Cold Hardy Citrus

Cold hardy citrus is a general term describing citrus with increased frost tolerance which may be cultivated far beyond traditional citrus growing regions. Citrus species and 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.

Cultivation

Need paragraphs about effects of rootstocks, microclimates, winter dormancy, etc.

Varieties of cold hardy citrus

Place varieties of true citrus considered cold hardy here. Order list from most to least hardy. Of course hardiness and edibility are subjective. Keep notes short.

Name	Hardiness	Edibility	Notes
Trifoliate orange (Poncirus trifoliata)	−30 °C (−22 °F)[1]	Inedible fresh	Used as rootstock and will freely hybridize with true citrus.
Ichang papeda (Citrus ichangensis)	−15 °C (5 °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)[2]	Edible	Long cultivated in China
Kumquat (Citrus japonica)	−12 °C (10 °F)[3]	Edible	Fruit eaten whole with a sweet skin and sour pulp.
Changsha mandarin (Citrus reticulata 'Changsha')	−11 °C (12 °F)	Edible but seedy.	Long cultivated in China
Satsuma (Citrus reticulata 'Unshiu', syn. Citrus unshiu)	−10 °C (14 °F)[1]	Excellent	Long cultivated in China

Interspecific hybrids

Place interspecific hybrid varieties considered cold hardy here. (i.e. Citrange, Citrangequat, etc.) Order list from most to least hardy. Of course hardiness and edibility are subjective. Keep notes short.

Name	Hardiness	Edibility	Notes
Citrandarin (Citrus reticulata × Poncirus trifoliata)	−18 °C (−0 °F)	Semi-edible	'Changsha' citrandarin is the hardiest citrus hybrid.
Citrumelo (Citrus × paradisi × Poncirus trifoliata)	−15 °C (5 °F)	Semi-edible	'Dunstan' is considered the most edible citrumelo.
Citrange (Citrus × sinensis × Poncirus trifoliata)	−15 °C (5 °F)[4]	Semi-edible	'Rusk' is considered the most edible citrange.
Citrangequat (Citrus japonica × Citrange)	−15 °C (5 °F)[4]	Edible	'Thomasville' is considered the most edible citrangequat.
Yuzu (Citrus ichangensis × Citrus reticulata)	−12 °C (10 °F)	Used in cooking.	Long cultivated in Japan, where many cultivars have been developed.
Orangequat (Citrus sinensis × Citrus japonica)	−9 °C (16 °F)	Edible	'Nippon' is favored for edibility and hardiness.

References

1. ^ ^{a b} Isolation of genes from cold acclimated Poncirus trifoliata and Citrus unshiu (Abstract)
2. ^ China/FAO Citrus Symposium Mandarin-like Hybrids of Recent interest for Fresh Consumption. Problems and Ways of Control.
3. ^ Sauls, J. W., & Jackson, L. K. Cold-Hardy Citrus for North Florida. Document FC-36. University of Florida, IFAS Extension.
4. ^ ^{a b} Cold Hardy Citrus and Hybrids. Limette (Newsletter Citrus Friends Europe) 8: 1–2.

External links

• The Citrus Industry Volume 1 & 2