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  Limestone Substrates
From: Theodore Held <oppenhauser2001 at gmail.com> on 2010.10.19 at 15:19:00(21571)
Ted Held.
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From: Jay Vannini <heloderma5 at hotmail.com> on 2010.10.20 at 18:38:58(21574)

Don't want to bore you with gory detail, but "yes", I have done a lot of experimentation with growing both Malesian and Neotropical aroids at media having different pH (native and amended) and, "yes" some otherwise tricky aroid spp. respond well to this fine tuning of the root-soil interface in captivity. "No", not all putative calciphiles require alkaline substrates to thrive and many prove to be quite adaptable to a wide range of pH and physical media structures.

Note: many (but by no means all) plants originating from karst formations or regions with underlying limestone substrates are actually near- or functional calciphobes. It very much depends whether or not the plant is actually rooted into the underlying rock or grows in the (acid) decomposing leaf litter layer that covers it. You really need to know a bit about the plants' ecology prior to just assuming that since something is associated with karst formations it necessarily needs a substrate of >ph 7.5 to thrive. While not as evident in aroids, this phenomenon is well known to growers of tropical butterworts (Pinguicula spp. Lentibulariaceae) and understory palms.

I would also take up your point about chemistry: that there are some not insignificant nutritional/toxicity considerations to take into account when one couples very acid or very alkaline substrates and prima donna plants.



> Date: Tue, 19 Oct 2010 11:19:00 -0400
> From: oppenhauser2001@gmail.com



From: Brian Williams <pugturd at windstream.net> on 2010.10.21 at 00:54:34(21575)
This is very interesting. I have been for the last few years put out
a sign for fall leaves here at our nursery. People bring tons of leaves
every year and I use them to mulch up plants and to make a huge compost
pile for soil to use in future beds. This year I had to bring in a
number of tender plants into our heated greenhouses. Running low on soil
and knowing that the plants would be thrown back in the ground come
spring I decided to use a leaf compost mix as I have in years past.
These leaves are usually only 1 to 2 years old and are half way to
pretty much composted. In years past I found that the plants sitting in
these pots of leaves would not produce any new roots and that in most
cases would rot. Which has been upsetting to say the least. I have been
wondering why and blaming most of it on the cold roots. This year I
added 2 bags of lime dust to the mix as well as small Styrofoam
pellets. The Styrofoam pellets were found at a local styrofoam
recycling center that has a certain type of sytrofoam they cannot
recycle which are slightly heaver than normal. These styrofaom pellets
are then throw away or are sent to be used in bean bags apparently they
have no other use and the recycling center was happy for me to take a
ton off of their hands. I found this helps keep my soil very airy and
drainage much better and plus they are free and in a sense are being
used once again in my beds.
I have never thought about really using this soil mix as a potting mix
for my collection or prized plants sense I have had multiple problems
with it in the past. It has always been used as a very cheep
alternative for storing my summer collection for another season. But
this year after moving a few plants into this mix and placing them into
the greenhouse I have noticed roots already growing out the bottoms of
the pots in just a few days time. It makes me wonder with many of these
aroids such as Amorphophallus Alocasias and others that grow naturally
in small limes stone pockets in leaf litter are getting a taste of home
in this mix. I plan to test this further, I still have a lot of
questions myself especially over how weedy is this mix and how the soil
will act once it really decays in the pots.
Still adding the lime dust and styrofoam has made me look at this mix
completely different and as having much more potential than I had
expected. Plus the total cost for pile 6 feet tall was 6.00 due to the
fact I bought the lime in small bags rather than bulk and used the
bobcat to mix it up. I will try to write down some ratios as I test the
mix further to see what works best. I am a bit worried as it seems a bit
to easy for it to work this well.
From: "Derek Burch" <derek at horticulturist.com> on 2010.10.22 at 17:08:32(21577)
Hi Jay (and Ted and Brian),

The observation on pockets of decomposed
litter in the limestone is exactly what we observe for some of the ferns here
in South Florida. And I think that Peter Boyce
has commented on these growing sites in some of his recent papers.

So, Jay, this wouldn’t be in the least
boring as an article for Aroideana … When can I hope to see the manuscript? (That
will teach you to keep your head below the parapet, although I was coming after
you anyway, soon).

Regards, Derek



From: Theodore Held <oppenhauser2001 at gmail.com> on 2010.10.22 at 17:30:12(21578)
Ah, good. I was afraid that I was off here in the ozone all by myself.

There are definitely chemical issues here, as well as ones of
extremely localized "pockets" of organic debris that may be insulated
from surrounding karst (a type of calcium carbonate rock). In acidic
environments, iron is more readily available. But so is soluble
aluminum, which can be a toxin at those pHs. On the alkaline side,
other nutrients become more available, while iron becomes limiting.
The subject is complex to say the least.

My interest lies in presenting a possible alternative for plants that
are reluctant to grow despite seemingly perfect aroid growing
practices. I have plants like this. On one level I have plants that I
just have no luck with. Others grow fine, but will not flower despite
my best efforts. I was hoping that something as simple as the addition
of agricultural lime or dolomite (a calcium and magnesium carbonate
double salt) would work. It looks like it's worth a try. Certainly
agricultural liming has been proven successful for certain soils for a
thousand years. Why not for aroids?

Ted Held.

From: brian lee <lbmkjm at yahoo.com> on 2010.10.22 at 17:34:26(21579)
Dear Ted, Jay, Eduardo, and All,


I second all that Jay has said. Jay, your articles in the latest Aroidiana were excellent. Keep writing articles about aroids in habitat and associated flora. I really enjoyed reading about the association of Zamia in the wild with Araceae.

Ted, I am often experimenting with pH on plants that seem to want something other than what I am supplying them. It would be nice to have ecological habitat data on all the plants I grow. However, there are many unidentified taxa in cultivation that have poor or no locality data or incorrect data. This is highly unfortunate as one must start guessing on preferable pH, if the plants are not thriving. A plant that is in declining vigor may be in that state for all sorts of
variables; pH being only one factor. Elevational data is another important factor. If locality data is not recorded and associated with an undescribed species; botanists would be reluctant to describe them. If the habitat is then destroyed and the original locations cannot be determined, this is very tragic for taxonomy and other reasons. When one starts to cultivate a new plant, it is always helpful to have habitat and ecological information to begin a horticultural protocol. One can be lucky and have a taxon that is very adaptable, but, if a plant is an obligate calciphile, the pH must be adjusted or the plant will languish.

Eduardo, I must also praise you for writing about the Araceae of Brazil in these limestone outcrops. It was a great article on a poorly known habitat. I may throw some lime on a few of my Philodendron subgenus, Meconostigma, to see how they



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