questions and answers
10 Orchids JANUARY 2011 www.AOS.org
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DENDROBIUM ANOSMUM
Question I am a novice in the world
of orchids. I live in western South Dakota
(close to the Wyoming border) in a centrally heated house. I have a Dendrobium
anosmum that I bought two years ago. It is
potted in sphagnum moss. Last year it did
not produce any flowers but it did grow
several keikis (plantlets). I never stopped
watering it. This year I really want to see
some flowers. My plant looks healthy. Do
I stop watering it? Do I mist it once in a
while? The heater is already on because the
temperature dropped below 40 F (4 C) last
night. I planted last year’s keikis in a small
pot and they look healthy. Do I treat them
same way or do I continue to water them?
I have one Dendrobium nobile as well.
Do I stop watering it? I grow my orchids on
windowsills in a south-facing room that has
three big windows on the south wall. — Hasina Ahmad, Spearfish, South Dakota.
Answer Unlike Den. nobile, which
requires several weeks of temperatures
below 55 F (13 C) to induce flower initiation, Den. anosmum does not need low
temperature to trigger flower induction.
An air temperature lower than 65 F (18 C)
greg allikas
about the peat moss you are using on
your intergeneric oncidiums. After some
difficulty, I secured a coarse peat moss
from a German source and the Paph-roc
expanded perlite. This mixture holds
more water, at least in the beginning, than
the mix of bark, rice hull and milled peat
I was using. It also seems to give up its
moisture more quickly than my previous
mixture.
I read in the December 2010 Orchids
(page 670) about the moss growing atop
your plants. I’ve been buying plants from
Matsui, mainly phalaenopsis, and I have
not seen the moss, but you cite wet pots
without rotting the roots as a key to success. How often do you water the coarse
peat moss mix for intergenerics? I realize
your conditions are different from mine,
but your regimen would give me some idea
about good cultural practice.
Also, a grower in Apopka, Florida,
told me she had taken your course on phalaenopsis and reported that you sprayed
something on phalaenopsis, probably at
the time of spiking, to encourage double
spikes. Would you share the name of
the product? I tried a product from one
of the chemical houses two years ago,
but didn’t notice any additional spiking.
— Don Baker.
Answer The
coarse peat medium
that I described in
the September issue
of Orchids magazine (page 490) allows for lots of air
space in the medium
and does not experiYin-Tung Wang
ence much compaction. It does not hold as much water as the
milled or finer peat, either. The green moss
grows on the medium of our oncidium and
intergeneric orchids only, not on the medium
of phalaenopsis. We water the oncidium and
intergeneric orchids as needed before the
medium becomes too dry. Keep the medium
moist at all times so that the plants do not
stress. The long-held widespread belief of
letting an orchid medium become dry before
being rewatered is obsolete.
The chemical you would use on phalaenopsis to trigger multiple spiking is
called Configure. — Yin-Tung Wang, PhD,
Director of R&D and Production, Matsui
Nursery, Salinas, California, and Adjunct
Professor and Graduate Faculty, Department of Horticultural Science, Texas A&M
University (e-mail ywang@ag.tamu.edu).
[1] A vegetatively propagated clone of
Phalaenopsis Yu Pin Pearl (Ever-spring
× Musashino) 18 months out of flask.
Following treatment with a cytokinin plant
hormone, plants of this clone are capable
of producing multiple spikes on relatively
young plants. The hormone does not
guarantee how many spikes may be
produced by each and every plant and
variety. However, after the treatment,
a much higher percentage of plants
produce two or more spikes. The plant
in flower (left) was moved into a warmer
greenhouse at an earlier time. Even
in the same greenhouse, some plants
come to open flowers sooner than others.
Grower: Matsui Nursery.
[2] Low temperatures are not necessary
to get Dendrobium anosmum to flower.
The clone ‘Riverlane’, JC/AOS, is shown.
Grower: Jean Wilson.
would do, but 60–64 F (16–18 C) is better. Plants of this species do not shed their
leaves at these temperatures. However,
at lower temperatures, particularly those
below 50 F (10 C), leaves will turn yellow
and fall. Because your plants have grown
well, water them as usual. If the leaves have
abscised, then you do not want to keep the
moss wet at all times. Let it come close to
dryness (but not bone dry) before watering
again. No misting is needed. You should treat
your Den. nobile the same way. If you see the
pseudobulb start to shrivel, it is an indication
that you had not watered it quite enough.
Applying fertilizer from this point on does
not enhance flowering. If your plants still
have green leaves, applying a quarter-strength
soluble complete fertilizer will help maintain
green leaves. — Yin-Tung Wang, PhD.
yin-tung wang
PEAT MOSS
Question I queried you earlier