As a citrus tree, limes are unsurprisingly closely related to lemons, grapefruits, and oranges. These tart little treats are believed to have originated from the regions of southern Iraq and Persia and can now be found growing all over the world where sub-tropical to tropical climates prevail. Different varieties will vary in levels of acidity and flavor but generally make a great alternative to the more-sour lemon. If you don’t have a greenhouse or live in cooler climates than limes prefer, don’t fret. Dwarf varieties will grow quite well in containers which can be taken inside during cold weather. Take note that you will need to hand-pollinate if growing limes indoors.
The Key lime is a small, many-branched tree which produces 1–2″ fruits with a thin rind that turns yellow when fully ripe. Fruits often have seeds, and trees often have thorns. Although thornless varieties are available, they generally have a lower yield. The flavor is acidic and bitter. This is a good choice for container or indoor growing as trees can be pruned to stay under 6′ tall. White flowers will need to be pollinated by hand if grown indoors, and luckily, because they’re self-fertile, you will get fruit with only one tree.
Seed: Not recommended. It may take an average of 7 years to produce fruit when grown from seed. Additionally, because it’s a hybrid and rarely produces seed, it’s unlikely that any lime trees you grow from seed will be a true Key lime. But, if your curiosity is piqued:
Seed Depth: 1/2″
Space Between Plants: 6–25′, depending on whether you are growing a dwarf or standard-size tree.
Space Between Rows: 20–25′
Germination Soil Temperature: 60–70°F
Days for Germination: 14–28
Sow Indoors: 4–6 weeks before the average last frost date.
Sow Outdoors: After all danger of frost has passed and the soil has warmed to at least 55°F.
Vegetative: Usually propagated by grafting cuttings. This technique offers a stronger, disease resistant root stock for otherwise troublesome varieties. The timeframe to harvesting mature, juicy limes will be much shorter! You can also directly root stem cuttings in soil or a soilless medium, or try air layering on lower stems.
Grows best in a mild tropical to subtropical climate without hard frosts. If you can find a sheltered, sunny location to provide some protection, you can grow limes outdoors down to USDA Zone 8, but the tree will do better in warmer areas. Grow in a container in cooler zones, bringing it inside or into a greenhouse for the winter. Temperatures below 30°F will begin to cause damage to foliage and can kill trees.
Natural: Full sun.
Artificial: Grows well under HID lamps, particularly MH, but HPS and LED lights will also work. If you’ve got a fairly sunny indoor location and just want a small boost of lighting, fluorescent lamps will suffice.
Soil: Prefers a well-drained sandy to loamy soil. A pH of between 6.0 and 8.0 will keep plants healthy and nourished. Plants will not tolerate saline soil. Create surface runoff by planting trees on a mound.
Soilless: Start seeds in a soilless mix containing well-rotted manure, perlite, and vermiculite to provide container-grown plants with adequate drainage.
Hydroponics: Thrives in a media-based hydroponic system with drip irrigation. Use rice husks, vermiculite, or perlite as your growing media because of their good drainage properties.
Water: Requires moderate levels of water. Plants in containers will need more frequent watering. Soak deeply about once a week, but do not allow water to pool at the base of the plant. An evenly moist soil is best for fruit production, as drying out can lead to cracked fruit. Still, it’s better to underwater than overwater, as wet roots will slowly kill your tree.
Nutrients: Requires fairly high levels of nutrients. An organic citrus-specific fertilizer should be applied one to three times per year depending on soil fertility. Nitrogen is particularly important for citrus and should be applied if growth seems slow or leaves look yellowed. Use compost or other nitrogen-rich amendments if so.
Foliar: Will benefit from a foliar spray of fish emulsion, liquid kelp, or compost tea if leaves are looking yellowed.
Pruning: If your tree is grafted, prune any shoots that emerge from below the grafting point, as these are not the right kind of citrus! Prune the tips of branches in the first season to promote bushy growth. Each spring, remove any dead or leggy branches. Remove flowers from rooted cuttings or grafted plants in their first few years to encourage root development.
Mulching: Keep mulch at least 12″ away from the trunk of the tree.
Deficiency(s): An iron, zinc, or manganese deficiency all cause younger leaves to turn pale or yellow, particularly in the spaces between the veins. Determine the specific issue by getting your soil tested.
Companions: Grows well with ginger.
Harvest: Fruits may form any time of year, but production will be stimulated by warm weather and longer days. Cut or pull full-sized fruit when green or wait until they are fully ripe, when the skin turns yellow.
Storage: Fruit will stay fresh for several weeks in a cool pantry or a little longer in the refrigerator.
Fun Fact: The Key lime gets its name from the Florida Keys. The first mention of Key limes was in 1905, in an issue of Country Gentleman, where the fruit is described as “the finest on the market.”
Other Names: Key lime is also known as West Indian lime, Mexican lime, dayap (Filipino), manao (Thai), chanh (Vietnamese), limão galego (Portuguese), and tilleul clé (French).
Preserve: You can dry your limes, a common method used in Persian cuisine. They can also be pickled by mixing slices with salt or preserved by turning into a homemade marmalade. Dry the leaves to use as a seasoning.
Prepare: Lime is often used as a flavoring in dishes and drinks. The acidity of the juice can be helpful in marinades and in preventing browning of cut fruit like apples. Also, try a lime chutney, popular in Indian cuisine, or look for dessert recipes for Key lime pie.
Nutritional: Provides vitamin C.
Medicinal: Limes contain phytonutrients which are being investigated for their anti-cancer properties. Limes might also be helpful in the prevention of cholera, which may be due to some antibiotic properties of compounds found in limes. The vitamin C (a powerful antioxidant) content of lime is a good prevention against scurvy and is also helpful in maintaining eye health and boosting the immune system. As an anti-inflammatory, they can be helpful in preventing arthritis and maintaining heart health. Consuming lime juice may also be good for digestion.
Warnings: Allergies to citrus are possible, so consult with a doctor if you notice adverse reactions to the plant. Oils from the peel can cause phytosensitivity of the skin, meaning the sun may make your skin blister in areas that have been exposed to the oils.
You’ve obviously got to make pie with your homegrown Key limes at some point. We recommend giving these 6-Ingredient Mini Raw Key Lime Pies a try for a healthy, easy, and delicious option.