By Amy Simone, Extension Master Gardener, University of Vermont
Imagine having sunny orange, bright yellow, and luscious green fruit growing in your home, especially during this gray, cold time of year. While we do not associate citrus plants with our northeast climate, several varieties can be grown as indoor/outdoor houseplants.
Citrus plants, native to Southeast Asia, have been cultivated for over 4,000 years. Their fruit is actually a type of berry with a leathery rind called a hesperidium. They are found in tropical and subtropical regions that offer warmth, lots of humidity, and sandy, slightly acidic soil.
Citrus fruits need consistently hot temperatures to produce sugar, which our climate does not offer. Therefore, sour citrus fruits such as lemons, limes, and small orange varieties like Satsuma and Calamondin are among those best suited to growing as houseplants.
Citrus trees can grow to 20 feet in their natural environments, which is certainly not manageable as a houseplant! Thankfully, there are dwarf varieties like tangerine (Satsuma orange), lemon (Ponderosa or Meyer), kumquat (Fortunella species), citron, and Calamondin orange. These will reach a more reasonable height of 3 to 5 feet.
Plant your citrus in a well-draining pot filled with cactus or citrus soil mix, or use regular potting mix amended with perlite. Fertilize with a high-nitrogen fertilizer formulated for acid-loving plants, and only while the plants are actively growing and flowering, generally from April through October.
In the winter, place your citrus plant in a sunny south-facing window away from cold drafts and ensure it receives at least six hours of direct sun daily. Supplement with artificial light if needed. Wipe the leaves periodically to remove dust—group several houseplants together to create more humidity, or run a humidifier near your citrus plant.
As temperatures consistently reach above 50 degrees Fahrenheit in the spring, gradually move your citrus plant outdoors, protecting it from direct sun at first. After a few days, place it in full sun and pay attention to its watering needs, which will be more frequent than when it was indoors.
Depending on your citrus variety, you may get flowers only in the spring or spring to fall. Dwarf citrus varieties are mostly all self-fertile, meaning that you do not need a second plant for pollination to occur.
You do, however, need insects to pollinate the flowers. If your citrus plant is indoors during flowering, you get to play pollinator. Use a clean, dry paintbrush or cotton swab to collect pollen from one flower and rub it on another.
In the fall, acclimate your citrus gradually so that it can move back indoors before the outside temperatures drop below 40 degrees Fahrenheit.
Don’t be alarmed if your citrus plant sheds some of its baby fruit. Potted plants cannot support that much fruit and will naturally shed the extra. However, fruit drop is also associated with temperature extremes, so take care to avoid those.
Dropped leaves are the plant’s response to overwatering. Flower drops will occur if the soil becomes too dry.
Most importantly, add a little patience to your citrus care routine, as young plants may take years to flower and produce fruit. Lemons and limes can take six to nine months to ripen, and oranges can take up to a year. Those colorful and delicious fruits cheering up your home will be worth it.
