is used in candied fruit and jam.
- Limequat: -3 to -4 degrees.
- Bergamot: -5 to -6 degrees. Bergamot tree is used in perfumery, bergamot tea and perfume for bombons.
- Lemon : -5 to -6 degrees. Including the 4 seasons lemon tree
- Calamondin : (apartment orange) -5 to -6 degrees. (the variegated variety of calamondin is a little less resistant -4 to -5 degrees).
- Combava : -4 to -5 degrees. Used as a side dish and spice in cooking.
- Grapefruit true tropical (citrus maxima) -6 to -7 degrees.
- Clementine : -7 to -8 degrees.
- Common mandarin : -7 to -8 degrees.
- Orange tree: -7 to -8 degrees.
- Pomelo: (citrus paradisi): -7 to -8 degrees. The pomelo star ruby variety produces fruits with pink flesh.
- Sour orange (bitter orange) -9 degrees. Used in perfumery and alcohol distillery Cointreau and Grand Marnier, orange marmalade, or as an ornamental tree.
- Mandarin satsumat tree : -10 -12 degrees. The fruit freezes from -3 to -4 degrees
- Kumquat : -10 -12 degrees. The fruit freezes from -3 -4 degrees.
- Poncirus trifoliata : -20 degrees. The only citrus with deciduous foliage.
Some parts of the tree are more sensitive to frost, such as young shoots, flower buds, fruits, an already old branch will tolerate frost better than a young shoot.
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