Although northern New England lacks Florida’s semi-tropical climate needed to produce citrus fruits as an outdoor crop, it is possible to grow oranges, lemons, grapefruits, kumquats, and other citrus varieties as ornamental indoor houseplants. The key ingredient to success is patience although you also need the proper lighting and temperature. Even then–not to discourage you–there’s no guarantee that your plants will produce fruit.
You also need to be aware that citrus plants grown from seed may not yield the same varieties as the original plant although I find that waiting to see what you’ll get makes it all the more interesting. Most commercial varieties are grown from cuttings and are often grafted as well to ensure the right variety.
As it may take six or seven years, even longer, for citrus grown from seed to bloom indoors, one way to shorten the waiting period is to buy a plant from a reputable garden center. Or take cuttings from a plant that you know has flowered and fruited in the past.
But let’s say you want to grow your own plants from seed. Where do you start?
First, you need a good soil mix of half peat moss and half perlite or sand, and a small pot or flat, if you want to start several seeds to increase your chance of success. Container size isn’t that important as you will need to replant in small pots once your seeds sprout and start to grow.
Use only fresh seeds, and plant at a depth two times the largest dimension of the seed. If you are planting more than one variety, label containers so you don’t get them mixed up. Water thoroughly, then cover loosely with clear plastic wrap.
Place in a room with 70 degree F temperatures until the seeds germinate (in about three to six weeks). Then remove the plastic, and move the container into bright light. Avoid direct sun as this could burn the tender young plants.
Once the seedlings have several sets of leaves, transplant into individual four- to six-inch pots filled with a sterile potting soil. Fertilize with a dilute potassium fertilizer, according to manufacturer’s instructions, repeating the application every two to four weeks. Don’t overwater, but do keep the soil slightly moist. Your plants will need about four hours of direct sunlight daily and temperatures between 60 and 70 degrees F. A window with a south or west exposure is best.
As your plants grow bigger, they will require pruning in early spring to prevent leggy branches and encourage new growth. Repotting in the next larger size pot every spring will help promote fruiting. During the winter months water sparingly, stop fertilizing, and keep the plant in a warm, draft-free place. You also need to check for insects. Plants grown indoors are particularly susceptible to mealybugs and spider mites.
Ripe fruit may be too tart to eat raw, but it can be made into delicious jams, jellies, or fruit drinks. But even if your plants never produce fruit, don’t despair. Your efforts were not in vain. Citrus plants with their glossy leaves and fragrant flowers are sure to brighten up any room in the house.
By Dr. Leonard Perry
Extension Nursery and Greenhouse Crops Specialist University of Vermont