"Place your citrus plant where it will receive at least 6 hours of direct sunlight or preferably more (8 to 12 hours) each day. During the winter, a position near a South-facing window will provide the strongest light. Supplemental indoor lighting with a fluorescent or LED grow light will be necessary if ambient light is insufficient.

In the spring, after the danger of frost has passed, place your citrus tree outdoors to receive the maximum amount of sunlight – 8 to 12 hours of direct sun exposure – and move it back indoors in the fall, prior to the first frost. Acclimate your plant gradually when you move it outdoors/indoors. For example, move your plant to a partially shaded area outdoors after the last frost in spring, and gradually move it into more light over a period of two weeks.

Citrus plants like consistent moisture but not waterlogged soil. Choose a lightweight container that has a drainage hole in the bottom to allow excess water to drain out. Citrus plants in containers outdoors in the summer may need daily watering, depending on the weather conditions and the moisture-holding ability of your planting medium. When indoors, take care not to overwater your citrus plant. Check your plant’s soil moisture once or twice each week. Press a finger down 2 inches into the soil. If it feels dry, it is time to water. 

Thoroughly add water until it drains out from the bottom of the pot. Remove any excess water from the saucer or tray underneath; plants should not sit in standing water. Allow the surface of the soil to dry out between waterings. Fungus gnats can become a problem if the surface of the soil remains wet. Leaf drop is an indicator of overwatering. Flower drop is an indicator that the soil is too dry."

https://extension.umn.edu/houseplants/growing-citrus-indoors

https://extension.psu.edu/grow-your-own-lemons#:~:text=A%20sunny%2C%20south%2Dfacing%20window%20is,one%20tree%20to%20produce%20fruit.