Amorphophallus is a genus of the aroid family just like Alocasia, Colocasia and even the well known calla lily.
If you are not too familiar with the genus of these "phallic" plants, you may still have heard of "Mr. Stinky" that grows in the greenhouses of Fairchild Tropical Gardens in Miami, Florida.  That is nothing less than Amorphophallus titanum, a giant aroid that produces an inflorescence after about 8 years if grown from seed.  But beware, the flower smells worse than a thousand dead rats together ever could.

General characteristics of Amorphophallus

The flower of these plants really looks like the typical aroid.  There is hardly any mistaking possible, although plants like Typhonium could be taken for Amorphophallus too if you are not too familiar with this kind of plants.
The flower is one of the most renowned features of Amorphophallus.  The flowers are beautiful, not to say divine, but sadly enough, God has not doted them with a divine perfume...  From the smallest species to the biggest, their smell is absolutely wretched. 

All Amorphophallus grow the same way.  They all have a tuber in the ground that produces one single umbrellalike leaf.  According to the species, this leaf is gigantic or rather small.  The tubers go dormant after the growing season is over.  In spring, a new leaf will emerge.  When the plant has reached flowering size, it will send out a flower bud in spring, instead of a leaf.  The flowers don't last too long, so make sure you are there to enjoy them, but don't forget a gas mask!!! If the flower has had good sex, it will produce berries on the remains of the inflorescence.  The seeds will ripen in there.  We'll get back to the seeds later, as there are some very important sings to be said about them.  After flowering, the bulb may go dormant again, sometimes even for more than a year, so don't panic!

The shape of the tubers themselves vary greatly among the different species.  Some, like the Amorphophallus titanum, produce giant bulbs/balls, but other species have corms shaped differently.  Amorphophallus longituberosus, for instance, looks more or less like a carrot.

The seeds

Seeds of Amorphopallus are quite small, even of the biggest species.  They are even smaller than peas. There is a famous exception to that: Amorphophallus titanum.  This giant also has giant seeds that can measure up to almost 2 inches long and more than half an inch wide.

It is important to know that Amorphophallus seeds are very tender and extremely vulnerable.  The seeds do not have a hard seed coat that can protect them from drying out, so keep them moist at all times.  A dry seed is a dead seed.  Therefore, the safest way to store seeds is to keep them in the fruit itself.  Moist sphagnum is a great alternative.

Germination of Amorphophallus is extremely easy.  Most species will even germinate already while being stored in moist sphagnum (if all the fruit pulp has been removed).  A couple of weeks after sowing, you should have lots of seeds germinated already.  A germination rate of nearly 100% is not rare at all.  There are some species, like A. kiusianus, however, that do take more time for germination.  But even then, it is nothing compared to the germination of some palm trees who can take up to two years.

Culture

We can only give some general tips here.  It all differs according to the species you are growing.  Some are quite hardy, others are plain tropical.
The hardiest species like A. bulbifer, A. konjac, A. kiusianus, A. paeoniifolius, etc. are really not too hard to grow.  There are two things that might be a problem: a summer that is too short for the plant to really develop well and rot.
The last problem is very common for Amorphophallus.  Sometimes, a bulb (even an old one) can decay for no reason at all it seems.  So be careful and check your bulbs regularly, especially when dormant.

Of course, it is evident that tropical species will not take frost too well at all.  There are reports of A. titanum surviving some light frost for a couple of hours in South Florida, but even then, the corm still might be severely damaged, so don't take the risk.  Species like A. kiusianus and A. konjac have proven to be hardy even in zone 8, so do try when you have some spare bulbs.

Tropical species always require high temperatures and high humidity.  Species like Amorphophallus titanum and hewittii illustrate that very well.  That doesn't mean that the temps always have to be in the eighties, but 40-45F for too long may really harm the plant. 
These plants also require a lot of water.  The bulbs rot easily, so you have to make sure that the soil is drained well, but never let it dry out too much, especially during growing season.  During dormancy, keep the soil slightly moist to avoid both rotting and drying out.

The more hardy species like A. bulbifer, konjac and kiusianus can take lower temperatures quite well.  Especially the kiusianus likes cool weather.  Temperatures above 80 make the leaf die back fast.  Bulbifer and konjac can take both hot and cool weather in summer.  If you are in zone 7 you can still consider planting them with some minor winter protection (eg. a layer of mulch). 
Dormant konjac bulbs rot easily.  The safest is to have them stored dry.  I have experienced with bulbifer however that they dry out easily, especially when the bulbs are still quite small and that it is best to keep them in moist soil during dormancy.  The same counts for the young bulbils that grow on top of bulbifer leaves.  They dry out easily and do not recover from that.

Propagation

Propagation usually happens through offsets.  Some species like Amorphophallus konjac produce small tubers like crazy.  That also gives you the opportunity to experiment freely without risking too much money.

Another way to reproduce these plants are leaf bulbils.  Some species, like A. muelleri and A. bulbifer, produce small bulbs on the leaves themselves.  After the growing season, the leaves will die back and the bulbs can be harvested.  They will make a new plant next spring.

Sowing is, like for any other flowering plant, one of the options.  Do take into consideration what we have said about the seeds before, and I'm sure you will be successful.

A last option that we don't want to keep from you is leaf cuttings.  I have heard of different ways to do this and there doesn't seem to be a big difference in the results, so you can just pick what you want.  You can either use the leaves themselves to make cuttings or you can use the petiole.  When you have taken the cuttings, plant them in a moist medium (eg. potting soil with perlite) and build a mini greenhouse around it, so that humidity stays very high at all times.  This will not always work, but if it does, the part of the cutting above the ground will finally die, and under the ground, you will have a small bulb that will start to grow next spring.

Beginners

For the beginners, there are a couple of species that can be found easily and for little money.  One of the easiest Amorphophallus is A. bulbifer.  It has even proven to be quite hardy in cooler climates and it produces new bulbs very easily.  A. konjac is another one that you can find easily.  It is a big one, quite hardy and quite cheap.  It produces offsets like crazy, so you will have plenty of plants to experiment with.  This species will make your visitors very jealous when they see the big leaf or the flower.  However, your visitors may not be able to handle the stench of this gorgeous burgundy flower...

More information

For more information, you can always visit the very useful website of the IAS (International Aroid Society): www.aroid.org, more specifically: http://www.aroid.org/genera/amorphophallus/amorph.html
You will find a lot of information and pictures of more than a 100 of the 172 species of Amorphophallus there are.

Of  course, everything you read online is just a beginning.  You will have to experiment a bit yourself and in time, you will become a master at growing Amorphophallus!

Happy growing!!

If you have any suggestions or comments about this, please let us know at rareplantsflorida@yahoo.com