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Growing the Exotic Kaffir Lime

Updated on August 19, 2016

Kaffir (or "Leech") Lime

Many years ago, while killing time waiting for a medical appointment, I found myself with an growling tummy and an hour to kill.

Happily, there was a restaurant right across the street. As luck would have it, the special for the day was Green Thai Curried Shrimp. It was love at first bite.

Thus began a decade-long devotion to Thai curries, and Green Thai Curried Chicken in particular. Most recipes call for a few chopped Kaffir Lime leaves. I was able to obtain a hefty bag of them from a local Oriental market - they were frozen, and I was told they would keep for a long time.

Nothing, however, beats fresh when it comes to cooking, so I promised myself that "one of these days" I'd buy a Kaffir Lime tree and have fresh leaves available. It as actually 12 years before I finally got around to it :-(

When I did, I hadn't given much thought to sprouting tropical limes in Western Canada...

Hardiness Zones

Vancouver Island lies within hardiness zone 5, which presents a challenge when sprouting tropical limes. Folks in warmer zones are probably wondering what all of the fuss is about :-)
Vancouver Island lies within hardiness zone 5, which presents a challenge when sprouting tropical limes. Folks in warmer zones are probably wondering what all of the fuss is about :-)

Importing Seeds - I'm always amazed at the things one can find on eBay...

Kaffir Lime Seeds
Kaffir Lime Seeds

After searching in vain for months, I came to the conclusion that tropical Kaffir Lime plants simply weren't available in my area. That led me to eBay, where I found a rich selection of seeds. I ordered twenty from a Thai vendor who offered a great price.

To my amazement, the seeds arrived in less than a week, and the dealer provided me with extensive information about how to germinate them successfully.

I was excited that I could try germinating them during the summer months, when the temperature in my solarium often exceeded 100 degrees.

Preparing the Seeds - They need a good soak before you plant them...

The seeds need a fair amount of time for germination, which can occur from 15-35 days, depending upon the temperature. The seeds have a thick skin, and need a bit of help before they're planted. I soaked mine a few hours in a bit of warm water, and then left them between wet paper towels overnight, hoping to soften the seed's shell a bit.

One side of the seed is (more or less) flat to concaved, while the other is more of a convex curve. My Thai supplier suggested seeds be planted convex side down, as it would help them germinate faster.Whether this is true or not I cannot say, but I took his advice and planted them as he suggested.

Planting the Seeds

There are as many ways to plant these seeds as there are stars in the sky, but I tried to follow my supplier's suggestions (there's a link to them at the bottom of the page) on the assumption he knew a lot more about these seeds - and how to grow them - than I did.

Because I was told that the germination rate was about 50%, I decided to plant 3 seeds each in small pots. I was in a hurry, so used a standard potting soil mix rather than the specific mixture he suggested.The only real difference was the sand content, and the drainage it would have provided, but I didn't think it would matter too much.

Germinating the Seeds, Round One

Kaffir Lime Sprout - the only one from nine seeds.
Kaffir Lime Sprout - the only one from nine seeds.

Germinating Kaffir Lime Seeds: Round One

I planted 9 well-soaked seeds in 3 small pots, and placed them in a bright spot in my home's solarium, which I hoped would be hot enough to facilitate sprouting - the usual daytime termperature was 85-95 degrees F.but fell overnight to the 50s. My supplier in Thailand suggested that the seeds would do best in a 100-degree environment, so I didn't know what to expect, although I was prepared to be patient.

The first seedling popped up after 5 weeks, so patience is indeed a virtue where Kaffir Limes are concerned. Unfortunately, only one seed of 9 sprouted, presumably because the environment was not warm enough to encourage germination.

2-3 Foot Kaffir Lime Tree in Grower's Pot
2-3 Foot Kaffir Lime Tree in Grower's Pot

If you don't like puttering around with seeds and seedlings, buying a mature plant is obviously attractive. I have not located a Canadian supplier for these plants. This listing is from Amazon.com

 

Germinating Kaffir Lime Seeds: Round Two

For the second attempt, I decided to create an environment where the temperature could be controlled. Happily, the Proofing Box I use for making sourdough breads was handy - it's crude, but it works :-)

I connected the proofing box to a timer, set to provide light and heat for 12 hours a day, and set the heat to 100 degrees Fahrenheit.

