A Mexican lime is a variety of lime tree that is better known as a key lime. Mexican lime trees produce fruit that are smaller and more flavorful than the commercially grown Persian limes that are found in supermarkets. The tree is extremely sensitive to cold weather. People who want to grow Mexican limes in USDA hardiness zones 8 or colder must grow them in containers and move them indoors in colder weather.
Select Mexican lime trees that have been rooted from cuttings or grafted onto root stock. Saplings such as these may be purchased from a nursery specializing in citrus trees. Although Mexican lime trees may be grown from seed, they will not produce flowers or fruit for up to nine years.
Purchase a container that is slightly larger than the root ball of the plant itself. A container that is larger than the plant will help you avoid repotting every few years, but a container that is too large will hold too much water and cause the roots of the plant to rot. In general, a 15-gallon container is large enough to accommodate a 3- to 4-year-old plant and allow it to grow up to 10 feet tall. If you select a smaller container and allow the tree's roots to become root-bound, the tree will remain smaller in size.
Select a potting soil that contains peat moss. Mexican limes prefer slightly acidic soil that drains well. Peat moss will provide the acid that the lime trees need to thrive and will not cause standing water that promotes root rot.
Place a pottery shard over the drainage hole in your container to promote drainage without causing soil to wash away. Fill the container one-third of the way full of potting soil. Place the roots ball of the plant into the container.
Fill the spaces around the root ball with potting soil and barely cover the roots of the plant. If the trunk is covered by potting soil, it will promote root rot. Leave less an inch of space in the top of the container for watering to prevent standing water in the pot.
Water the plant just enough to keep the soil moist. Check your plant daily by sticking your finger into the soil up to the second knuckle. Soil should feel only as damp as a wrung-out sponge and a few soil particles should stick to your skin.
Mist the leaves of the plant with water in a plant mister. This helps increase the humidity in your tree's canopy. This is especially important for indoor lime trees because the conditioned air of a house is very dry.