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Amorphophallus (and Other Tuberous Aroids) Care Guide

David

Founder
Staff member
#1
General Introduction
As with any number of subjects, it's quite easy to get lost in the plethora of information available and become discouraged at what may seem like a daunting task at the beginning stages of mastery. The content here is written primarily from personal experience, sprinkled with additional observations embedded by other growers over the years, and serves as a foundation in which you can have fairly good understanding of how these plants grow and the kind of care necessary. While this guide serves as a simple introduction to this special group of plants, do not be alarmed if things don't work for you as you may initially expect; lighting conditions, temperature, watering schedules, and other factors specific to your location and habits may require a bit of tinkering to get right. Thankfully plants are also incredibly forgiving and, aside from extreme cases, can be brought back into a healthy state with a little effort and time.

One thing to keep in mind is that plants are like animals: Living things that are affected by factors around them and though they cannot speak, they do have their own methods of communication if one knows how to read the signs. Reading plants is a skill that takes time to develop but as you continue to work with them, the easier they are to understand and predict. At the end of the day all gardeners, from newbies to gurus, are always learning, experimenting, and adapting.

This guide will be fleshed out over time with additional information whenever possible. Please do not hesitate to ask additional questions or ask for a section to be added/expanded if you feel it may be helpful. With that out of the way, onto the fun part(s)!

What species does this apply to?
While I write this with mainly Amorphophallus species in mind I've also applied the same approach to Gonatopus boivinii and Synandrospadix vermitoxicus. I'm currently observing how well these same methods work with a few Anchomanes, Gorgonidium, Pycnospatha, and Dracontium species. There are exceptions to growing certain species—some can seem quite fickle at times—but for the most part you should have little trouble adopting this guide for your needs.

Which of these are easiest for beginners?
The plants I feel are easiest to start with specifically are Amorphophallus bulbifer, A. konjac, A. impressus, A. paeoniifolius, and Gonatopus boivinii, though there are a few others that can fall under that umbrella as well. These specific plants are generally hardier than others, easier to find, inexpensive (particularly if you are not successful for whatever reason the first time around and want to try again), and can handle some neglect without serious adverse reactions. Once you are comfortable growing one or a few of these, moving on to other species isn't that difficult.

Soil and Fertilizer
Just as the food you eat affects your health and mood, the same goes for plants and what they absorb through their roots has an affect on their growth and development. Another important component is balancing the ability to retain water while allowing proper drainage, and also avoid soil compaction (roots need to breathe too). When you consider that at a plant will be spending, at minimum, a year in the same pot, this is an important foundation to get right from the beginning.

Although this all sounds complicated, what this really refers to is the right combination of materials used to make up the soil that meet these requirements. Most soil mixes can consist of a combination of the following:
  • Sphagnum peat moss
  • perlite
  • charcoal
  • vermiculite
  • composted plant material (using old leaves is perfect for this)
  • pumice
  • sand
My base mixes start with Vigoro All-Purpose Potting Mix, which for the most part is a good start with a touch of fertilizer already added in, at which point I'll supplement it with some of the above to get a good mixture. The end result is something "light and fluffy" that will allow the plant roots to breathe, retain moisture, and allow drainage of additional water.

For fertilization purposes, I use a general slow-release fertilizer (Osmocote is one I have used before), with an additional helping of bone meal on top of that (Jobe's Organics Bone Meal has been noted by some growers to be a good choice). This is all thoroughly mixed into my soil and once finished, the soil is ready to be added into pots along with the plant.

Size Matters (For Pots)
The second most important element in growing these plants is the container that they grow in. There's two things to keep in mind regarding this: The size of the tuber/corm and leaving room for the roots to grow. When the plant first awakens from dormancy it will send out anchor roots that will quickly travel away from the growth point in all directions. The tuber itself will then begin to shrink as it is absorbed during the development of the leaf, and over the course of the year will be replaced by a new, larger tuber in its place. It is essential to leave room for both of these things to happen; you don't want to have too little room for the roots to grow and strangle themselves (rootbound) and at the same time there needs to be space for the new tuber to become larger (I have had plants break open pots if it was not large enough too). An easy way to figure out proper plant size is to measure the tuber and getting a pot that is two to three times the diameter of the plant (e.g., a four-inch tuber should be potted in an eight-inch pot).

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This Amorphophallus ferruginosus demonstrates the difference between pot sizes. The pot on the left is barely enough room for the tuber itself, and when the roots grow
that space will be quickly used up followed closely by the new tuber. The picture on the right shows enough room for both tuber and root growth to occur comfortably.

This rule of thumb can be used with confidence for most species, but there are some where it may be necessary to place them in a pot three to four times the size, as is the case with Amorphophallus konjac and A. impressus. The reason for this is that these species (as well as a few others) produce stolons that—rather than growing alongside the mother plant like other species—elongate out and away by several inches in random directions. You may still find the offsets pushing up against the sides of the pot at the end of the season, but the larger pot will allow just a tad more room for them to expand before meeting the edge of their container.

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An Amorphophallus konjac with multiple offsets growing from the main tuber.

Winter is Over, Time to Grow!
Naturally a common issue is knowing exactly when the right time is to pot them up. This is likely the easiest thing to look out for. Usually I wait until the new root buds appear just above the origin point for the plant.

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New root buds form between the tuber and the new growth as shown on this Amorphophallus ferruginosus and Sauromatum venosum respectively.

Once the plant is ready to move into a pot, the next step is to ensure the it is buried at an appropriate depth. The tuber should be placed with the growth point at about mid-height of the pot and in the center if looking down from above.

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The green arrow indicates the main growth point for the
tuber and should be placed in the area indicated by the green line.


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This Amophophallus borneensis is now in the appropriate depth and is the pot can now be filled up the rest of the way with soil.
 
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