Key Limes in San Antonio

By Mary Cennamo, Bexar County Master Gardener

Photo credit: Mary Cennamo

When I moved into my house twenty years ago, there was a small lime tree. The trunk had a diameter the size of a pencil. It was planted on the south side of our house along the fence line, which I thought would be fine, as it was the warmest part of our yard with the house serving as a barrier to block the cold northern winds. The first winter, when we were expecting a freeze, I did everything you should do to protect plants from the harsh temperatures. I watered it before the freeze, covered it with blankets, and gave it a light to provide extra warmth. It still died. I replanted without success for the next two years.

Twelve years ago, I went through the Master Gardener Training Program. In the years since, I have taken many citrus classes as part of my continuing education for the program. I know a lot more now about growing citrus in San Antonio!

Three years ago, I decided to try growing lime trees again. This time with much more success!

Key lime trees are grown in Florida from where they get their name “key” lime. They are also grown in the warmer parts of California. And they are grown year-round in Mexico, which produces most of the key limes found in our grocery stores. Key limes are also known as Mexican limes. The fruits are small and round with a tart flavor that is especially good in making pies and drinks. 

The biggest challenge to growing a lime tree in San Antonio is our winters. Lime trees are very susceptible to cold temperatures. While I have found that you can protect lemon trees in-ground from freezing with blankets or a portable greenhouse made of PVC pipes, lime trees are much more sensitive to the cold.

The trick is to grow them in containers.   

This time, I bought two larger trees to begin with so that they had a good root system started.  As the roots filled the pot, I moved them to a larger container to give their root system room to grow.  They are now in 25-inch diameter pots.  Citrus trees take 3 to 5 years for fruit production, and after three years, I am finally getting limes! I bring the trees in for the winter, or I should say, my younger son brings the trees into the garage when the temperature is headed below 40°F. They are occasionally brought out of the garage during the winter for some much-needed sunlight. If you put them on a three-wheeled plant stand, it will make them easier to move. Around March 1, they are brought back outside for the spring.

The AgriLife Extension recommendation is to fertilize container-grown fruits each month during the active growing season with a water-soluble fertilizer, used according to label directions. A deep green color of mature foliage is what you are looking for. Proper watering is important. The soil should be moist but not soggy. Citrus does not like wet feet! Water when the top inch of the soil is dry. I also mulch the containers after the weather warms up, to help conserve moisture in the summer and to keep the roots cool. 

If you see sooty mold on the leaves, check for pests like aphids and scale. You can use an insecticidal soap to control the aphids and horticultural oil for the scale.

Don’t let summer end without a piece of key lime pie! 

Key Lime Pie


Graham cracker crust:

1 ½ cups graham cracker crumbs

1/3 cup granulated sugar

6 tbsp butter melted

Key Lime Filling:

28 oz sweetened condensed milk

½ cup light sour cream

¾ cup key lime juice

zest from 2 regular limes or 4 key limes

Whipped Cream Topping:

1 cup heavy whipping cream

1/2 cup powdered sugar

1 tsp vanilla extract


Graham cracker crust:

Preheat oven to 375°F.

Mix graham cracker crumbs, sugar, and butter in a small bowl. Press the crumb mixture into an 8″ – 9.5″ pie pan. Bake for 7 minutes. Cool for at least 30 minutes.

Key Lime Filling:

Preheat oven to 350°F

Whisk together sweetened condensed milk, sour cream, lime juice, and lime zest in a medium bowl. Pour into prepared graham cracker crust and bake for 10 minutes.

Let pie cool slightly before chilling. Chill for at least 3 hours.

Whipped Cream Topping:

Beat heavy cream and sugar together in a mixer until stiff peaks form. Beat in vanilla. Spread or pipe the whipped cream on top of the cooled pie. Top with additional lime zest if desired.