Yard and Garden News
By B. Rosie Lerner, Extension Consumer Horticulture Specialist
If you've ever seen a citrus tree while traveling in warmer climates of the United States, you've likely admired the glossy leaves and fragrant flowers. Although citrus plants are not winter hardy in the Midwest, some species can be grown successfully as indoor foliage plants and, given the right growing conditions, can even produce edible fruit!
You can grow citrus plants just for fun from seeds found in fruits purchased at local produce markets. However, these plants are generally not good candidates for long-term houseplants. Some of the citrus types best adapted to indoor culture include Ponderosa lemon, Otaheite orange, Meyer lemon, Persian lime and Calamondin orange.
Citrus foliage can adapt to the relatively low light levels typical of our homes. However, if flowers and fruit are what you're after, you'll need to give the plants as much light as possible. If natural light is inadequate, you can supplement with artificial lights. A combination of cool white and warm white florescent lights placed close to the plants will help, as will the special "grow lights" that emit the wavelengths of light most important for plant growth.
Relative humidity is generally too low in the typical home, especially during the winter heating season. Running a humidifier will increase both plant and people comfort. Pebble trays with water evaporating from the surface also can be helpful. Hand-misting is generally ineffective at raising relative humidity, though it can help wash dust off of the foliage.
Soil, water and fertilizer needs of citrus are similar to other houseplants. A good-quality potting soil mix with blooming-houseplant food applied according to label directions should be sufficient. Water thoroughly at intervals that allow the soil to dry just a little between waterings.
Citrus flowering is dependent on the particular species of plant, as well as environmental conditions. Generally, best success with flowering is achieved by moving the plant outdoors to a protected, partially sunny location after all danger of frost is past. Similarly, the plant will need to be brought back indoors at the end of summer, before temperatures dip below 50 F. However, unless the plants are gradually exposed to these drastic changes of environment, they will often respond by dropping many leaves and, possibly, flowers and young fruit.
If citrus is kept indoors year-round, the plants will likely need a bit of pollination assistance when they do flower. Use an artist's paintbrush or cotton swab to transfer pollen from one flower to another. You may need to consult a botany book at your local library to help you recognize the various parts of the flower.
If pollination is successful, fruits will develop, but can take quite a few weeks to ripen. It is not unusual for small, young fruits to drop off the plant shortly after they have formed, either from inadequate pollination or unfavorable environmental conditions.
The URL for this page is http://www.hort.purdue.edu/ext/citrus.html