I cut down an old cardboard box and lined it with heavy duty aluminum foil. The seeds were placed within a fold of paper toweling, and enough water added to keep the seeds well soaked for 24 hours. The tray was then put inside the proofing box to warm and soak the seeds prior to potting them.

Germinating Kaffir Lime Seeds, Round Two

An inexpensive foam cooler was used to make the proofing box, along with a lamp socket and fader to manually control the temperature.
An inexpensive foam cooler was used to make the proofing box, along with a lamp socket and fader to manually control the temperature.
A digital thermometer displays the temperature on the right.
A digital thermometer displays the temperature on the right.
Quick & Easy Tray made from cardboard box and foil. A plastic tray would have been faster, but I didn't have one of the right size handy.
Quick & Easy Tray made from cardboard box and foil. A plastic tray would have been faster, but I didn't have one of the right size handy.
Kaffir Lime seeds.
Kaffir Lime seeds.
Kaffir Lime seeds.laid out on a paper towel.
Kaffir Lime seeds.laid out on a paper towel.
The paper towel is folded over the seeds, and soaked with water.
The paper towel is folded over the seeds, and soaked with water.

Germinating Kaffir Lime Seeds: Expanding Peat Pellets

Once the seeds had been soaked overnight at 100 degrees, they were transferred to expanding peat pots (photos below) and returned to the proofing box.After the pots have expanded, the seeds will be pushed into the peat.

The seedling shown in the top photo is the sole survivor of my first germination attempt...believe it or not, it simply stopped growing when Fall arrived; I'm hoping the stable heat will jump-start it.

The thoroughly soaked Kaffir Lime seeds are placed into expanding peat pellets and water added.
The thoroughly soaked Kaffir Lime seeds are placed into expanding peat pellets and water added.
Kaffir Lime seeds placed on expanding peat pellets
Kaffir Lime seeds placed on expanding peat pellets
After the peat pellets have expanded, the seeds are pushed down into the peat.
After the peat pellets have expanded, the seeds are pushed down into the peat.

How To Use Peat Pellets

Now we wait...

In my first attempt to germinate these seeds, only one seedling appeared...after a full month. I'm hoping the combination of consistent light and heat will prove more successful.

Now we wait.

Presto!

Sprouting seed exposed after nearly seven weeks - patience is clearly the watchword.
Sprouting seed exposed after nearly seven weeks - patience is clearly the watchword.
Day Three
Day Three

In Retrospect

It is interesting to me that this plant really responds to high temperatures. If I leave a sprout in the proofing box, it will generate new growth almost daily. If I remove the young plant from the proofing box and place it in my solarium (where the average temperature is well below 70 degrees), all visible growth stops.

My first plant (see "Germinating the Seeds, Round One") simply stopped growing when exposed to cooler temperatures. The photo in "Germinating Kaffir Lime Seeds: Expanding Peat Pellets" shows my first sprout at one year - it looked almost exactly the same one month after germination.

I have germinated seeds from Thailand and Ceylon. There doesn't seem to be any difference in the results, which have been disappointing. Germination for the Thai seeds was a dismal 5%. I have now planted 20 Ceylonese seeds, but results won't be known for another month.

I can't help but feel I'm missing something here - if you have experience with these plants, please do share!

Early Conclusions

To my surprise, the Ceylonese seeds began sprouting within two weeks. This was totally unexpected, as the Thai seeds did not arrive for 5-6 weeks.

However... the Thai seeds were kept at 100 degrees. The Ceylon seeds were kept at 90 degrees. Did it make any difference? I haven't a clue.

The germination rate for the Ceylon seeds is 25% - so far. I'll wait another few weeks before having a firm number.

Plant Whisperer® to the Rescue!

I mentioned my Kaffir Lime seedlings to a friend a few months ago. As it happened, he knew of a man who has developed the world's first Light Emitting Computer - a device he called "The Plant Whisperer®. Rather than try and explain this magical device, I've linked to the developer's website so you can read about it yourself. (I have no fiduciary interest in the company.)

I was delighted when the developer offered to lend me a Mark V Plant Whisperer® for a few months, programmed specifically for my Kaffir Limes, After two weeks exposure to the device, the seedlings are showing signs of explosive growth.

Here are a few snippets from the Operations Manual:

The Mark V controller allows construction of 10 custom 'spectrum' settings which are stored in permanent memory. (There is also a setting which turns the light off.)

