The only way to grow Kaffir lime in a cold climate is in a pot, either forever staying inside the house or moving it in and out when the weather permits. In a warmer climate, when Kaffir lime is grown in the ground, it’s a mid-size tree that can grow to 25 feet high and 6 feet wide. But it can adapt to live in a pot. One of mine, over 20 years old, has to be pruned twice each year to a manageable size (around 6′ tall) that I can put it back in our basement.
Annual pruning is an easy task. Getting poked here and there with very sharp thorns is expected. Feeding it well after a good annual haircut will keep it healthy. But, what’s more important than pruning is repotting.
Kaffir lime can be root-bound pretty fast since it’s a small tree being kept in a pot. It will not be happy having its feet bound for years… imagine Chinese foot binding. I repot mine every couple of years. The smaller ones is easy to do but the larger ones give me a back ache for a few days.
How to repot:
First, do not water the Kaffir lime for a couple of days. The potting soil should be on the dry side so it will be much easier to loosen the roots. Grab the main trunk and pull the whole plant out.
I just pull my smaller one, picture on top, out of its pot. This is only two years in this pot but the roots are already packed at the bottom. Though the soil is pretty dry, the roots still hold it in a pot shape.
Next, shake the soil off the roots. You can do it with your hands or use a trowel. Make sure not to damage the main root-the larger ones. Use a clean, sharp clipper to trim off the finer roots.
If you want it to grow bigger, you can put it in a larger pot with new soil. I keep my smaller ones in the same pot for five years then give them a little more room with a slightly larger pot. The twenty-plus year old, I put back in the same pot since that is the largest size I can manage without hurting myself. Both of the larger ones are still happy in their pots.
I put a couple of inches of new soil at the bottom, mixed with organic fertilizer, placed the Kaffir lime in, then added soil mixed with fertilizer around and on top. Use a small trowel to probe the area between the plant and the pot to make sure that new soil fills any air pockets. Water deeply. I water it and let it sit on a tray so the soil can absorb excess water back later on.
Use a clean clipper to trim damaged and dry branches. I prune it down to a desirable size and cut branches that rub against one another only after it starts to bud new leaves. I think root pruning is traumatizing enough so I wait for it to settle and get used to a new space first. But that’s just me.
That’s it. The Kaffir lime should be very happy for a few years before the leaves start to get smaller and take longer to sprout new leaves. That’s when it’s telling you that it needs to stretch it feet.
Petals and Wings 
I had this exact problem, last year I purchased a kaffir lime tree, it appeared to be grafted but well developed and bearing some fruits. Due to overwatering, improper potting soil (purchased citrus soil which holds moist too much) and armoured scale infestation, it barely survived the winter, it lost all of its leafs and many branches.
It started to grow again in spring after I finally succeeded in eliminating all pests, I repotted it in a 50/50 potting soil mix of white sand and compost + healthy bacteria (BioNova MicroLife). it is watering off better but still not ideal.
I put it ina large pot of 45 cm diameter and 40 cm high, now in full heat of the summer I give it 2L of water + nutrients (sunplant for citrus: https://www.sunplant.be/en/products/private-customer/44-sunplant-citrus ) + Ph- to make the soil more acidic as our rain water is too alkaline and the soil hence is too.
It is located in my greenhouse where temperatures rise sometimes to 42°C (107.6°F) when the heatwave reaches its maximum.(I live in Belgium, Zone 8 from what i read)
It started to grow new leafs but today it lost more than 6 of them, all o fthem which had spots from overwatering but it was still a frightening thing, when I look on the net it seems after one year the tree must regrow plentyfull, yet i feel mine is not. Hence I was the one trying to germinate those 20 seeds (ordered via amazon) that failed, since I wanted to try with a second tree, one that is not grafted.
I am now also trying cuttings, it seems to form minor roots, but it’s the 3rd cutting already so I’ll have to wait and see.
Here is a picture of how my tree looks like atm:
https://photos.app.goo.gl/sM5iru95Jpt7wwNx9
I was wondering if I am doing anything wrong in order to save this tree and give it a more prosperous future, because each time it grows new leafs, it drops a bunch of old ones and I end up with many empty branches.
Your Kaffir lime looks ok in the photo. I think, from what you describe, you water it too much. The leaves will start getting spots then drop. I leave mine on the dry side, except when I just repotted them. I don’t feed them with special food, just an organic fertilizer once a month.
As for the cutting as a way to propagate it, I can’t really say much about. I prefer ‘air layering’, has a better success rate.
Is it normal they have brief periods of growth and then do nothing for a while? It only grew leafs and branches on 2 moments this year and now it’s doing nothing again, the sun has also been causing a heatwave and it got a minor sunburn on the leafs (50°C in the greenhouse) but the stem is undamaged. but now temperatures have cooled down to 22 °C and clouded.
