Citrus fruits need warm, sunny winters to thrive. The hardiest citrus tree won't survive past USDA Zone 7; Ohio is in Zones 5a to 6b, thus making it impossible to cultivate citrus outdoors. But you can grow citrus trees as indoor foliage plants and produce delicious fruit. While not every variety works as a container plant, many do well when given proper care and adequate sunlight. If you don't have a south- or west-facing window for your tree, supplement with artificial lights, combining cool and warm white fluorescent bulbs.
Oranges and Grapefruits
Many unique and dwarf oranges and grapefruit varieties will grow indoors. The calamondin (Citrofortunella microcarpa) is a mandarin with lush, wide leaves and bright orange (though sour) fruits that resemble tangerines. The mandarin Blanco (Citrus reticulata) needs less heat to ripe than true oranges, and its fruit is very sweet. The Oroblanco grapefruit (Citrus paradisi x C. maxima) is a cross between a grapefruit and a pomelo, a mixture that means the fruit doesn't need a lot of heat to become sweet.
Limes and Lemons
The brightly colored leaves and fruit of limes and lemons are a pleasure in the cold winter months. Choose a Kaffir lime (Citrus hystrix) for its bumpy yellow fruit and delicious leaves, which are used in southeast Asian dishes. The Meyer lemon (Citrus meyeri) is one of the most popular citrus fruits grown in containers. It will produce a big harvest of deep yellow, slightly sweet lemons, and it's very easy to grow.
According to Purdue Extension, kumquats have been called "the little gems of the citrus family." The Meiwa kumquat (Fortunella crassifolia) has round, sweet fruits that taste delicious right off the tree. The limequat (Citrus aurantiifolia x Fortunella crassifolia) is a cross between a kumquat and a Key lime. It produces egg-sized, clear yellow fruit. The limequat can stay on your patio longer than most citrus; it is cold hardy to the mid-20-degree Fahrenheit range.