Saturday, April 27, 2013

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)
 

Monday, April 8, 2013

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