I reduced watering a lot and it seems happier from that, just not growing 😦
At this rate it will take 3 – 4 years before it is restored to its former glory and maybe bearing fruit on the condition it overwinters properly. My Key lime also just got hit hard by scale, I can’t keep up with these pests
Thanks for sharing this info, hoping to find help for my poor tree! My tree was doing well but was packed in a 5 gallon nursery pot. I recently repotted it using a 15 gallon fabric bag and very expensive Foxfarm Ocean Forest soil. About a month later, it’s dropped almost ALL of its leaves. I fear I may have left it too dry after reporting as I typically overwater and tried to avoid that! It’s had spider mites that I’ve controlled eel with neem oil. Does not appear to have them now. I did notice a black film on some lower leaves before they all dropped. Guessing it was just a bit of mold as it wiped away easily with a water rinse. I’m perplexed and so so sad. Not sure if I should prune back the branches now or just leave it alone. Any help would be greatly appreciated, I so love this tree!
Hi Sara,
It could be anything from too much water, insects or the new soil itself. I don’t know what’s compounded in your new soil, but Kaffir lime grows best in a slightly acidic soil. Also, if the new potting soil is not completely composted it will draw nitrogen from its surroundings and away from your roots to continue composting. Some organic potting soils also add fertilizer mixed in that can burn the roots. I only purchase potting soil and leave the bag sitting for replanting the following season, use the oldest one first, and always mix them with the soil from old pot. Except if there is a suspect disease. If you think your new potting soil is good we can look at your plant. You mentioned ‘black film’ on the lower leaves. That’s a sign of mold that grows on sticky ‘honeydew’ that either aphids or scales secreted. You sprayed your plant with Neem oil to get rid of mites and aphids as well. Scale, on the other hand, is difficult to get rid of. You can hardly see them since they blend in well with stems. They attached themselves to the stems and under the leaves. They suck the juice out so the leaves starve and drop. Insecticide doesn’t usually work on scale because they have a protective wax coating, especially the adult ones. I don’t know how big your tree is but I would look at the branches and leaves and manually remove them. Rubbing alcohol on Q-tips works well or picking them off with your fingers. If your tree is still outside, you may see ants on the branches. That is a solid indication of scale infestation. This type of ant eats the ‘honey dew’ produced by the critters. I don’t kill the ants. I use them to point out where the scales are. The ants will be gone when scale is gone and there is nothing to eat.
You could cut the branches that look really dry. Of the ones without leaves, the leaves will grow back once the surrounding condition is good. All of mine drop a lot of leaves toward the end of every winter (inside the house) but grow them back fully once they’re outside. I removed as many scales as I could and left the rest for the birds and other beneficial insects to pick off.
I hope this helps. Good luck with your tree.
P&B thanks for your help. I haven’t testing the new soil but will this weekend, great suggestion!
No ants at all, no honeydew present and very limited mold – that I’ve wiped away. It’s now dropped every single leaf, and the branches are quickly turning from green to brown. I went out to inspect again, having seen no evidence of pests previously, and tonight I noticed tiny round raised reddish fonts on the underside of the lowest branch. Scraped them off with my fingernail but they are so small I cannot describe in more detail. Only spotted on lower branch but if it is scale, as you mentioned, they might be very difficult to spot.
With this new info I guess there’s not much to lose so I’ll prune dead branches this weekend and use alcohol on a q-tip as suggested. I’ve never had such trouble with pests! My covid distraction didn’t work I guess, super sad for this loss. ☹️
That sounds like too much water, if the red spots you scraped off feel like crystalized resin it’s from rootrot.
The only cure is to let the soil dry out , measuring with a cheap moisture meter from Amazon until it is in the red.
Then only give it a tiny bit of water because too much will then instantly kill it
It can take 4 weeks or more until the plant recovered.
Treatments with fungicide I do not recommend because they require to water the plant and wash the roots with the stuff, which is very stressful so don’t do this.
Do prune off the dead branches, because they’re part of the cancer, so to speak.
I put my (5yr old) kaffir lime tree outside in temperature above 100+degrees Fahrenheit (Las Vegas, NV) for two weeks and now it looks dead. The branches look all dried up and brown. Is it too late to salvage it?
I’m sorry about your Kaffir lime, but I think it may survive. Inside plants conform to light and temperature. When you take them outside for the first time, you have to introduce them slowly. I think that’s how your Kaffir lime become sunburned. If the leaves are burned but still attached, new leaves will emerge. If the leaves fall off but most of the stems have not dried up, it will come back but will take longer. You should hose it down completely. make sure there is enough water in the pot. Best to let it sit in water for 30 minutes to ensure that the roots at the bottom are watered, then lift the pot to let the water run off. Keep it in semi-shade until it starts to recover.
A five year old Kaffir lime is hard to kill.