Stanhopea Inflorescences 2013

After our colder than normal winter, spring has been warmer with close to normal temperatures.  This warm and mild weather has increased the speed of the inflorescence growths for early summer, and it appears that the Stanhopea will be blooming on time this year.  Some Stanhopea are producing additional inflorescences this year, and it is always with a sense of satisfaction that the effort you put into growing a good size plant in one year, pays off with more blooms the following year.

As plants continue to mature they should eventually produce additional growths each year that will lead to an increase in inflorescences.  This may take some time to accomplish and patience is definitely a virtue when growing Stanhopea.  For example the S. tigrina var. nigroviolacea ‘Predator’ from my post last year with eight inflorescences produced thirteen this year.  However, two aborted which happens occasionally due to physical damage or a fungal pathogen.  In addition the S. embreei from last year’s post has three flowers on the inflorescence this year with two more inflorescences coming.  It is good to see a plant that I purchased only two years ago continue to grow well and produced more blooms each year.

S.tigrina nigroviolacea 'Predator"
with eleven inflorescences

S. embreei inflorescence with three buds

If you miss the growth of an inflorescence that is at the top of the growing medium and it seems to be attempting to grow back down into the medium, you may want to insert a plastic tag beneath it to help direct it out of the basket.  I have found that allowing an inflorescence that has already surfaced at the top of the growing medium to grow back down will often result in the failure of the inflorescence to mature and bloom.  Approximately 50% of the inflorescences that grow out of the growing medium and then back in, often rot and never bloom for me.

The following will bloom later in the summer and include a different form of S. tigrina var. nigroviolacea that has not bloomed for me before, an S. oculata that refused to bloom last year, and a new inflorescence is emerging on S. intermedia that I am looking forward to seeing for the first time.



S. intermedia emerging inflorescence

 

Stanhopea Diseases

 

Stanhopea are relatively easy to grow and have few problems when cultured properly.  The most bothersome problem I have found is brown spot and anthracnose in some species and hybrids.  I have provided the following partial list of diseases that I have found susceptible by Stanhopea.  However, there are other diseases and viruses that can affect Stanhopea similar to other orchid genera.  I have included a link at the end of the text for further assistance.

Bacteria:

Acidovorax (Pseudomonas) –This starts as a blister that is small, green/brown and eventually enlarges to a brown or black dried and sunken spot.   Bacterial Brown Spot is a water –borne pathogen that thrives in warm and moist conditions.  Increase air circulation and reduce overhead watering.  Spray the plant with a bactericide (e.g., Physan and copper solutions).

Fungus:

Anthracnose (Colletotrichum and Glomeralla ) This fungus affects the leaves and turns the apex brown and then moves to the leaf base.  This often occurs as bands across the leaf, and for me occur often in the early spring with the weather warms and it is still moist.  This is a fungus that is common when air movement is low, temperatures and humidity is high, and light levels are low.  Use a fungicide such as Cleary’s 3336 to prevent further infections.

Black Rot (Phytophthora cactorum and Pythium ultimum) This is a fungus that is present in some orchids and often attacks new leaves and growth.  This infects the vegetation and causes translucent spots and then the tissue dies (necrosis)and turns black in color.  I have not had a problem with black rot on Stanhopea, but rather other orchids in my collection have been susceptible to this fungus.  Removal of the infected plant parts should be accomplished and standing water should be removed in the growing area to reduce infection.  A fungicide such as Cleary’s 336 can be used to prevent further infections.

Botryis is a fungus that often produces brown spots on orchid flowers which are dead cells (necrosis).  The fungus overwinters on dead and rotting vegetation.  Make sure to keep the growing area clear of dead vegetation and lower humidity below 90 percent.  This is not a serious threat to the orchid plant but disfigures the flowers.

Cercospora Leaf Spot (Cercospora spp.) This often begins as a yellow spot under the leaf and then is noticeable on the upper surface.  This infection spreads through the leaf and the spots are sunken and turn black or brown.  Infected leaves fall prematurely. This is a fungus that is common when air movement is low, humidity and moisture on leaves is high.  Use a fungicide such as Cleary’s 3336 to prevent further infections.

Viruses:

Stanhopea ringspot is a virus that causes yellow spots and rings that are circular or diamond shaped on a green leaf background.   The symptoms occur on older leaves or mature leaves.  This virus has been noted on some Stanhopea, though it  is not common.  I have not had much experience with viruses in my collection and tend to keep my growing area clean and ensure that all my tools are disinfected before each use on a different plant.  If you notice that there are signs of virus on your plant, isolate it from the rest of your collections and seek advice from a competent orchid grower.

