During the warmer spring and summer months, your tree will be happy outside in an area that receives a few hours of direct sunlight a day.
Murphy explains that while some varieties of citrus trees (like grapefruit) are more tolerant of the cold, you’ll always want to bring your tree indoors once temperatures drop below 32 degrees Fahrenheit. Inside, you should place it right next to your sunniest window: A southern or western facing one would be ideal. If your home doesn’t get much sunlight, placing your tree under a grow light is also an option.
The next thing to consider is humidity: “I’ve found that the biggest issue with growing a citrus tree indoors is that our indoor environments tend to not be as humid as outdoor environments,” Murphy says, adding that you shouldn’t place yours next to heaters or AC units, which tend to dry out the air. Instead, pop it next to a humidifier or mist it daily to mimic the lush, tropical climate it evolved in.
Once outdoor temperatures are consistently above freezing for the year, you can move your tree back to its rightful place outdoors. If it’s been a long winter, you can reacclimate it by bringing it outside in the sun during the day and back inside at night for a few days.
This will involve a fair amount of lifting, so Murphy suggests placing your tree in as light of a container as possible. While ceramic pots may be pretty, they’re not the best option here. A galvanized metal can or fiberglass planter will prove easier to maneuver throughout the year.