Forced Re-Pot of C. purpurata

During this past week-end we had some high winds. One of the problems with growing orchids out doors is that when rough weather happens it happens to my orchids. Tall growing plants such as C. purpurata make great sails, and when there not secured to their growing place, topple to the ground. With a broken pot I am forced to re-pot.

The plant was potted in feb 2010 and was doing well. It was well contained in it’s pot, so I could have simply placed it in a replacement pot. But I thought I’d do a complete re-pot and attempt to show the progress. Each of the photos is a thumbnail, so clicking on a photo will show you a higher-resolution photo.   You’ll need to click the back arrow to continue on this page.

Take a look at the left most photo above. This is a cross section of the old potting material  used in the prior potting of this plant. Note the base of packing peanuts. The growing media is a combination of bark, charcoal, sponge rock, and tree fern. I’ll be removing most of the old growing meterial, and to facilitate removing the old media I’ll soak the plant. First I soak in a beach solution (1 cup/gal), then rinse, then a soak in water with a teaspoon of a rooting hormone. I use DYNA-GRO KLN  (second photo from the left). I select a pot that will handle the plants root mass. I soak the pot in a bleach solution. and finish by washing with a detergent.  (third photo from the left).   The final photo above shows the  root mass right after it’s removed from the soak.

The left most photo above shows the roots now freed of the packing peanuts. The saturated roots are pliable and will release the old potting material with the gentle persuasion of my finger tips. When I remove the old material, I like to work over a trash can or other container to catch the material as it falls from the plant. The next two photos show the roots with old material removed. Removing the old material from the middle of the root mass takes patience, but with practice you can easily move the roots and release the material with very few snapping sounds. The snapping sound is usually a broken root. Many growers will trim the root mass back. These older roots can continue to grow once cut or broken as long as the damage is not close to the rhizome. Knowing this allows me to be less stressed when I do damage a few roots during the removal of the old material. I also use a flow of water from my garden hose to ‘jet’ away the media. Note the right most photo above, you will see the new root tips, take care not to damage the new growth. This new growth will help to establish the plant quickly.

It’s my belief that many epithetic orchid need to be securely attached in order to root into the new pot. I’m now using large chucks of horticultural grade charcoal as my base in the bottom of the pot. The packing peanuts are also a fine choice for establishing the base of the pot. The desirable characteristics of  the base materials should include little or no moisture retention, provide very good drainage, and the base material should not breakdown readily. The base material of charcoal and clay pellets meets these characteristics and create a very firm base to rest the plant. Prior to placing the plant in the  pot, I work  my potting material inside the middle of the root mass. I accomplish this by holding the plant upside down and gently placing potting material around the root.  I set the plant in the pot and use a pot clip or two to secure the plant on the base. Don’t worry when some of the potting material falls from the plant when turning the plant upright.  The right most photo shows the plant in the pot. I situate the plant with the old growth snugged up against the pot  and the new growth an inch or so from the pot edge.

While most people use a mix when re-potting,my approach is to keep my potting materials separate and create the mix by adding them a little at a time, and alternating through each material. On this re-pot I’m using Hydroton clay pellets, sponge rock, charcoal, and tree fern. Hydroton is a name brand, you may also see these clay pellets under the name aliflor, or LECA. The clay pellets come in several sizes. I’m working with pellets that are about 1/4 to 1/2 inch in diameter.

The four photos above shows the progress of working first the pellets, then the sponge rock, then the tree fern. I push the materials into the cavities using a bamboo stick. I use the material in order of size, charcoal, then pellets, then sponge rock, then tree fern. I use a light tapping after placing each material into the pot. The tapping will cause the materials to settle into the roots. My goal is to fill all the cavities around the roots in the pot. Initially I’m using a  higher ratio of large material to fine material, and switch the ratio as I get near the top of the pot.

In the first photo on the left above I have rotated the pot to work on the other side. Notice the bamboo stick in this first photo, I’ve worked a path through the roots in order to have better access for my potting materials. Also note the pot clip I mentioned earlier.  The second photo from the left  is showing a completed layer of material. When I place material into the pathway  I created in the first photo, I initially work it towards the middle of the pot and up. As I work the material to fill all the voids I work to  pack the material . The third photo from the left shows a layer of sponge rock before I tap it and pack it. The right most photo shows the completed re-pot.