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From: aroid-l-bounces@www.gizmoworks.com
[mailto:aroid-l-bounces@www.gizmoworks.com] On Behalf Of Hannon
Sent: Wednesday, December 14, 2011 11:15 PM
To: Discussion of aroids
Subject: Re: [Aroid-l] Cultivation of Taccarum
Hi Christopher,
That is a good point. The "average humidity" for nearby Pomona is 43%, which
in reality means daytime humidity mostly <43% and nighttime humidity over
43%, often reaching the dew point. The Los Angeles area is a semi-arid zone
with a strong coastal influence. It is not a desert.
The drying of the soil we are concerned with is toward the end of the
growing season and during the dormant period. A plant that has just lost its
leaves by yellowing and withering should already be in relatively dry soil.
It should not be watered until the next growing season in most cases. If the
plant has had a good season with vigorous root growth then this root system
will help pull water out of the soil just before the leaves die down; the
roots are dying back at this point also. Dormant tubers should not be put
away wet so to speak but I don't know if humidity alone is enough to prevent
soil from drying "enough". This issue will vary between species and genera.
It is worth re-emphasizing that plants are best grown 'snug' in their pots
so that the soil dries out regularly and the roots can develop mainly around
the perimeter of the rootball, where there is better aeration and more
warmth. It is important in avoiding excess moisture whether the plant is
dormant or growing, especially with tuberous aroids that experience a
pronounced dry season in nature. I like to say that if you can master
watering (to your own needs) then you have mastered half of horticultural
practice.
There is probably an ideal moisture level for the dormant tubers of any
given species but there is also a considerable margin of error for us
growers. Sauromatum can grow here outdoors in gardens with winter rainfall
when it is dormant (and in St. Louis for that matter); conversely plants
like Amorphophallus gigas or A. titanum can suffer if the soil gets so dry
that the perennial roots die back. Perennial roots are often a good
indication that a plant receives or is adapted to off season rainfall (or
watering). Some tuberous aroids have them while others do not.
I hope this helps.
Dylan
On 14 December 2011 07:15, D. Christopher Rogers
wrote:
Hiyer, Dylan!
What are your local humidity levels? It seems that the more humid you are,
the harder time one will have keeping the soil in the pots dry.
Christopher
On Mon, Dec 12, 2011 at 6:38 PM, Hannon wrote:
Dear Marek,
The best protection for dormant tubers is the soil that surrounded them in
the growing season. It acts like a perfect cocoon. A tuber will have greater
exposure to pests and desiccation if taken out of its soil. The idea of
unearthing bulbs and tubers after the growth period persists in many
hobbyist circles and I believe it is the wrong approach in most cases.
1. Attentive culture should result in no pests in the soil at all. Such
pests should be evident in the growing season and treated then, especially
root mealy. When withered leaves are removed I push some soil into the hole
left by the petiole to prohibit entry by ants, mealies, etc. When the soil
dries out as the leaves yellow there should be no moisture at all at the
bottom of the pot. "Dry soil" is not as dry as you might think and will
retain some beneficial moisture for months while the plant is dormant. (This
can be demonstrated by allowing a few small weeds to stay in the pot and
observing them 5, 10 or 15 weeks later after zero watering). When they have
had a good season (in plastic pots) aroid tubers/corms will often distend
the pot so that it is firm and compact; this 'package' is the ideal state
for storage over winter (or summer).
2. At the beginning of the season I wait for new shoots to emerge and repot
then, when the plant is active. If they are slow to wake up I will water
well just ONCE and see what happens. If nothing happens after a few weeks
then I unpot and look for signs of trouble. Unless the new roots are well
along (with secondary branching) it is easy to transplant a plant starting
its growth. In fact, I often wait until a leaf is formed and then shift to
the appropriate next size pot. Usually this does not involve disturbing the
root ball at all. Note: some geophytes like amorphos and their kin seem to
need repotting every 1-2 years while others (including Biarum) can go on for
a number of years before new soil is needed. Keep in mind that any soil mix
used by a plant that is dormant half the year is only on duty for about six
months. Any soil mix that is exhausted in six months is hardly worthy of the
name. The addition of coarse sand helps the longevity of a mix
substantially.
It can be difficult to gauge the need of a plant for a particular pot size
until it is in full growth and it is impossible to know the vigor of a plant
until it is growing. Vigor-- not necessarily tuber size-- determines pot
size as well as watering needs and the two are closely related. I prefer a
smaller pot that needs more frequent watering rather than a relatively large
pot that takes too long to dry out. Soil in a container that takes weeks
rather than days to dry and justify the next watering is a sign that the pot
is too large for the root system. It is important to let the soil surface go
very dry between waterings, assuming everything else is in order. I grow
over 70 amorpho species and hundreds of other geophytes in 'cramped
quarters' and these techniques has been successful to date.
Dylan Hannon
On 12 December 2011 11:02, Marek Argent wrote:
Dear Hannon,
I keep all tubers dry when they're dormant, even I dont water them until the
new bud grows enough large to break.
As for the soil - should the tubers stay in the old soil during the dormancy
or should I change it as the roots wither
or when it starts to grow again?
In all the methods there are good and bad things.
1. Leaving the tuber in the old soil means leaving it with all pests and the
soil itself often remains wet too long at the bottom of the pot what may
cause rotting. Next season the tuber can start to grow too early and
repotting it while producing new roots may be fatal.
2. Repotting it shortly after the leaves wither - the new soil left dry for
a few months loses its moisture and structure, it turns into dust and sand.
So when is the best time to change soil in pots?
Marek
----- Original Message -----
From: Hannon
To: Discussion of aroids
Sent: Saturday, December 10, 2011 3:46 AM
Subject: Re: [Aroid-l] Cultivation of Taccarum
Agreed that keeping it in its pot when dormant is a good idea, as with all
geophytes. But Taccarum should be kept DRY when dormant. This is true for
probably most but not all tuberous aroids.
On 9 December 2011 05:53, wrote:
Your problem is taking it out of the soil, it needs to be kept in the pot
and moist at all times, also needs to be outside not in a window.
In a message dated 12/7/2011 11:47:28 P.M. Eastern Standard Time,
abri1973@wp.pl writes:
Hello,
I've had Taccarum weddellianum since 2005, every year it produces a leaf and
usually a "baby" tuber.
But... it doesn't grow in size almost at all, although the tuber very slowly
increases, the leaf is 20-30 cm tall every year.
I use regular pot soil, and the plant is fertilized with natural biohumus.
It grows in a southern window.
When it's dormant I store it without soil in the normal room temperature.
What do I do wrong? What should I do to make it grow larger?
Here are photos of my plant:
http://abrimaal.pro-e.pl/araceum/taccarum/weddellianum.htm
Please help,
Marek
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- Thomas Jefferson Memorandum of Services to My Country, after 2 September
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- Thomas Jefferson Memorandum of Services to My Country, after 2 September
1800
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D. Christopher Rogers
((,///////////=======<
785.864.1714
Crustacean Taxonomist and Ecologist
Kansas Biological Survey
Kansas University, Higuchi Hall
2101 Constant Avenue, Lawrence, KS 66047-3759 USA
http://www.kbs.ku.edu/
http://www.kbs.ku.edu/directory/d-christopher-rogers/
Associate Editor, Journal of Crustacean Biology
http://www.thecrustaceansociety.org/
Vice President, Southwest Association of Freshwater Invertebrate Taxonomists
SAFIT.ORG
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plant to it's culture"
- Thomas Jefferson Memorandum of Services to My Country, after 2 September
1800
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