For further reading see the AOS Orchid Ailments

Stanhopea Summer Culture Checklist

 

The spring season of 2013 was warm and mild.  It has been warmer than the spring of 2012, so this helped the Stanhopea recover from our cold winter.  Due to the warmer and dry spring I have had less problems with fungal and bacteria growth on leaves compared to the rather cool and moist spring from last year.  Even with the warm spring, inflorescence production seems to be approximately two weeks late from last year.  I attribute this late inflorescence growth to our colder than normal winter.  Perhaps this warmer spring/summer weather will allow the orchids to speed up inflorescence growth.

·       Continue watering all Stanhopea regularly and keeping them moist.  I usually water my orchids three to four times a week under normal temperatures.  If temperatures rise above 90°F (28°C) and humidity is low I mist and lightly water every day.

·        Continue fertilizing all species regularly.  I often reduce the manufacturer’s recommendations to one third or one half and fertilize every week,  or what is known as weakly-weekly.  Stanhopea can be rather heavy feeders when they are in active growth.

·         Weed baskets to prevent ferns and other plants from taking up space in baskets.

·        If you grow your Stanhopea  in a sunny area or a greenhouse that receives strong sunlight you may want to place saran shade cloth over the growing area in early spring and summer before the sunlight becomes too strong for them.  You may also want to consider moving the Stanhopea to another shadier growing area for the summer.

·        If you know temperatures are going to increase and humidity levels drop, you may want to consider moving a Stanhopea that is coming into bloom to a shady more humid area, or as I often do onto my covered patio.  That way I can enjoy the flower show right from my window.  This often prevents early desiccation of flowers and they tend to last the average three to five days instead of just two.

·        In late spring/summer make sure to check for growing inflorescences and ensure that their growth is unimpeded by other plants or the basket.  If need be place a plastic label underneath the inflorescence to help direct the growth out of the basket.

·       Use of a methaldihide product or an organic substitute such as "Sluggo" is advised on a weekly basis at this time to prevent slugs from disfiguring new growth and impacting new inflorescence and bud growth.  I often use a product called “That’s It” that is a granular form and therefore leaves less residue in the growing media.  I am currently testing "Sluggo" as a more organic method of slug control.

·        Keep a careful eye out for spider mites as the spring continues and our weather begins to warm and dry out.  Small yellow spots on the foliage signal that these pests are active on your Stanhopea.  Spray infected areas with rosemary oil spray or an insecticidal soap to kill the pests as soon as possible to prevent them from damaging the plant further and spreading to other orchids.

·        You should also be diligent in keeping watch for fungus infections at this time on leaves.  Several fungus attack leaves when humidity is high and temperatures are warm. Black or brown spots of leaves and yellowing of leaves in odd patterns are usually the cause of fungus or bacterial infection.  Treat with a fungicide or bactericide.  I often use Physan 20 to deal with the problems and prevent further damage to the plants.

·        The warmer temperatures and reduced breezes combine to cause fungal infections such as black spot on some Stanhopea species and hybrids.  The key to reducing this problem is to make sure your Stanhopea are grown in a breeze way that gets constant air flow, or to place a fan in the growing area that produces a very slight breeze at all times.  This will prevent the fungus from settling on the leaves and disfiguring them.   The leaf fungal problems do not impact the health of the plant to a large degree but do look unsightly.

Stanhopea Pests

Stanhopea are relatively pest free orchids when compared with other genera.  The common pests are snails/slugs and spider mites.  For me the snails/slugs are a constant battle, and are the more serious pests.  These mollusks can damage new growth, inflorescences, and flowers.  They usually do not have any more of an impact on a plant other than cosmetic damage, though long term damage can occur if they continually eat new growth and prevent the plant from growing well.

Bush snails (orchid snails)
from Orchidboard.com

I use metaldehyde based snail and slug bait (e.g. That’s It) to control these pests that is a granular form, and doesn’t leave a meal residue in the pots and baskets. I also have been recently trying “Sluggo Plus” suggested by a blog visitor.  This product breaks down into iron and phosphorus which plants benefit from, and it is less environmentally damaging. "Sluggo" seems to be a good product to use and does not adversely impact children, pets, and wildlife in the amounts used as directed.

Spider mite spots on leaves of Stanhopea.
From Orchidboard.com

Spider mites on underside of plant
leaves. From Got Pests? website
at Maine.gov

 

Spider mites can be a problem for Stanhopea and are generally noticed when light yellow spots appear on the leaves in large numbers.  I have had very few problems with spider mites in my collection perhaps because I grow most of the Stanhopea outdoors where spider mites have to deal with predators.  That being said, environments that are low in humidity and dry often allow plants to harbor spider mites. The best control I have found for these is to apply a rosemary oil based mite control (e.g., SNS-217) to the leaves and pseudobulbs every few weeks.  This treatment removes the spider mites and then you can ensure that they don’t return by increasing humidity in the environment and checking your plants often to spray again when necessary.  These rosemary oil based sprays are organic and pose less of a threat to pets and wildlife.

Stanhopea Spring 2013

Spring is well under way and Stanhopea are showing signs of growth and preparations for inflorescences. While some Stanhopea have just begun new growth, others have just completed winter growth, and still others have not grown since last fall.  It has been interesting to note how varied the timing and duration of growth Stanhopea exhibit as my collection has increased.  Growth in Stanhopea can be so variable between species and even sometimes between different forms of the same species.  Some of the easiest species of Stanhopea that I find to grow (S. oculata, S. tigrina, and S. wardii) grow intermittently throughout the year, taking short breaks between growth cycles.  Other Stanhopea such as (S. anfracta, S. gibbosa, and S. panamensis) begin a growth cycle in early to mid-spring, and then again in summer before flowering.  Other Stanhopea (e.g., S. insignis, S. lietzei, and often S. shuttleworthii) don’t begin growth until summer and then only produce one cycle of growth. 



Stanhopea tigrina "Glory of Mexico" with new maturing growth from late winter (left).  Stanhopea posadae with new growth started in early spring (center). Stanhopa anfracta with new growth started in spring (right).



These differences between the growth cycles of different species may be due to cultural conditions, or the maturity of the Stanhopea plant.  The species that grow intermittently through the year may be because they are the best adapted to the growing conditions that I have, and thus grow almost continuously.  In addition, these Stanhopea that grow well may be doing so because they are some of the largest specimens that I have and happily grow throughout the year.  This latter option may not be very consistent because two of my large Stanhopea (S. ruckeri and S. shuttleworthii) only produce one growth cycle per year.  It will be interesting to see if these observations of growth cycles remain consistent or vary over time and as the plants age.  It would be appreciated if those of you who have different growing conditions than mine (e.g., greenhouse conditions or a tropical climate) could post some of your observations.  Knowing when Stanhopea start new growth cycles and when they bloom allows us to determine the best time to transplant them (either spring or fall) depending on the species.  I usually attempt to re-basket Stanhopea just before a new growth cycle begins while the plant is dormant, and either before or just after flowering for the year.

Stanhopea frymirei (left), Stanhopea impressa (center), and Stanhopea nigripes (right) with new growth starting in mid-spring.

Repotting Stanhopea

 

             Stanhopea can be very rapid in growth and often need repotting every two years.  In fact, I have some forms that grow so quickly that they need repotting after only one year.  Seedling Stanhopea have been the slowest growers for me and may not need repotting as frequently, though large divisions can outgrow their containers rapidly.  I often use the term re-basketing to describe the repotting process for Stanhopea because mature specimens are grown in baskets.  Baskets are the most common containers because Stanhopea produce pendent inflorescences that either grow downward through the growing medium or along the top of the medium and out of the basket.  Immature Stanhopea can be grown in pots until they are mature enough to bloom.  It is much easier to care and grow immature Stanhopea in pots because they can be kept moist, thus preventing large shifts in the wet/dry cycle.  For this reason I usually do not place an immature Stanhopea into a basket until it will easily fit into a 6 inch (15 cm) one.

When to repot or rebasket

                Once Stanhopea reach a mature size they can be re-basketed every two years because they usually fill the container, or the growing medium begins to break down. However, if your intent is to grow a trophy Stanhopea in a large basket then you may be able to delay re-basketing for three or four years. For smaller Stanhopea, I usually don’t have to wait until the pseudobulbs fill the container, but rather if the new growth begins to appear at the edge of the container, then I determine that it is time to re-basket.

                There are two times of the year that are the best to repot or re-basket.  I usually like to repot in fall because the majority of the Stanhopea have bloomed and there is little chance of damaging a developing inflorescence.  Early to mid-fall seems best for this type of repotting.  The second best time I find to repot is in early spring after growth begins but before inflorescences have initiated. This also coincides with a time before major root growth, so there is little chance of damaging new roots.

Materials

The materials needed for repotting or re-basketing are rather easy to obtain.  These materials include either pots or baskets, growing media, basket lining material, cutting tools, plastic  labels and a disinfectant (Physan 20).  Growing media includes small seedling or terrestrial mix and Cattleya mix that I soak overnight in a mixture of Physan 20 and water to ensure that the media is sterile, and allow it to remain moist for potting purposes. If the potting medium is of excellent quality, then there will be few pieces of wood or poor quality bark that are included in the mix.  However, if you are unsure of the quality of the growing medium you can soak it overnight, and allow the poor quality bark to sink to the bottom of the container while retaining the good quality bark at the top.  You will want to do this before charcoal and perlite are added to the mix.  New Zealand moss is also used as growing media for seedling and small Stanhopea.  For specific growing medium details see the Stanhopea Growing Media post.  There are also some basket options listed here: Stanhopea Containers.  You will also need a label and a permanent marker to make sure that your Stanhopea remains correctly identified. Sterile razor blades or scissors and cutting tools are necessary to prevent transmission of viruses and bacterial infection from one plant to another.  It is always a good idea to sterilize your tools, pots, and potting media especially if you have invested a good deal of time and money into your orchid collection.  Make sure to sterilize your cutting tools between use on each individual plant.



Polyethylene 6 inch (15 cm) basket (left). Same basket lined with green moss and allowing a
pocket in the center where the plants roots can be placed (right).

The Process

           When it is time to repot a smaller Stanhopea this is a rather simple process.  I make sure I have a pot that is at least 1-2 inches (2.5-5.0 cm) larger in size than the pot I currently have the plant growing in.  I then have the appropriate growing medium available to fill the new pot. 

Seedlings

If the Stanhopea is a seedling and is planted in moss, the old moss should be carefully removed from the roots.  If the Stanhopea has grown through the media well it may be difficult to remove all of the moss from the roots, but try to remove as much of the old material as possible to prevent it from rotting the roots and pseudobulbs in the future.  Remove any dead roots with a sterile razor blade or cutting tool.  You can now place new moss around the root ball and fill the bottom of the new pot with approximately 1 inch (2.5 cm) of moss.  Place the root ball of the orchid in the new pot and position it so that the bottom of the pseudobulbs are at the same level as, or just below the top of the pot, and fill the remaining space in the pot with extra moss.   Make sure to water the medium so that it is able to keep the plant moist.

Stanhopea frymirei seedling needing new moss to be added to the pot. 
This is one of the difficulties of growing Stanhopea outdoors where birds
and other animals steal the moss from pots to make nesting material.

Small Stanhopea

                Repotting a small Stanhopea is similar to seedlings.  Remove the orchid from the old pot and remove as much of the old potting medium to prevent rotting of pseudobulbs and roots.  Remove any dead roots with a sterile cutting tool.  Select a pot that is at least 1.0-2.0 inches (2.5-5.0 cm) larger than the old container and fill the bottom with 1.0-2.0 inches (2.5-5.0 cm) of growing medium.  Place the root ball of the orchid in the new pot, and position it so that the bottom of the pseudobulbs are just below the top of the pot, then fill the remaining space in the pot with growing media.   Make sure to water the medium so that it is able to keep the plant moist. You will probably not need to water the orchid again for a few days after repotting.
 

Stanhopea oculata unpotted from a 4 inch (10 cm) pot (left).  Close up of roots of
S. oculata showing good root growth, and potting mix that should be removed
from roots before repotting (right).

Large Stanhopea

Re-basketing a larger Stanhopea requires additional materials and patience.  Removal of the Stanhopea from an old basket often requires cutting of the old basket material away from pseudobulbs that have grown through the basket.  If the Stanhopea is large enough for you to divide it you can split the orchid into several divisions with four to five pseudobulbs per division, making sure that this includes three or more pseudobulbs with leaves.  Once you have removed the Stanhopea from the old basket and/or divided it, remove as much of the old growing media as possible from the roots.  Use a sterilized cutting tool to remove any dead or damaged roots.  Choose a good size basket that will allow for 2 years of growth, approximately 2.0-3.0 inches (5.0-7.5 cm) larger than the division you are planting.  Line the basket with material to keep the growing medium in the basket (either coconut fiber, green moss, or paper bark, etc.).  Once the basket is lined, then place 1.0-2.0 inches (2.5-5.0 cm) of growing medium in the bottom of the basket.  Insert the root ball of the Stanhopea and fill in with growing media so that the bottom of the pseudobulbs are approximately 0.5-1.0 inches (1.2-2.5 cm) below the top of the basket. This is accomplished to allow the growing media to cover the bottom of the pseudobulbs so that most of the inflorescences will grow down into the medium.  However, some species allow the inflorescences to grow along the top of the growing medium, so this position allows inflorescences a good position near the surface as well.  Fill in the rest of the basket with the remaining growing medium, pressing gently to ensure that all large void spaces are filled with media.  I do this with my fingers instead of a potting stick because I tend to damage the roots more with the stick.  Make sure to wash your hands thoroughly between each re-basketing of plants to ensure everything is kept sterile.  Once the orchid has been repotted, water well and place in the shade for a few days to a couple of weeks.  Large Stanhopea that have recently been repotted may not need to be watered again for a few days or more if the weather is cool and moist.

Stanhopea oculata after repotting into a 6 inch (15 cm) basket (left).  The same
S. oculata approximately 1 year after repotting (right)

 

Stanhopea Growing Media

It has been stated by several orchid growers that Stanhopea will grow in almost anything.  This includes rock and pumice and other non-organic materials to organics. Barney Greer wrote that another grower used pure horse manure as growing media for Stanhopea.  I usually avoid using rock and pumice because this adds weight to an already heavy basket – especially for large trophy Stanhopea.  That being said I have found Stanhopea to grow best in a few types of growing media including orchid fir or redwood bark seedling mix, and medium or Cattleya mix, and New Zealand moss.

Fir and Redwood Bark Seedling Mix

I use this mix for smaller unbloomed Stanhopea or ones that will be moved into their first baskets.  I also use this mix to top off baskets that I have of mature specimens to keep the upper layer of the basket moist in my dry environment.  The seeding bark mix is a mixture of 60% 0.25 inch (0.63cm) fir or redwood bark, 25% 0..25inch (0.63 cm) pumice, and 15% activated charcoal.



Seedling Redwood Mix

 Fir and Redwood Bark Cattleya Mix

This mix is used for most of my medium to large Stanhopea that are grown in 8 inch (20 cm) and larger baskets.  This mix holds moisture but allows enough air and prevents overly moist conditions for Stanhopea that need a dry rest period during the winter months.  The Cattleya mix is a medium bark that is 60% of the mixture with 0.50 to 0.75 inch (1.3 to 1.9 cm) fir or redwood bark, 25% 0.25 inch (0.63 cm) pumice, and 15% activated charcoal.

Cattleya Redwood Mix

New Zealand Moss

I use this moss to provide consistent moisture in and around the remaining roots and base of the pseudobulb. This moss is especially useful for bare root plants that I often receive as imports or from divisions.   Most imports are  bare root, so it is important to keep the remaining roots moist to facilitate new root growth from the pseudobulbs.  I also use this moss as a first potting medium for 1-2 year old seedlings that have small fine roots and need constant moisture to remain viable in my dry environment.  This moss is a little more expensive than other types of mosses, but it is worth the extra cost for the consistency of the medium, and for the superior water retention.  If you have the extra money to purchase this moss and have difficulty in keeping your Stanhopea moist, then you can use this as the sole growing media for your orchids.

New Zealand Moss

 

 

Green Moss

I use green moss to line the baskets of most of my Stanhopea.  It has a consistent texture, and is attractive.  It is also relatively inexpensive and easy to obtain.  The moss also allows the inflorescences of Stanhopea to pass through easily and mature.  This moss holds the growing medium in place in the baskets, while also preventing dessication of the roots because it does hold moisture in after watering.  I usually place approximately 1 to 1.25 inch (2.5 to 3.2 cm) thickness of the moistened moss around the basket and make sure that it is thick enough to hold in the growing media firmly. 

Green Moss Basket Liner

 

Other Basket Liners

Several other basket liners can be used for Stanhopea.  If you have the money you can always use New Zealand Moss to line baskets and it has similar properties as green moss for this use.  Pre-manufactured coconut fiber liners are also available and are relatively inexpensive and easy to install. Just drop the coconut liner right into the basket and you are ready to start placing the media and Stanhopea in.  Remember to buy the non-plastic lined coconut fiber liners so that this will allow the inflorescences to pass through the liner easily.  Other liners that have been used include a few sheets of newspaper.  Though I have not used newspaper for this purpose, I understand that the raw look of the paper fades with time and still allows the inflorescences to pass through the paper.  I find the look of the newspaper to be a little unnatural, though it is more ecofriendly to recycle in this fashion.  Stanhopea growers in Australia have used paperbark from Eucalyptus, Melaleuca, and Tristania trees to line baskets.  If done properly and not applied too thickly, this allows the inflorescences to pass through the gaps in the bark while still holding in moisture and the growing medium.  I am currently attempting a few baskets lined with Tristania paperbark so see if it works for me as well.  The paperbark is more natural looking than newspaper and is relatively accessible from landscape trees in southern California.  I am fortunate to have a large Tristania tree in my landscape that provides rather nice quality paperbark for free.


Coco Fiber Liner