Do you love Thai cuisine? If so, then you probably know the elements that go into a good Thai curry. And you can grow an essential ingredient in your own backyard. If you like stir fry and tangy lime zest, try growing a kaffir lime tree!
Although these trees are native to tropical Southeast Asia, it is very easy to cultivate them outside of that region. With a bit of a shift in the colder seasons, you can have kaffir lime all year round. Alternatively, you can skip outdoor growing altogether and grow kaffir lime indoors.
Citrus plants can be large in their natural habitats, but they easily maintain a small size under the right conditions. Your trees could be residents of a greenhouse or patio, or they can be grown indoors. Watch out for the thorns though!
Let's talk about what might be your new favorite potted plant or even your favorite tropical plant to grow in the southern United States.
Good products on Amazon for growing kaffir limes:
Quick care instructions
The kaffir lime produces aromatic leaves and bumpy limes. Source: Stratman2
|Common name(s)||Kaffir Lime, Makrut Lime|
|Scientific name||citrus hystrix|
|days until harvest||Varies after 3 years|
|water||1 inch per week|
|floor||Well-drained, sandy soil|
|fertilizer||Citrus pellet fertilizer 2 to 3 times a year|
|pests||Ants, cotton swabs, mealybugs, spider mites, leaf miners, whiteflies|
|Diseases||Smudge fungus, foot rot, citrus canker, Huanglongbing|
All about kaffir limes
Tiny flower buds prepare to bloom on a kaffir lime. Source: willsfca
Kaffir lime or Makrut lime (Citrus hystrix) originally comes from Southeast Asia. The word "kaffir" has been attributed to a racial slur referring to non-Muslim Swahilian-Africans stolen from their land during the slave trade in the Indian Ocean. The Kaffirs were also an ethnic group in Sri Lanka descended from Bantu peoples.
Due to recent changes in political views on common names, many restaurants and grocery stores are using the name Makrut lime. It turns out that micrantha — a term referring to a long-lineage lime tree — is the same species as C. hystrix. In the interests of compassion, many use the term makrut instead when referring to this citrus plant.
This citrus tree is an evergreen shrub that stands anywhere from 6 to 35 feet tall. The double hourglass-shaped leaves, with a leaf blade twice the size of the petiole, grow on thorny branches from a central stem. In spring, four- to five-petalled white flowers up to 2 inches wide bloom and are self-pollinating. They die off and green citrus fruits with a bumpy exterior shape where the bloom once was. The fruit ripens and forms a yellow skin. Home gardeners hand pollinate kaffir lime when grown indoors.
Crushed leaves give off an intense citrus scent and bring a delicious flavor to the kitchen. The fruit skins have an astringent flavor that is incorporated into a curry base paste. They are also made into spiced rum. The bark is not only used to add flavor but is said to repel mosquitoes, fleas and lice. The fresh juice of the fruit is mixed with water and used as a cleanser. Makrut essential oil is used in several industries, including aromatherapy.
Since this plant takes a while to bear fruit (at least three years from the sapling stage), many gardeners prune it to keep it small enough for a large planter. This is not an easy task due to the thorns, which can be up to 1.5 inches long. Some people even graft less thorny citrus fruits onto makrut to remove some of the thorniness in future growth, although this would produce a mixed fruit tree. It is also common to graft makrut branches onto another citrus rootstock.
Most people in the western hemisphere place their kaffir lime in a large planter that is at least three feet deep. The kaffir lime thrives in the tropics. If you live in a tropical region and grow other tropical plants, plant kaffir lime outdoors in late fall to give your tree time to root in the soil before the summer heat. Do not transplant in the middle of winter in cold weather or you will endanger the kaffir lime. Place it far away from other fruit trees and away from your home and amenities. Kaffir lime trees grow up to 35 feet tall in optimal conditions.
Dig a hole at least 3 feet wide and twice the width of the root ball. Change the soil inside the hole to include sand for drainage and well-rotted compost. Place the kaffir lime in the hole and then add average garden soil. Allow the tree mound to stay above the ground line, making sure no grafting sites are covered. If you live outside of the tropics, plant your kaffir lime from the plant pot in a large container with the same mix of soil that an outdoor tree would have. When the cold weather hits, your kaffir limes can then be brought indoors.
