Colocasia gigantea “Thailand Giant”

The first year (2012)
The second year (2103) with weekly fertilizer

It was love at first sight when I first saw this plant. Living in Indiana, I love to have that tropical feel in my backyard during the summer. I bought this plant online and planted it in a pot after the threat of frost was past. It was a beautiful addition to my patio.

Keep in mind that in its native habitat, it reaches heights of 9 feet or more. My plant, however, only reached a height of maybe 3 feet.  The leaves were truly gorgeous though. You can see plant in the above picture, which is directly behind the standing woman (me!).  I’m confident that with a longer growing season plus more fertilizer would have made this plant grow exponentially more than it did. I will be experimenting with that next summer.

With its native habitat being Thailand, it prefers zones 8-11. This is important information when considering your overwintering needs. After some research, I learned that not all species of the Colocasia genus are quick to grow corms. And this happens to be one of those. For my growing zone, this particular plant should be brought indoors during the winter and placed in a cool location (45-60°F) with bright light, being careful not to overwater as this plant will be semi-dormant. I have chosen to overwinter this plant in my garage under a grow light.

Harvesting the Seed
As Autumn approached, the plant produced several inflorescences, I wanted to try my hand at propagating it. Inflorescences are essentially the complete flower head, shown in the picture below, consisting of the spathe and the spadix.  The spathe is the white thin bract that surrounds and protects the spadix.  While the spadix is the spiked center portion, which contains the male and female portion.
Pollination occurs when the male portion of the spadix produces a powdery-like build-up of pollen. In nature, the pollen can be transported with the help of insects. Hand pollination can be achieved too, especially if your plant is contained indoors.
Individual seed pods are located towards the bottom of the spadix, which is the female portion (see picture).   Each seed pod will be about the size of a pea when ready for harvest and the individual pods are full of seed. An entire seed head may have up to 100 or so individual seed pods. So, there is a potential for thousands of seeds!

Seeds shown settling to the bottom of the bag

When is the seed ready?
You will want to wait until the white portion of spathe actually falls from the plant. The seed will develop in the lower (female) portion of the flower. After 3-4 weeks, cut the flower completely off at the base of the female portion. You can then peel that surrounding green portion that is around the female part and you should see the swollen seed pods containing seed.  Take the entire seed pod, soak it in a Ziploc-style baggy with 1/3 water and all the air pressed out. Let the seed pod soak for a couple of hours to soften. Once soft, massage the entire seed head and you should be able to see the tiny seed. Try to get the seed to sink to the bottom of the bag (see image below).












An Alternate Method
Now I’ve also read where if the spadix is left alone, the female portion of the spadix will eventually rupture open full of seed.  From there, the seeds can be extracted.  I have yet to try this technique.  However, I have successfully extracted seeds with the prior technique.  I then dried the seeds and will propagate in the Spring.

Anyone have any thoughts or experience to share?  Please feel free to share your knowledge.

6 thoughts on “Colocasia gigantea “Thailand Giant””

  1. I also have several of theses beautiful elephant ears, I am trying to harvest the seeds with no luck. From what I read I needed to wait until the pod busted open, Ive been waiting and now the pod is dying, I cut it off and opened it up and the pod is black. I read what you wrote and Im thinking about trying it. I wanted to make sure I understood what you were saying, do you wait 3-4 weeks after the flower falls off before you cut the seed pod off?

  2. Hi Carmen- That was how I was instructed by an individual who is knowledgeable and successful with the process. Wait until the white portion of the spathe falls off. Wait 3-4 weeks. You should notice that the female portion should be swollen. I must tell you, that I did not have any of the seeds that I harvested successfully germinate this year.

    I can also tell you that my pod never busted. I harvested before the pod busted. If I were you, I would try to harvest anyway and see what you get.

    I did, however, have several baby volunteer plants that were growing in the pot this spring. So, some success was had!

    I will try again this year and I will update this post.

    I’d love to hear from you on your success.


  3. It’s getting cold and the flowers have fell off the pods several weeks ago. I pealed back one and there was a brown mucas surrounding the seed pod! Is that normal?

    Another question: I heard or read something about the seeds won’t be good if they are not pollinated. How would I know if they are?

    We are trying something new this year we have build a small greenhouse over one of our giants with heat, water and fan.. (the one with the huge pods) i want to see how big it will get and wanted to protect the seeds…. Crazy I know right?

  4. Hi Carmen-

    I didn’t have any brown mucus that I recall so I can’t tell you if it’s normal.

    Last year, I did not self-pollinate my seeds but was instructed there is more likelihood of seeds developing if you self-pollinate with a brush. Since I didn’t self-pollinate, that explains why none of the harvested seeds propagated.

    My big guy is overwintering under a grow lamp in the garage.

    I’d love to hear how yours do in the greenhouse. And I don’t think it’s crazy at all. I find I need those wintertime activities to get me through the season.

    Good luck!

  5. I love these plants. Over a decade ago I purchased one and after a couple of years I decided to harvest the seed and try growing them. I live in the DC area. I had no luck overwintering the corms in the garage. By Mid-February I had a pot of mush.

    In August the plants begin to bloom. I watch the beautiful flowers for the male part of the plant to produce pollen. There will be lots of it. Gently I squeeze the female part of the flower to get as much pollen into the waiting ovaries. Do this on several flowers so I am guaranteed some success.

    Then I wait….This year I waited until the night they were calling for the first frost and went out and harvested the largest fruit. I put the fruit in the garage and waited another two or three weeks before harvesting the seed. The seed has to be planted when fresh. As the seed drys out it loses viability. On November 20th I harvested the seed by opening the best looking pods and squeeze the pea sized fruit to release the seeds into a cup filled with water. Yes, there is a slimy mucus but that doesn’t both me. After I have a couple of thousand seeds in the bottom of the plastic cup I use a spoon to clean up the stuff floating on the top and then pour the mix through a paper towel to have a nice pile of seed.

    I sew these immediately on ProMix potting mix trying to not put the seed in too thickly. Using cell packs I put 3-10 seeds per cell and put a plastic dome over the seed trays. Then they are put under lights. 23 days later I start to see little green plants. In the two trays there was probably 1,000 plants.

    After growing for another 4-5 weeks they were large enough to handle and move to individual cell packs. Smallest plants were just trashed.

    Now I have 4 trays of 36 plants each under lights. I don’t want them to get too large under lights since they take up space and the leaves tend to get tangled. My last frost date in April 20th. From the 144 plants I have now I will cull out the smaller ones and keep the largest 60 or so which will be potted up to 3 1/2 pots then 6 inch pots before planting outdoors.

    Last year my largest of the 20+ plants I had in the landscape was about 7 feet tall and the kids in the neighborhood love them. I’ve given them to friends who now love them and there is a friendly competition between us. Even non-gardeners are impressed by them. I have lots of Elephant Ear stories over the years.

  6. How cool, Gene! Thank you for that information. I would love to see pictures of your plants. If you have any pictures, maybe you could post them on my Facebook page?

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