The Calamondin Orange Bush is a miniature orange tree producing small oranges that are very tart and acidic.
Indoor fruit trees need the right combination of good light, some indoor humidity in the winter, well-draining potting soil, additional nutrients and consistent watering. Your citrus will thrive best if it receives 8 to 12 hours of sunlight each day. The best placement for indoor fruit trees is a south- or southwest-facing window with unfiltered light. If your home receives less than that amount of sunlight, keep your indoor orange tree happy with a supplemental light system. For indoor citrus trees that receive only around 5 hours of direct sunlight each day, choose full-spectrum bulbs or fluorescent plant lights.
Four Winds Growers says citrus grows best between 55 and 85 degrees Fahrenheit. They recommend filling containers with a light, well-draining commercial soil mix. Water regularly with 1/4 to 12 gallon of water each week. In winter or in very dry climates, mist your orange tree's foliage with a spray bottle to help increase indoor humidity.