The thorns of a Makrut tree are no laughing matter. Source: moirabot
Let's talk about the basic needs and growing conditions of your kaffir limes. You will have a delicious harvest of kaffir lime leaves all year round.
sun and temperature
Makrut trees are tropical and need full sun. That means at least 6 to 8 hours of sun per day. The USDA hardiness zone range for these trees is small, ranging from 10 to 12. Kaffir lime leaves are easily produced in high temperatures. Triple digit heat is no problem at all. But if the weather drops below 50 degrees Fahrenheit, protect your tree. Bring it indoors or cover the aromatic leaves with a commercially available frost cloth. If it experiences a hard freeze, it can die. Low temperatures (below 50 degrees) also inhibit flowering and fruit production.
water and moisture
These plants love high heat and humidity. If you experience dry heat in your area and your tree is outdoors, water at the base of the trunk a few times a week. Do this in the morning and avoid wetting the foliage. Overall, about an inch of water per week with the right humidity level is sufficient. Allow the soil around the tree to dry out between waterings to avoid waterlogging. Drip irrigation or drip lines are optimal for watering, but any other gentle watering method will work. Don't water if it has rained a lot. Water a few times a week during the fruiting phase of the growing season to aid in fruiting and volume.
The soil around the tree should be average to fertile and sandy to encourage good drainage. Fill a pot or hole in the ground with a good mix of average garden soil supplemented with sand and well-rotted compost. Makrut can survive in poor soil, but most importantly it needs good drainage in the pot or hole where you place it. A pH of 6 to 6.5 is best.
After the first year of growth, fertilize Makrut 2 to 3 times a year with slow release citrus fertilizer. A few tablespoons are enough, even with old trees. Apply this in early spring, early summer and late summer. Do not fertilize in winter as this can shock the tree. The NPK of the fertilizer should be 2-1-1. Pour it well.
Wear strong, thick gloves when pruning this tree as it is thorny and will sting easily. use pruning shears. Always cut at the node of each branch unless you are partaking of the branch due to illness. Cut branches back a few inches if they display a weeping attitude. If you want to keep your tree small, it is important to prune it.
Begin by removing any diseased branches. Then remove any dead branches that are dark brown and dry under the bark. Scratch the surface of the branch to see if it's dead. Next, remove small sprouts from the bottom 10 to 12 inches of the tree. Save them as they can be propagated into new trees. Branches that grow towards the base of the trunk should also be removed. Note that Makrut is evergreen and leaves do not fall in winter.
Those little buds and suckers you cut off the tree can be rooted in a starter pot. Use a propagation dome and rooting powder or gel to help the stems get started. Cut the end of the cutting neatly and remove the lower leaves. Use quick rooters and insert the tip after dipping them in rooting media. Spread the cuttings out in your tray so they don't touch each other. Spray them with water and place the dome over the top of the tray. Put them in a place with little light. Keep the area at around room temperature. It can take anywhere from 6 days to 6 weeks for the cuttings to take root.
To graft your lime onto a different rootstock (this could be a different macrut or lime species), take a section of a healthy branch and cut a 45 degree angle along the base of the stem. Then cut off a branch of the rootstock, exposing the healthy flesh. Cut just enough into the rind to separate it from the meat and place the makrut cut under the rind. Tie them together with plastic and place a plastic bag around the grafted area and secure the edge to the rootstock. After a few weeks, remove and wrap the plastic bag. If the branches are fused and new growth emerges, you have succeeded.
Harvesting and Storage
Makrut limes have a characteristic bumpy skin. Source: smashz
Despite the thorns, the stings, and the pain, it's so rewarding to harvest this tree in your garden! Whether you choose aromatic leaves, fruit, or juice, you'll have year-round astringency to pack into your dishes.
Pick green kaffir lime leaves when the tree is mature, in spring when they are fresh. Toss them with your favorite fish, chicken, or hot, spicy foods as needed. If you want to pick a few leaves, hand picking is fine. For larger harvests, select an entire branch and carefully remove any leaves. Gloves are a must here.
The fruits set about 6 to 9 months after the flowers died. At this point, test a lime by removing it by hand and slicing it in half. If there is enough juice, the remaining limes should be done. Harvest the fruit when it is green, not yellow. The yellow fruits are too bitter to be used in dishes, although the peel is often added to dishes as a condiment. Harvest the fruit all year round in tropical areas. In areas outside the hardiness zones, harvest takes place in late summer.
Wash fresh leaves and store in a plastic bag with paper towels in the fridge for a week. In this way they freeze up to 1 year. To dry them, hang an entire branch upside down in a warm, dark, and dry place until they snap easily. Store them in an airtight container for 2 years.
Store fresh limes on the countertop with good air circulation for 2 to 4 weeks. They will keep in the fridge for 1 to 2 months. Sliced limes should be consumed immediately or within a day. Lime juice will keep in an airtight container in the refrigerator for 6 months. Freezing is not recommended as it will ruin the lime's texture, but freezing the juice is fine. The same goes for other citrus fruits like lemons. Dehydrate the lime until completely dry and it will keep in a plastic tub or glass jar for up to 5 years. Properly filled and sealed lime jars last 9 months. Freeze whole or sliced lime zest and store for 1 year. Use this bowl in dishes as needed and smell this delightful fragrance.
