Plant Palette

Plant Palette

Key Limes

Photo of Jennifer Schultz Nelson

Jennifer Schultz Nelson
Extension Educator, Horticulture

I was fortunate to have an opportunity to visit Southwest Florida recently, and escape the blustery cold of central Illinois for a few days. Without a doubt horticulture is a horse of a different color to someone like me from the Midwest. Instead of U-pick apple orchards, there are U-pick citrus orchards. Many people have a citrus tree or two in their backyards.

A popular dessert on menus wherever we went was key lime pie. If it weren't for a graduate school classmate of mine that hailed from Georgia, I would still think that the "key" in key lime pie was only a geographical reference to the southern tip of Florida.

I remember the day my grad school friend was so excited that she could finally make a real key lime pie thanks to the helpful produce department man at the local grocery store who special ordered the limes for her. I was completely confused. What kind of a grocery store didn't carry limes?

That's when my friend looked at me in shock and horror and explained that these were key limes, not just any old lime. Still confused, she explained that they were entirely different than what Northerners called limes.

What I knew as a lime is technically a hybrid lime known as a Persian or Tahiti lime, developed sometime in the late 19th or early 20th century. It is large and seedless, and picked while still immature, accounting for the bright green color I associate with limes. If they were allowed to mature and ripen, Persian limes would in fact be more yellow than green.

If I didn't know any better, I would have thought key limes were some sort of miniature Persian lime at first glance. They are about the size of a golf ball, and more yellow green than bright green. However, inside they are loaded with seeds, unlike their hybrid cousin.

But the big difference where key lime pie is concerned is the flavor. Key limes are much more sour than Persian limes, and there are other subtleties in taste that make them the preferred ingredient for many chefs.

So if their flavor is better, why aren't key limes the more common lime to find at the grocery store? The answer is very similar to that of other crops like tomato, where ease of production wins out over flavor. It turns out that though key limes taste better, they are harder to produce and ship to market.

Key limes used to be 'the' lime that everyone consumed. They are native to Southeast Asia, and historical accounts link their travel westward first with the Arabs, then with the Crusaders. Christopher Columbus is credited with introducing them to the West Indies, which most of us commonly refer to today as the Caribbean. They also are commonly called West Indian or Mexican limes.

It was very common to find commercial groves of key limes in Florida until a hurricane wiped them out in 1926. Around this time the hybrid Persian limes were gaining attention. They were thornless and could tolerate much colder temperatures than key limes. Besides this, they have much thicker rinds, making them more durable and easier to ship long distances. Unfortunately, flavor took a back seat to streamlining production.

Key limes are still found in south Florida and other warm climates, though they are more likely to be found in a backyard than a plantation. There is still some commercial production in areas other than Florida. This may increase somewhat as consumers demand not only produce year round, but produce with superior flavor as well. There are other lesser known types of limes around too, which may see some increasing demand as chefs demand authentic and exotic ingredients for different ethnic cuisines.

According to the legend, key lime pie was a true demonstration of necessity being the mother of invention. Before 1930, there was no source of fresh milk, ice, or refrigeration in the Florida Keys. They did however have sweetened condensed milk. Though no one wrote down a recipe until the 1930's, historians believe that the recipe for key lime pie was developed sometime in the late 1800's, and over time it became so popular that it was something every one "just knew" how to make. Like a lot of foods, everyone has their own opinion on what constitutes the "best" key lime pie.

Home gardeners lucky enough to live in warm climates continue to plant key limes as part of their landscape. Those of us in drastically colder climates like Illinois are not out of luck though. There are dwarf varieties available that are suitable to be grown in large pots that can be brought indoors for the winter. In line with my addiction to all things plant related, I saw one of these dwarf varieties for sale in Florida and somehow it snuck into my carry-on. With any luck I'll be harvesting key limes in central Illinois in a few short years!

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