Dwarf citrus trees are a popular plant for growing inside not only because of the year-round fruit, but for the beautiful green foliage, which adds an aesthetically pleasing look to any home decor. The most common indoor-grown orange tree is the calamondin (Citrofortunella microcarpa), a native to China producing fruit that is a cross between a kumquat and a tangerine. It grows from 3 to 4 feet tall and bears star-shaped white flowers in the summer against a backdrop of glossy, green leaves with a light citrus scent.
It may take several years after planting for the orange tree to be mature enough to bear fruit, according to North Dakota State University. Once mature, the tree will grow 1- to 2-inch, tart-tasting oranges that turn from green to bright orange when ripe. Growing an orange tree inside is relatively easy with a few basic steps--the rewards of fresh fruit are well worth the time and effort.
Plant your orange tree in a 6-inch diameter ceramic or terracotta pot that has drainage holes. Dwarf orange trees like to be grown in small pots and the small pot helps to keep the tree compact. After three to four years, repot in an 8-inch pot. Use a well-draining potting soil to help avoid root rot caused by soaking wet soil.
Water the orange tree frequently, three to four days per week, or as needed. when the top 2- to 3-inches of soil is dry, water until it drains out of the bottom. If the pot sits on a saucer, be sure to empty the saucer of any water it collects. Yellow leaves are a sign of excessive watering and too little watering cause the leaves begin to wilt and drop.
Place your orange tree in bright, indirect sunlight, such as in front of a south-facing window. The tree should receive at least four hours of sunlight. Turn the tree a quarter of a turn every week to ensure every side gets adequate lighting and to keep the tree from leaning towards the light.
Grow the orange tree in a warm temperature ranging from 55- to 68-degrees F. If the temperature drops too low, growth will slow down. Provide adequate humidity for your tree by setting the pot on a pebble-lined tray that is filled halfway with water and misting the tree two to three times weekly.
Feed once a month with a balanced liquid fertilizer. Dilute in half and water in well when applying. The indoor orange tree can be fertilized year round as long as it is producing fruit.
Pollinate your indoor orange tree to ensure it produces fruit since it is not outside where the bees can naturally carry the pollen from one flower to another. Use a small paint brush and wiggle the brush around in the center of each flower collecting the pollen. Move the brush from flower to flower transferring the pollen to each flower.
Prune your orange tree each spring to keep it from getting too leggy and not producing enough fruit. Cut back any long, thin branches to the trunk of the tree, which will encourage new branches to grow from just below the cut made. Trim back branches to shape the tree and always cut at a 45-degree angle just above a leaf node or where the leaf attaches to the stem.
Check periodically for pests such as mealy bugs and spider mites which are the two most common pests found on orange trees, according to North Dakota State University Extension. These pests leave a white, cottony substance on the underside of the leaves and may chew small holes in the leaves. Spraying the leaves periodically with water helps to prevent the pests and if you find pests on your tree wipe the leaves with a damp cloth to remove.