Dead Horse Arum

Leo A. Martin
Thu, 19 May 2011 16:52:45 PDT
I've had two Helicodicerous for several years, one kindly provided by
James and one from a nice person on another plant list.

They sprout when we get over a week of warm weather here in Phoenix
(usually somewhere between February and April) and die down after the
first week or so of weather in the 90s F or above (mid to upper 30s C),
even if nights are still cool. This year they were up in Feb and are dying
down now. Haven't had blooms yet but they grew very well this season. I
have them in 8" / 20cm wide and deep plastic pots. I have noticed the more
I fertilize the better they grow. I may have two different clones; they
look a little different in leaf and both sprout and die down at slightly
different times, so I hope they flower together some year.

I have tried moving the pots under cover for the summer to keep them dry
and also leaving them out to get our scant summer rain. I can't tell
whether this matters. I put the pots out in the open when nights begin
cooling in late October and start watering. I keep the soil moist all
winter if it hasn't rained but they don't sprout until after the coldest
weather is gone.

I have been told they need more winter cooling than Phoenix gets and that
I should dig them in the fall, put them moist in the refrigerator for a
few weeks, and plant out again when they sprout roots. I wish I had time
to try this. The past few winters we have had a lot of cold (by our
standards) with sporadic freezes to the low 20s F / -5C. I left them
outside and they have done well.

Helicodicerous are susceptible to spider mites here but not much as
Sauromatum and Amorphophallus konjac, which two I can't keep alive here
for that reason. Interestingly Amorph. paeoniifolius is not a problem here
at all though I don't have one at the moment. But for some reason no
spider mites on the Helicos this season at all. Maybe the cold?

For those of you who grow Helicodicerous well: What are your temperatures
like when it sprouts and again when it dies down? At what stage of growth
does it flower? Are 8" pots suitable for flowering, or should I go bigger?
If I ever do luck out and get two plants flowering, how should I pollinate


Leo Martin
Phoenix Arizona USA

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