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How to Grow a Key Lime Tree

Updated on December 11, 2017
OldRoses profile image

Caren White is a Master Gardener and instructor at Home Gardeners School. She has been a volunteer at Rutgers Gardens for over a decade.


Key Lime pie is most often associated with the Florida Keys but the main ingredient, key limes, are not native to Florida.

What are Key Limes?

Key limes are native to Southeast Asia. They are hybrids; a cross between two lesser known primitive citrus, papeda and citron. It is thought that from their homeland in Southeast Asia , the fruit travelled along the trade routes to the Middle East and then to North Africa and on to Spain from whence it was carried to the New World by the Spanish as they colonized the West Indies. From there, it was just a short hop to the Florida Keys. In modern times, the fruit is grown in Central and South America as well as tropical parts of the US including Florida, California and Texas.

The trees are hardy only in zones 9 – 11. Grown outdoors in a tropical climate, the trees will reach heights of up to 20 feet. They are multi-stemmed meaning they don’t have just one trunk. Rather they grow more like a shrub with multiple stems which are quite thorny. The flowers are approximately one inch in diameter and yellowish white with a faint purple tinge on the edges. The trees flower year round, but bloom most heavily from May to September.

Key Lime Pie that has not been artificially colored
Key Lime Pie that has not been artificially colored | Source

The fruit is harvested before it is ripe. Unripe fruit is green in color. When the fruit is fully ripe, which can take 6 to 9 months, it is yellow. Interestingly, key lime pies that are green have been artificially colored because it is made with the ripe fruit which is yellow. The rind on key limes is much thinner than ordinary limes and have more seeds. The flavor is stronger than ordinary limes.

Fortunately, there are now dwarf cultivars that are suitable for growing in containers so that those of us who do not live tropical climates can grow our own fresh key limes indoors or outdoors during the summer and indoors during the winter.

Key Lime Rind is thinner than regular limes
Key Lime Rind is thinner than regular limes | Source

How to Grow a Key Lime Tree

If you are fortunate enough to live in a tropical area, you can grow your key limes outdoors in the ground. Choose a sunny location and dig a trench. The root system on the trees is very shallow. Planting your trees in a trench allows the roots to gain more of a foothold and protects the trees from topping over when it is windy. Keep your trees pruned to allow for good air circulation and ease of harvest. Grown outdoors, the trees are self-pollinating.

If you live outside of a tropical area, you will need to choose a dwarf variety and plant it in a container. You can place the container outside during the summer in a sunny spot that is protected from the wind. The shallow root system, even in a container, makes them prone to falling over in strong winds. Bring your tree indoors before the first frost. Unlike outdoor trees which are self-pollinating, you will need to hand pollinate your tree indoors.

Whether grown indoors or outdoors, Key limes need to be kept moist. Do not allow the soil to dry out completely between waterings. They are heavy feeders. Use fertilizer that is specifically formulated for citrus during the growing season. Do not fertilize during the winter. You can also prune any time except during the winter.

Key Lime Flowers - they are self-pollinating outdoors but must be hand-pollinated indoors.
Key Lime Flowers - they are self-pollinating outdoors but must be hand-pollinated indoors. | Source

How to Propagate a Key Lime Tree

Hybrid plants do not normally grow true from seed. The Key Lime tree is an exception. It can be grown from seed. Use seed from a fruit so that it is fresh and moist. Clean off the pulp and plant it ½ inch deep in a container. Keep evenly moist. Germination should occur within two to six weeks. You can plant your seedlings outdoors when the daytime temperatures are above 70⁰F and the nighttime temperatures are above 55⁰F.

You can also propagate from cuttings or more drastically by cutting the roots of an existing tree which will encourage it to produce sprouts which can then be severed from the tree and planted elsewhere.

Trees grown from seed will start to bear fruit between 4 and 8 years old. Trees propagated from cuttings or sprouts should start producing fruit the following year.

© 2017 Caren White


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    • OldRoses profile image

      Caren White 4 weeks ago from Franklin Park, NJ

      Thanks Dianna! And thank you for reading and commenting.

    • teaches12345 profile image

      Dianna Mendez 4 weeks ago

      I do love Key Lime Pie and it is pretty popular here in South Florida restaurants. Interesting article on this tree and well written.