Citrus trees are subtropical or tropical plants, but many can handle temperatures down to freezing. In areas with sustained freezing or below-freezing temperatures, they need to spend winter indoors, where they can keep growing with proper care, according to Jessica Damiano. She grows Meyer lemon and Ponkan mandarin trees in pots in New York.
Damiano uses a well-draining potting mix made for citrus. She said good drainage helps keep roots healthy in winter, when the tree needs less water. She places her trees in the sunniest spot in her home, and said a south- or southwest-facing window is ideal. If sunlight is low, she suggested a full-spectrum grow light used 10 to 12 hours a day.
Citrus trees can be toxic to pets, Damiano said. She has a cat and a dog, so she keeps her trees out of their reach with a 4-by-3-foot mesh bag with a drawstring tie. The trees still get light through the mesh, though she said the mesh filters out some sunlight.