Angraecum sesquipedale

[zaphod]

Dear Orchid Doctor:

I read the care sheet on cattleyas so that I could understand what my
Darwin's orchid needs to bloom. I bought it last year (December) from
an orchid show in San Francisco and it was in bloom. This year it has
been living in three different homes but always inside. I currently
have it in a room that faces northwest, next to the kitchen, with some
strong light coming through, but no direct sun. I have never put it
outside. I water thoroughly as needed with diluted fertilizer for
cattleyas. It is potted in lava rocks and I also keep it on a
humidity tray.
The leaves are med-dark green and most are pretty stiff. The roots
are greyish and dry. The leaves have a white residue, which I ignore
as hard water from misting, and some of the roots have white spots.
Overall the plant is alive and well, but no sign of a new spike for a
flower this year. I am new at this and would appreciate any advice
you could give me to get it to bloom!

Thanks very much-
~sabine

[orchid doctor]

Dear Sabine:

I cannot recall any San Francisco shows that take place in December,
but I do recall there were young Angraecum sesquipedale for sale at
our February show.

While there are a few similarities in culture to Cattleya, there are
also many differences which may account for a failure to bloom. This
Angraecum is found near sea level and so is a warmer growing orchid
than most Cattleyas. It would prefer its nights to be at least 65
degrees, and would not be happy with nights below 60 (I don't think it
is ever appropriate to put this plant outdoors in San Francisco
proper, though perhaps in the inland valleys or South Bay it might
summer outdoors) It will be happiest with days around 80. It will
tolerate days of 68-72 (and grow and bloom) but they are not ideal.

It does not want to dry out as much between watering as a Cattleya
does, though it can be allowed to become dry between watering in the
winter, but should never remain dry for more than a day. Otherwise it
should be watered when the potting mix is still barely moist. If this
plant is mounted, it can be watered as soon as the roots are dry,
which would be every day in the summer and every few days in the
winter. In a pot of course, watering would seldom be more than twice a
week, and often only once a week.

It is a shade grower in nature, unlike the Cattleyas which grow at the
tops of the trees. In home cultivation some direct sun in the morning,
or very bright light is needed, so the plant should be in (not near or
accross the room from) the proper window. an unimpeded north window
would work, as would a south windoe with a light curtain in the winter
when the sun angle is low. East windows would work as well. Light is
often the crucial element for blooming an orchid in the home, and many
people do not give orchids as much light as they need for this high
energy process. Your window sounds good, so long as the plant is in,
or very close to the window, not just "in the room".

Fertilizer helps as well, but is not crucial. This plant would
appreciate being fed every second or third watering throughout the
year, using any complete, well balanced product mixed at 1/2 the
recommended strength (maybe 1/4 strength in the winter).

As a winter bloomer, it is not too late for an inflorescence to appear
at this point, and it may well be in bloom by February or March.

Angraecums do not like root disturbance at all. They will need to be
repotted every third year or so, but this should only be done in the
spring or summer (when there is active root growth), and it needs to
be done gently!

Sincerely,
Dennis