Spectrum settings are picked up to eight times a day by a program which is set to a 24 hour cycle. The controller can store 8 programs.

When you set a program to run, it acts as a timer which switches the lights up to eight times a day. The program calls upon a spectrum setting when switching the light at those times-of-day entered into the program when created.

One example might be a period of darkness, ending with a dawning light, which then becomes that portentious power of morning, eventually intensifying to mid-day sun; gradually softening toward an evening light and then on into twilight, finally ending in darkness once again.

I am taking photographs every twelve hours, so that the developer can create a 90-day time-lapse sequence. These photos are already documenting amazing progress. When the time-lapse sequence is available, I will link to it here. In the meantime, I'll share a few photos with you...

Take particular note of the plant on the far left, and watch the change in the new leaf at the top...you can see the difference in just 36 hours.

The Camera

The camera is my aging Canon T1i mounted on a Manfrotto 290 Series Tripod with a white defuser on the flash unit.
The camera is my aging Canon T1i mounted on a Manfrotto 290 Series Tripod with a white defuser on the flash unit.

A Changing Spectrum World

This photo gives you a good idea of the setup I'm using to photograph the plants - and a good look at the Plant Whisperer® Mark V. The cables leading down from the MkV connect both the power supply and the computer which controls the spectrum changes and their schedule.

The lights are currently on for 18 hours a day and move through six spectrum changes from red, blue and green to far red, and then go dark.

The wavelengths (measured in nanometers: 'nm') emitted by the LED used in the Mark V lighting heads are Royal Blue (430nm), Bright Blue (450nm), Emerald Green (530nm), Amber (600nm), Blood Red (668nm), and Far Red (730nm).

Two leading horticultural experts explain the importance of this process:

"Light is a potent regulator of plant growth and development, impacting gene expression to global physiology and metabolism. Plants sense a broad range of wavelengths, from UV to far-red, through separate photoreceptors. These light sensors direct adaptive responses under changing environmental conditions and specifically activate precise downstream signaling pathways.

"Research studies in photobiology ... have characterized light effects on many plant behaviors, along with the genetic mechanisms that control them. Transferring this knowledge to crops has opened a new field in plant science where variation in light quantity, quality, duration or combinations can be used to change plant growth, development or metabolism to influence a desired final product." (Sofia D. Carvalho & Kevin M. Folta, "Environmentally Modified Organisms – Expanding Genetic Potential with Light," Critical Reviews in Plant Sciences, 33:486–508, 2014)

Plant Whisperer - Early Results

October 11th, 9PM
October 11th, 9PM | Source
October 15th, 9PM
October 15th, 9PM | Source
October 21, 9AM
October 21, 9AM | Source

Upside

Since putting the Plant Whisperer MkV to work, I am continually astounded at the unbelievable growth shown.

It is clear to me that the slow, almost non-existent growth I'd seen in the past two years was a direct result of our Zone Five light. Being able to program a device to provide the same light spectrum these plants would enjoy in the Far East has been an awesome eye opener.

Although I have no interest in having more than one or two Kaffir Limes around the house, I'm giving serious thought to buying more seeds to see how they would fare being germinated under the MkV. If I decide to do that, I'll start fresh on another page. Stay tuned.

Downside

These plants grew so rapidly (See video, below) that I began to feed them out of fear they were consuming their nutrients too quickly; the rapid growth had already resulted in roots extended outside the containers.

The seedlings were transplanted into much larger (1-gallon) pots on October 23, 2015.

The larger pots were filled with 50% Sea Soil® (bottom) and 50% organic top soil.

This mandated moving plants and The Plant Whisperer® to a new, larger location.

May we live in interesting times.

The First Fifteen Days

Kaffir Limes Transplanted

By October 23, 2015, the plants had outgrown their small pots, and had to be moved into the one gallon pots I mentioned earlier.

I purchased an Oatey Plastic Drip Pan (see above & below) to protect the new floor in my office, moved The Plants, Plant Whisperer® and camera, and the plants and I are good to go for another few months!

That brings this page to an end...the Kaffir Lime saga will continue here,

I don't expect to see any growth for the next week as the plants adapt to having been disturbed. Until then, keep well!

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Onward & Upward!

Transplanting the growing plants required a completely new setup.
Transplanting the growing plants required a completely new setup. | Source

This is the tray I bought to contain moisture.

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