Key limes, known botanically as Citrus aurantifolia and also commonly as Mexican lime, are small limes that are yellow instead of green when ripe. They possess a strong and distinctive citrus aroma that is tart and they are grown primarily for their juice. Key limes can be grown in containers indoors with sufficient light and air flow and can be planted out in the garden in USDA zones 9a through 11. Key limes bloom in May and then fruit through September each year.
Locate key limes trees in full sun to partial daily shade exposure. Provide at least six hours of daily sunshine for optimal performance. When growing key limes as an indoor ornamental, plant in a location that receives at least a few hours of direct sunshine each day and bright indirect sunlight for the balance of the day.
Plant key limes in moist, nutrient rich soil that is slightly acidic to slightly alkaline its pH between 6.1 and 7.8. When planting in containers, choose a quality potting soil that includes peat moss and perlite.
Feed key lime trees with a good quality granular or liquid citrus food. Apply according to the manufacturer's instructions over pre-watered soil to prevent burn and better absorption of nutrients.
Water the key lime so that the soil is uniformly moist throughout the year. Do not over water, as this can create root rot and attract white fly and mildew. The easiest way to gauge the need to water is to use your index finger as a dip stick in the soil. When the soil feels slightly dry, it is time to water.