Cold-hardy citrus is citrus with increased frost tolerance and which may be cultivated far beyond traditional citrus growing regions. Citrus species and citrus hybrids typically described as cold-hardy generally display an ability to withstand wintertime temperatures below −5 to −10 °C (23 to 14 °F). Cold-hardy citrus may be generally accepted 'true' species (e.g. Satsuma mandarin, kumquat) or hybrids (e.g. citrange) involving various other citrus species. All citrus fruits are technically edible, though some have bitter flavors often regarded as unpleasant, and this variability is also seen in cold-hardy citrus fruits. Those listed as "inedible fresh" or "semi-edible" can (like all citrus) be cooked to make marmalade.
Varieties of true citrus considered cold-hardy, ordered from most to least hardy:
|Trifoliate orange||Citrus trifoliata||−30 °C (−22 °F)||Inedible fresh||Used as rootstock and will freely hybridize with other citrus|
|Ichang papeda||Citrus cavaleriei||−18 °C (0 °F)||Inedible fresh||Parent to a number of hybrids, including the yuzu, sudachi, ichang lemon/shangjuan, and others|
|Jiouyuezao mandarin||Citrus reticulata 'Jiouyuezao'||−13 °C (9 °F)||Edible||Long cultivated in China|
|Changsha mandarin||Citrus reticulata 'Changsha'||−11 °C (12 °F)||Edible but seedy||Long cultivated in China|
|Kumquat||Citrus japonica||−10 °C (14 °F)||Edible||Fruit eaten whole with a sweet skin and sour pulp|
|Desert lime||Citrus glauca||−10 °C (14 °F)||Edible, Used in cooking.||Fruit eaten whole|
|Satsuma||Citrus reticulata 'Unshiu', syn. Citrus unshiu||−5 °C (23 °F)[full citation needed]||Edible; excellent||Long cultivated in China|
Interspecific hybrid varieties considered cold-hardy, ordered from most to least hardy:
|Citrandarin||Citrus reticulata × Citrus trifoliata e.g. Cultivar US852||−18 °C (0 °F)||Semi-edible||'Changsha' citrandarin is the hardiest citrus hybrid|
|Citrange||Citrus × sinensis × Citrus trifoliata||−18 °C (0 °F)||Semi-edible||'Rusk' is considered the most edible citrange|
|Citrangequat||Citrus japonica × Citrange||−15 °C (5 °F)||Edible||'Thomasville' is considered the most edible citrangequat|
|Citrumelo||Citrus × paradisi × Citrus trifoliata||−15 °C (5 °F)||Semi-edible||'Dunstan' is considered the most edible citrumelo|
|Kabosu||Citrus cavaleriei × Citrus x aurantium||−12 °C (10 °F)||Edible, Used in cooking||Long cultivated in Japan|
|Shuangjuan (Ichang lemon)||Citrus cavaleriei × Citrus maxima||−12 °C (10 °F)||Edible, Used in cooking||Long cultivated in China|
|Yuzu||Citrus cavaleriei × Citrus reticulata||−12 °C (10 °F)||Edible, Used in cooking||Long cultivated in Japan, where many cultivars have been developed|
|Sudachi||Citrus x junos × Citrus leiocarpa/Citrus reticulata var. 'tachibana'||−12 °C (10 °F)||Edible, Used in cooking||Long cultivated in Japan|
|Orangequat||Citrus sinensis × Citrus japonica||−9 °C (16 °F)||Edible||'Nippon' is favored for edibility and hardiness|
|Rangpur lime||Citrus medica × Citrus reticulata||−9 °C (16 °F)||Edible, Used in cooking||Long cultivated in South Asia|
|Calamondin||Citrus reticulata × Citrus japonica||−8 °C (18 °F)||Edible, Used in cooking||Long cultivated in the Philippines|
|Chinotto||Citrus x aurantium var. 'myrtifolia'||−8 °C (18 °F)||Edible. Used in cooking, too bitter to eat raw||Long cultivated in Southern Italy, Malta and Libya|
- "Isolation of genes from cold acclimated Poncirus trifoliata and Citrus unshiu" (https://etd.auburn.edu/bitstream/handle/10415/737/ZHANG_CANKUI_23.pdf])
- China/FAO Citrus Symposium "Mandarin-like Hybrids of Recent interest for Fresh Consumption. Problems and Ways of Control". FAO.
- Sauls, J. W., & Jackson, L. K. Cold-Hardy Citrus for North Florida. Document FC-36. University of Florida, IFAS Extension.
- Hardy citrus for the southeast.
- Andersen, Peter C.; Ferguson, James J. "The Satsuma Mandarin". University of Florida, Institute of Food and Agricultural Sciences Extension. Retrieved 23 May 2020.
- "Cold Hardy Citrus and Hybrids". Limette (Newsletter Citrus Friends Europe) 8: 1–2.