How to Grow Key Limes in Containers

Growing up I had a huge backyard to run around and play in. I would stay outside with my friends until the sun went down and the huge mosquitos would come out. And even then we’d play until my mom would call me inside. There was a lot going on in that backyard, but it easily housed two huge grove-worthy citrus trees. Not every backyard has that kind of space, but luckily that’s ok. If you’re interested in growing citrus trees, but don’t have a lot of space, you can grow them in pots. There’s a lot of citrus fruit you can choose from to grow. Some of my favorites include Meyers lemons, mandarin oranges, and key limes. Here we’ll discuss how you can grow key limes in containers.

Citrus Growing Conditions

Citrus is a subtropical fruit that includes oranges, grapefruit, lemons, and limes. Unlike some fruit trees, most citrus is self-fertile, so only one tree is needed for the fruit to produce. On average, citrus trees begin to produce fruit once they’re 3-5 years old. Citrus also needs a certain level of accumulated heat to ripen. 

If you live in hardiness zone 8 or above you should be able to grow citrus without having too much of a problem. Citrus trees are very frost-sensitive and need to be protected or moved (if in pots) when there’s cold weather. If winter nighttime temperatures where you live are consistently below 35°F then you’ll need to be able to move your trees indoors. If you only have occasional cold temperatures, then you’ll want to cover your citrus trees with frost blankets.

Zones 4-11 patio / Zones 8-11 outdoors

Image Credit: fast-growing-trees.com

Key Limes

Florida is home to the Key Lime Pie, but ironically the tiny yellow fruit hasn’t grown here commercially for decades. Groves were commercially grown in the Florida Keys, and the industry peaked in the 1920s until 1926 when a hurricane wiped out the groves. They were never replanted. While the largest commercial producer of key limes is now Mexico, there are still a lot of Florida homeowners who grow their own key lime trees.

Key limes are different than Persian limes that are typically found at the grocery store. Key limes are smaller, roughly 1-2 inches in diameter. They are also round and yellow when mature. The peel is thin and smooth and the juice is more tart.

Image Credit: blogs.ifas.ufl.edu

The Key Lime is more cold-sensitive than other citrus trees due to how acidic they are and tends to be injured or killed when temperatures drop below 32°F. Key lime trees like well-draining soil and extensive periods of flooding can kill the tree. Grown in full sun, citrus trees need quite a bit of heat to set quality fruit. Fruit ripens about 5-6 months following flowering. Trees are small and thorny with small pale green leaves. The flowers bloom primarily in the spring, followed by summer fruit.

Grow Key Limes in Containers

You would grow key limes in containers similar to other citrus trees. There are a few things to be more aware of when growing in containers versus in-ground planting. Trees have more room to grow in the ground, however, sometimes there isn’t enough space to allow that, and container gardening can still give you the opportunity to grow some of the fruit you enjoy. Trees planted in containers will not become as large or produce as much fruit as trees planted in the ground. However, if you live further up north you’ll be happy to be able to bring them indoors when it’s cold outside. 

Selecting Pots

Citrus trees have wide, strong root systems that help them gather moisture in hot climates. Keeping this in mind, when you choose a container you should make sure it has a larger diameter to allow your tree to spread its roots at the surface level. Most tree roots are located in the top 6 to 24 inches of soil. A pot that is 28″ or larger in diameter should be used. Drilling additional holes in your pot might be necessary for drainage. If you live in an area that gets cold in the winter, consider how you will move the pot.

When planting your tree in your pot you’ll want to make sure you plant it at the original soil level. This will ensure that the graft union is above the soil line. Fruit trees are typically grafted to a rootstock, about 4″ to 8″ above the rootball.

Potting Soil

Potting soil should always be used for pots and containers. Regular soil compacts. Potting soil is different in that it includes material that allows for aeration and drainage. Materials such as perlite, vermiculite, or peat moss should be mixed into your soil.

Location

When choosing a location for your tree, you should select a spot that gets 6-8 hours of sunlight a day. They can tolerate some shade in hotter zones but thrive in full sun. Potted plants do enjoy a daily misting for humidity. Keep in mind that shadows are longer during winter months, so you’ll want to be mindful of how close you keep your trees to the south side of your yard.

Watering

You’ll want the top 2-3″ of your soil to completely dry out between watering. This can be anywhere from once a week to every day. Once the soil dries out on top, you should water until you see water escaping the drainage holes at the base of the pot. Citrus roots like moist but not soggy conditions. The watering needs of citrus will be different when they are in containers because roots will dry out more quickly. A moisture meter can help you determine when it is time to water.

Pay attention to the foliage. Wilted leaves that perk up after watering meaning you should be watering more often. If your leaves are starting to yellow or curl it could be a sign that you’re watering too much (though yellowing can also be a nutrient deficiency). 

Fertilizing

Trees grown in containers need more fertilizer compared to trees that grow in the ground because their environment is very self-contained. Although there are many varieties of citrus trees, their needs are about the same: nitrogen, phosphorus, potassium, sulfur, and calcium. Nutrients that are required, but needed in less abundance, include iron, zinc, magnesium, copper, molybdenum, manganese, chlorine, and boron.

The amount you apply will depend on the type of fertilizer as well as the size and age of the tree. Citrus grown in containers should be fertilized every other month during the growing season. Organic, liquid seaweed can be sprayed on the foliage on a monthly basis. Liquid seaweed spray contains 60+ trace minerals and also helps the tree to become resistant to disease.

Pruning

Any branches that start to grow below the graft union should be cut off because they will steal nutrients from the primary trunk of the tree. Dead branches should also be pruned. Citrus can be pruned for size and shape, but it isn’t necessary. The best time to prune is in the spring after the last freeze has passed but before new growth appears.

Instructions:

1. Preheat your oven to 350° F. In a food processor, pulse the graham crackers until they are fine crumbs. Add the melted butter and sugar and pulse to combine.
2. Press the graham cracker mixture into a 9-inch pie plate or tart pan. Bake the crust for 10 to 12 minutes, until golden. Remove from oven and let cool slightly.
3. While the crust is baking, whisk together the egg yolks, condensed milk, and Key lime juice until blended. Pour the mixture into the crust and bake for 15 minutes. Remove from oven and let cool.
4. In a stand mixer or large clean bowl, whip the egg whites until stiff peaks form. Add cream of tartar. Slowly add the sugar and whip until the egg whites are in stiff peaks. Spoon the meringue over the cooled pie filling.
5. If you want to toast the topping, use a kitchen torch to lightly toast the outside of the meringue or place it under the broiler on high. Watch it carefully! It will brown quickly.