Usually self fruitful, most citrus doesn’t need pollination. Citrus is all over the globe from 35 North and 35 South of the equator.
Most citrus needs long, hot summers except lemons, which do well in fairly cool areas. The trees are mostly at low elevations to about 2000 feet. These
trees suffer when exposed to wind, so protect them if possible. Give them plenty of sun except when growing them in deserts where some shade is helpful. Dry climates are preferred to humid ones as humidity increases the risk of pest and diseases. They prefer a light, fertile loam. Assuming they’re irrigated, these can be grown in dry areas.
Most common problems are scale, whiteflies, mites, and thrips. Mature trees need several applications of fertilizer per year. The timing for this depends upon the climate.
These need little pruning. Water these as needed. Otherwise, the flowers will drop. Dry weather can affect the fruit yield, and can even cause the
leaves to drop.
Citrus needs a temperature above 50 degrees Fahrenheit in order to grow. Around 70 to 90 degrees Fahrenheit is considered ideal. Although they’re susceptible to frost, the trees will survive several degrees below freezing. Most are damaged by temperatures below 25 degrees Fahrenheit.
The following gives some idea of the hardiness for various kinds of citrus. Satsuma when dormant will tolerate 18 degrees Fahrenheit. Kumquats can tolerate it to about 16 degrees Fahrenheit. Most mandarins survive to 22-23 degrees Fahrenheit. Grapefruit and orange tolerate temperatures as low as 23-24 degrees Fahrenheit. Lemons will survive at 26-27 degrees Fahrenheit, while for limes it is 28 degrees Fahrenheit. Generally oranges and mandarin fruits freeze at 27 to 29 degrees Fahrenheit.
The duration of the cold temperature is a factor as well. Navels can take three to four hours at 27-28 degrees Fahrenheit. Lemons can take only ˝ to one hour at 29 degrees. The tangerine is the most cold tolerant.
Many kinds of citrus are suitable for containers, especially for growing indoors and greenhouses. Keep them at about 40-50 degrees Fahrenheit in the winter in a well lit place. Best growth is in the spring. Grow in large pots or tubs, and repot as needed. Keep the roots moist. Prune during the summer by removing dead growth. Thin the fruits if necessary.