Container grown kaffir lime is definitely an option. Source: Andy Roberts Photos
Now we've covered care, so let's cover the issues to look for when inspecting your tree.
Grow this tree in an area that is too cold, and takes cold damage. At longer temperatures below 50 degrees, the tree can be damaged or die. Bring it indoors if you suspect the weather won't let up.
Growing the tree in a medium that does not have good drainage and stays wet for too long creates conditions that stress the tree and put it at risk of contracting a disease. If it dries up too long, the tree will drop leaves and flower slowly, slowing down your yield. ONE lack of nutrients will also slow yield and show up as changes in leaf color. Remember to fertilize 2 to 3 times during the growing season to avoid nutrient deficiencies.
ants are a sign that other pests might be nearby. They tend to harvest the honeydew of other pests like aphids. By domesticating these pests, ants have a food source… and so do the other pests. Mix equal parts borax, peanut butter, and honey into a paste and fill old bottle caps with it and place them around the base of the tree. The ants will harvest the paste, carry it back to their hive, and the borax in the paste will kill the colony. Paint the trunk of the tree with sticky paint like Tanglefoot Trap to prevent ants from reaching the fruit.
Padded cushion scale is a common problem in citrus trees. It looks like white fluffy bumps that appear on tree branches and trunks. However, it is not a fungus or a disease. They are insects – Icerya purchasi to be exact. They suck sap from twigs and can produce honeydew, which ants love to drink. If they are few, use a cotton swab dipped in rubbing alcohol to force them to detach from the plant and remove them. Neem or horticultural oil will effectively kill these scale insects and other mealybugs.
Mealybugs, spider mites, leaf miners and whiteflies are all insect pests that suck the sap from the leaves and branches of the Makrut tree. Mealybug look like small tufts of cotton that live in colonies in the tree. spider mites are so tiny that you may not see them until later stages when they spin webs around parts of your tree. leaf miners migrate into the leaves rather than onto the surface, and eat the flesh between the cell walls of the leaves. They leave little meandering tracks on their leaves. white flies are small moth-like insects that feed on the sap of trees in any location.
Look for these insects and blast them off with a powerful jet of water as quickly as possible. This usually fixes the problem. Neem oil is effective against the eggs of most of these pests as it causes the unhatched young to be smothered. It is also effective against adult spider mites. The citrus leaf miner is a little more difficult to treat; Remove leaves that show signs of mining and destroy them. Then spray the tree regularly with neem oil as the naturally forming azadirachtin in the oil will gradually permeate through the leaves to remove any remaining larvae. Insecticidal soap is effective against adult mealybugs and whiteflies.
Xanthomonas axonopodis pv. citri is the bacterium that causes citrus crab. Yellow ringed lesions appear on all parts of the tree (leaves, branches and fruit). In later stages, the lesions acquire a grey, fuzzy center and the tree becomes defoliated. Remove damaged parts of the tree as soon as possible. Apply copper fungicide spray according to the manufacturer's directions, making sure to cover all parts of the tree. It is important that you contact your local agricultural agency and let them know you are dealing with citrus canker as some regions have local regulations that force you to close the tree due to risks to other trees in the area fell and disposed of, and the disease is pursued. Copper fungicide is not guaranteed to cure this canker disease, so you could lose the tree regardless of trying treatment.
Greasy spot comes from the fungus called Mycosphaerella citri. It starts with a spot on the underside of the leaves that can form a yellow spot on the top that appears greasy and shiny in the center. It can also affect the fruit, producing dark spots called greasy spots on the rind, which are a significant agricultural problem for fruit sellers. Copper fungicides work to treat this fungus but are often mixed with horticultural oils before spraying.
Phytophthora gummosis is the causative agent of two soil-borne organisms that cause foot rot, or macrut root rot. You will notice cracked bark and gum in the cracks. You can see brown to black bark just above the roots. root rot caused by Phytophthora is difficult to treat. You can graft resistant rootstock onto your tree or use the methods listed for grease stain to treat foot rot.
Huanglongbing (HLB), also called citrus green, is a bacterial disease that affects almost all citrus plants. It causes new leaves to take on a mottled appearance and the fruit contains abraded seeds. The fruit must not ripen on trees affected by HLB. If you notice these symptoms on your tree, quarantine it and contact your local agriculture office. You have information about the best next steps.
frequently asked Questions
A cluster of newly forming Makrut Limes. Source: Thanh Coutts
Q: How tall does a kaffir lime grow?
A: Anywhere between 6 and 35 feet depending on the conditions.
Q: What is the difference between kaffir lime and lime?
A: Kaffir limes are bumpier, grow on thorny trees, and have a much more astringent smell and taste. The leaves are the most popular crop from this tree!
Q: Why are kaffir lime leaves so expensive?
A: Those are those damn thorns! The harvest must be done carefully so that harvest workers are not stabbed.
The green thumb behind this article: