Miniature, or dwarf, citrus trees make good houseplants that will supply your family with nutritious fruit such as oranges, lemons and limes. Although small varieties of citrus can grow larger than you might expect, you can prune these fruit trees to the size that you want and still expect to harvest some fruit. Indoor citrus trees need plenty of light, so keep yours near a south-facing window and set up fluorescent grow lights if your natural light is insufficient. If you want, you can move your miniature citrus tree outdoors for the summer to ensure that it gets lots of sun.
Plant your miniature citrus tree in a large container that has a drainage hole. Choose a decorative pot if you like, but use only containers that are 12 inches in diameter or larger. Fill your container about one third full with acidic potting soil, remove the young citrus tree from its nursery pot and then place it on top of the soil in the bottom of the pot. Fill the pot with more soil, making sure not to bury the trunk or the grafted portion of the trunk, which is usually about 2 inches above the plant's root system.
Water your newly planted citrus tree thoroughly until water seeps from the pot's drainage hole(s). You'll want to keep your citrus tree on a plant saucer to protect your carpet or wood floor, but don't allow water to remain in the saucer for more than a few hours to prevent root rot. You can use a turkey baster to suck excess water from the saucer.
Keep your miniature citrus tree in a spot where it will receive filtered sunlight most of the day. The larger your container, the more light your tree can withstand. Organic Bouquet advises, "A location that provides morning sun or filtered light throughout the day is ideal. In general, the larger the container, the slower the soil will dry out, and the more sun your tree will tolerate." Hang a fluorescent shop light or grow light above your tree if you are unable to provide your tree with sufficient natural light.
Water your miniature citrus tree every day during hot weather, but never allow it to sit in constantly wet soil. If you poke your finger into the soil, check for moisture 3 to 4 inches deep---when it feels dry, water your tree. Water your tree less frequently during cooler weather---only when the soil becomes dry to the touch.
Fertilize your miniature citrus tree with a plant food designed for citrus trees every third time you water it. Mix your plant food with water according to label instructions.
Prune your miniature citrus tree to keep it small and manageable. Avoid cutting off flowers or forming fruit to ensure a good harvest.
Repot your miniature citrus tree to a larger container every two to three years. After you remove it from its old pot, trim away about one third of the roots to encourage new, healthy growth. Discard the old potting soil and start fresh with a new bag of acidic potting mix.