The calamondin orange tree (citrus mitis) grows 8 to 10 feet in height. A popular houseplant or patio specimen, the tree is not highly valued for its fruit. The fruit is considered to be an "acid orange." When the fruit is ripe, its flavor is similar to that of a sore lemon. The tiny fruit measures 1 inch or less in diameter. The tree was introduced into the United States in 1900 from China.
The calamondin orange tree is exceptionally cold-hardy. The tree is capable of withstanding temperatures that dip to 20 degrees F. once established.
Plant the calamondin orange tree outside when all danger of frost has passed. The middle of March tends to be the ideal planting time. Choose a location that offers full sunlight. They will survive in partial shade, but fruit production will be severely affected by lack of sunlight. The trees are tolerant of all types of soil but do require a well-drained site. The graft union of the tree onto the root stock needs to sit approximately 2 inches above the soil line.
Calamondin trees are widely sold as houseplants across the United States but are often difficult to successfully grow indoors. The trees require abundant sunlight. It is advisable to place indoor calamondin trees outside during the summer months when the temperature ranges from 70 degrees F. to 90 degrees F.
Water calamondin trees thoroughly once a week. Additional rainfall during the week is ideal. Fertilize the tree once a month using a water-soluble citrus fertilizer such as a 20-20-20 mixture. Follow the directions on the label for application instructions.
The citrus leaf miner often enjoys feeding on the new growth of the orange tree. Spray the new foliage growth of the tree with Neem oil to control the insect.
Flowers appear in the summer months alongside the previous year's fruit. The fruit of the calamondin often takes over a year to fully ripen before harvesting. Begin harvesting when the fruit begins to show the first blush of dark orange. Clip the fruit from the tree using pruning shears. The juice of the fruit is often used in marmalade and to flavor teas.
The calamondin tree requires no pruning. The tree can be lightly clipped in the spring to maintain a bushy habit or to offer a more visually appealing specimen, but it generally is unnecessary.