Monday, February 4, 2013

Amorphophallus konjac - Corpse Flower

I have a confession to make.  Since my last post in fall, I've been feeling planted out.  I didn't want to think about plants, and that's no way for a plant geek to feel.  Hence, no posts.  I'm starting to feel back to normal now, which leads to a 2nd confession.  I've been thinking about plant sex a lot lately.  (And apparently so has Joseph at Arrowhead Alpines)  Most recently about Heuchera breeding (more on that in the future), but it started thanks to a recent event:  My Amorphophallus konjac are sending up flower stalks! 

Amorphophallus konjac is the hardiest in this aroid genus.  I bought my first one in 2004 from Plant Delights Nursery, and since then they have grown and multiplied quite readily enough that we sell them and it doesn't look like we're in any danger of ever running out of them.  It's a prolific species when it comes to offsetting.  But they've never flowered, despite the description of "3-4 years from flowering size."  It's taken 9 years for that first one, and only 6 years for the first offset I got from it.  Apparently I didn't treat the first one well enough in the first couple years of life, which slowed it down. 

In any case, A. konjac is really easy to grow and the best candidate if you're new to growing Amorphophallus or aroids in general.  Despite being zone 5 hardy, I do grow mine as potted plants.  I pot them up every year in May or June depending on how our crazy spring is going.  They like it warm, and generally don't emerge until late June.  I've learned to use a bigger pot than necessary, as I've had the growing corms break plastic pots.  I use a well drained soil-less mix and a slow release fertilizer like Osmocote and plant them about 2-3" deep.  I keep them slightly moist, making sure I don't let them dry out completely. 

I keep them in the sun for warmth until they sprout, at which point I move them to partial shade.  Keeping them in morning sun or late evening sun is fine, just avoid sun during the hottest part of the day.  Once they sprout and are actively growing, I will also use a water soluble fertilizer like Miracle-Gro Pro once every 2 weeks.  This regimen has lead to fast growth and significant annual increase of the corm size. 

Once the plants go dormant in fall I first remove the foliage.  Then I remove the corm from the pot and clean off all of the soil, watching for offsets.  They're usually pea sized or a little bigger.  Of all of the plants I store in winter, these are the easiest.  Just set the bare corm on a shelf somewhere cool.  Usually I put mine in the basement, just don't forget about them in spring!  You can use the same method if you plant them in the garden and dig them up in fall.

If you want to try planting them in the garden, a couple things are important.  Well-drained soils are a must.  It isn't usually the cold in zone 5 that kills them, but the moisture.  If it's too wet in winter/spring, they will rot.  As Amorphophallus konjac grows, a well forms around the shoot on the corm.  To prevent this from collecting water in the garden, plant the corm on its side.  The shoot will find its way to the surface without a problem.  Also, plant them fairly deep.  Corms can get very large, mine are bigger than a softball right now and they can get bigger than a basketball!  I will be planting out some offsets this year, and will be placing them 6-8" deep.  Also, winter mulch once the soil is frozen will keep the soil from thawing and re-freezing too quickly once spring arrives. 

If you've never encountered Amorphophallus konjac, they're a really cool aroid.  They're related to Jack-in-the-Pulpit (Arisaema sp.)and Peace Lily.  The corm sends up a single palmate leaf on a mottled stalk.  Flowering is an event I've looked forward to with excitement and dread. They typically bloom in spring, then the flower fades and the plant rests until late June when it sends up a leaf.  Even in storage in the cool temps of my basement (55-60 degrees), mine have sent up their flower stalks.  I was hoping they'd wait until the outdoor temps (it's 21 degrees today... kind of warm) were a little more moderate and I could keep them in the garage or the screen porch.  They get their common name from the aroma of the flowers.  They're pollinated by flies.  The best way to attract flies?  Smell like a rotting corpse.  The same thing happened with my Sauromatum venosum -check it out here.







13 comments:

  1. You are absolutely right: Amorphophallus Konjac is easy to cultivate and the right choice if you're fresh to growing plants of the arum family. Thank you for the informative post.

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  2. Hi, My grandmothers Amorphophlus is about to bloom. I was woundering how long do they flower for?
    Thank you.

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  3. It depends on which species, some might only be 2 days; my A. konjac bloomed for about 5 days. Make sure to take pictures! And be prepared for some smell. :)

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  4. Hı, do you know when to seperate Thé child bulbs from main corm ?spring ?winter ?

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    1. I usually remove offsets in fall when I clean the plants for winter storage. If you live somewhere this is hardy and grows in a garden year round, any time it is dormant should be good.

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  5. I live in Michigan and have had one of these "voodoo lilys" for almost 4 years, every spring i plant the bulb in our garden, absolutely beautiful huge leaves and plant! Definitely one of our favorites and most discussed! Every fall (before the first frost of course) I cut down the leaves and stem and place it in a paper bag in the basement… Last week while starting my spring cleaning the huge human head sized bulb had this enormous stalk and bud standing almost 4' tall! It scared the sh*t out of me! Do you suggest I bring it upstairs to warmer climate and actually sun light?? I just left it there because I was obviously SO excited and scared I would ruin it! Help!!!!!! I want to see this thing flower!!!!

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    1. Absolutely, bring it upstairs in the light so you can see the flower and let it color up properly. Be prepared for the smell though!

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  6. Hi I am a newbie at growing A konjac. My bulb is growing beautifully, should I take it out of the soil every fall or can I grow it indoors?

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    1. I have not tried to grow it indoors as a houseplant. It is worth a try, I expect they'd need around 12 hrs of light and steady warm temps above 70 degrees. I just remove mine from the soil for winter and pot it up when we have warm weather.

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  7. Hi I am a newbie at growing A konjac. My bulb is growing beautifully, should I take it out of the soil every fall or can I grow it indoors?

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  8. I've had my Konjac plant for about 3 years and I'm SO excited as it looks like it's going to flower for the first time. The corm is about 6/7 inches across and has a thick spike of 5 inches or so, which it hasn't done before. I have kept a couple of dozen 'babies' from previous years. I have kept them in our spare bedroom where it's cool, but it's still not potted up yet as I've previously done it around May. Don't know how we'll cope with the smell as don't think it will be warm enough to put it outside for a couple of months yet. We're in south-east UK.

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    1. I used a plastic bag to enclose the flower after taking several pictures. That kept the smell to a minimum. I would think this is hardy enough for the garden in the UK, isn't it? It survives to about -28C. Controlling moisture during dormancy is probably the biggest issue, really well-drained soil and planting corms on their side can help. It might be worth planting some of your babies out in the garden and seeing how they do.

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  9. Here in zone 4, I am about to enjoy a second bloom of my Konjac. I didn't think that the plant was suppose to bloom annually, but it is. The flower stem is about 18" taller than last year. The plant should be in bloom this coming week.

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