This is one of the most common questions I receive from
orchid growers. Another related question
is why do Stanhopeas not bloom
consistently each year? The answers are not necessarily straight forward and
all encompassing. Some of the reasons why
Stanhopeas do not bloom are because
they are too immature to bloom, are planted in the incorrect media or
containers, the general growing conditions are not understood well, and that
they are not given proper care.
Stanhopeas only
bloom on mature pseudobulbs, so if you purchase a seedling instead of a
division of a plant, then it may be a few years before your plant blooms. Small seedlings of only two years of age may
take five or more years to mature.
Recently divided plants may not bloom for a year or two, and take time to
recover depending on the size of the division and the time of year that the
division was taken. Repotting or
re-basketing may also delay bloom of Stanhopeas
for a year or more. Several growers have
reported that they have no setback in bloom times from dividing or repotting Stanhopeas. However, I have been following this more
carefully over the past few years and have recorded approximately 50 percent of my Stanhopeas negatively impacted due to
division or repotting. Most of the ill
effects are lower flower counts on the inflorescences, or early termination of
new inflorescence growth.
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Stanhopea panamensis - second flowering of the
year in December after main flowering in October. |
It is advised to grow Stanhopeas
in baskets because they produce pendent inflorescences that grow through the
potting media . I have received several Stanhopeas from people who did not want
the plants any longer because they could not get them to bloom. When I received the orchids I found
they had been grown in pots, not baskets.
When I repot the plants into a basket, I often find several old
inflorescences that could not grow out of the pot from the last flower
season. After re-basketing, the plants
began to flower normally each year.
Knowing the proper care provided to the
species of Stanhopea you are growing often
leads to an increase in flower production.
Some species such as S. annulata, S. avicula, S. candida, S. cirrhata,
S. ecornuta, and S. grandiflora (including
several others) require more tropical night temperatures throughout the year and
bloom best when winter night temperatures do not drop below 65F (18C). Other Stanhopeas
inhabit areas where they receive less water and more sunlight during the winter
months. These Stanhopeas that require a rest period include S. hernandezii, S. insignis, S. jenischiana,
S. leitzei, S. maculosa, and S. martiana. I usually place these Stanhopeas under a roof overhang or
under a plastic roof during the winter so that no rainfall can penetrate the
growing medium. I then keep these
sparingly moist, but never let them completely dry. I start regular water of these species in mid
spring, when growth starts. For these Stanhopea, the dryer conditions and
increased light during the winter tend to force them to enter into a rest
period that they require in order to flower well in the following spring/summer.
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Stanhopea panamensis - close up.
Once your Stanhopeas increase in size they
often will bloom more than once a year. |
One common problem Stanhopea growers share is that they
are unsuccessful in consistently blooming their Stanhopeas in greenhouses.
In fact, Barney Greer mentions several species (S. florida, S. maculosa,
and S. platyceras,) that he had
growing in a greenhouse in Sydney, Australia that refused to bloom until he
divided the plants and placed them to grow outside. During the next flowering season the plants
began to flower regularly. The reason
why this may occur is that some species of Stanhopea
bloom more profusely with a 20-30F (approximately 10-15C) degree shift between
day and night temperatures. These shifts
in temperature are best achieved by growing the orchids outdoors in the spring
and summer. Since several species of Stanhopea can grow and bloom well
outdoors in southern California, I choose to grow my collection outdoors year
around, and then shelter those that need either more warmth, or less water in
the winter months. If you cannot grow
your Stanhopeas outside the entire
year, try growing them outside in the spring and summer months. Most growers that have tried the technique of
growing Stanhopeas outside when the temperatures are warm enough have had an increase in success flowering their plants.
Additional care that can cause inconsistent flowering
includes too little water during the growing season, or being placed in too
much sun, and not enough humidity. When
I first began growing Stanhopeas, I
placed them in a specific location that received dappled sun throughout the
day. The tree that provided the shade
had lost some foliage and branches and one of the Stanhopeas was severely burned.
The plant could no longer grow in that location, with too much sun and
not enough water and humidity throughout the day. I repotted the Stanhopea and placed it in more shade. The plant slowly recovered and new growth
began, but after that improper care, the plant did not bloom for five years. Just remember that if your plant has some
type of a setback or improper care for some time, it may not bloom for a year
or more.
Some individuals find that fertilizing Stanhopeas more can increase flower production. I only fertilize to ensure that the plants
are growing large enough and the pseudobulbs are mature enough to flower. Other than this, I have found that no other
fertilizing is necessary to spur plants to bloom.
Too much shade is usually not a problem, but could be the
cause for some Stanhopeas to not
bloom. I usually keep my Stanhopeas on the north side of my house
and they either receive dappled sun the year around or indirect sun with the only
shade coming from the building. I often
provide a little extra shade by stretching saran cloth over the growing area during
the summer months and when temperatures are very high (above 90F or 32C).
If you follow these general guidelines, you should be able
to increase your chances that your Stanhopeas
will bloom, and do this consistently each year.
Being patent is a requirement though, and it may take several years for your Stanhopeas to produce good sized growth
in order to flower. For reference and
indications that your Stanhopeas are
growing appropriately, see the post 'How do you know your Stanhopea is happy?'
