Grammatophyllum culture: My experience with plants that have lost their roots

 

The aftermath of hurricanes Irma and Maria left most people in the island of Puerto Rico scrambling to secure the basic survival needs.  I my case, I was so busy at work, that for many months I could not pay attention to my orchids.   The hurricanes destroyed the forest canopy in my locale.  This produced wildly fluctuating temperature, humidity and light exposure.   Periods of extreme rain alternated with periods of almost no rain.  Many of my orchids could not adapt to the new circumstances and died.   Those that survived often suffered massive root loss.   Among those that lost their roots were my Grammatophyllums of the scriptum and elegans type.  As a result, they became much smaller, some plants divided into small groups of rootless pseudobulbs. 

Normally, Grammatophyllums are tough and resilient, but their tolerance was solely tested after the hurricanes.   To compound the problem the tags of most of them were lost.  So I took the remaining pieces and planted them in a variety of mounts to see in which ones they did better.   I have one advantage most people don’t enjoy, the humidity in my locale normally lies in the range that is good for tropical orchids. 

I planted the pieces I had in four different ways.   One was tied to a wire framework, with nothing else to provide attachment or moisture.  Another was put on a small plastic mesh pot filled with bark.  A third one was put on top of a metal wire basket.  Lastly one was tied to the bottom of a wire basket.  Before I go on, I have to explain what is a root basket.   Grammatophyllum often produces a mass of roots with many roots pointing upwards.  The purpose of these roots is to trap leaves and debris that fall on the plant as a source of moisture and nutrients.  A healthy plant often has a large root basket surrounding its pseudobulbs.  Many people affix their plants to tree fern plaques, or grow them in wooden baskets to allow the roots of the root basket to expand at will.  

 After a few years of care this is the results:  The one that was tied to the metal wire mesh has done better, it’s the one that has the most bulbs and the largest root basket.   On second place came the one on top of a metal wire basket, it produced small bulbs until it reached the edge of the basket, then produced the largest pseudobulb of them all.   Unfortunately, I put this one in a planter and it send a mass of roots into the pot next to it.  I had to rip it from the pot and in the process damaged its root basket, I expect it will recuperate quickly.  On third place is the plant growing attached to the bottom of a wire basket.  It has grown slowly, lost some pseudobulbs to rot and it still hasn’t started producing a root basket.  The piece that is growing on top of the plastic mesh pot filled with bark is the slowest growing of them all.  It only has two relatively small pseudobulbs and its yet to start producing its root basket. 

 From these results, I think it is clear that the Grammatophyllum prefer that their roots not be confined and will do better if their roots can grow at will and are exposed to air.  These plants are heavy feeders and need constant fertilization during their growth cycle for their pseudobulb to attain a large size.  High environmental humidity is extremely important in the case of plants that have lost their roots. 

Sometimes I use Styrofoam cups instead of foam chips or stones to increase drainage and aireation of the media in which large orchids will grow.

One of the problems of potting very large orchids is that there is the possibility that the large mass of potting media will retain too much water and become anoxic (devoid of oxygen), something that is lethal to orchid roots.   When I had to pot a Grammatophyllum speciosum, I put four styrofoam cups in the bottom of the pot.  I made many holes in the sides of the styrofoam cups to allow air to flow.  I poured the media, in this case bark, over the cups.  As you can see the Grammatophyllum developed a large and healthy root system.  I had to repot because the orchid had become too top heavy.  Because of this, when I pot Grammatophyllums I usually add a layer of gravel to the bottom of the pot to give it stability.  Unfortunately, these plants grow so large that they need the heaviest of pots to keep them stable.

Oncidium altissimum [Jacq.] Swartz 1800, with an unusual root basket.

This orchid is found in the wild in Puerto Rico, the United States Virgin Islands and in several islands of the lesser Antilles.  In Puerto Rico it is widespread except for the dry regions (Ackerman 2014).  I live in a forest near the town of Arecibo,  Puerto Rico.  When I hike through the forest I often see this species growing high up in the trunks of trees.  However from time to time I find seedlings growing in less sturdy locations.

In the case of this plant, it was growing in a relatively slender branch.  As the orchid grew in size it started building its root basket.  Root baskets in orchids trap leaves and organic matter.  Each new growth adds its roots to the basket.  The moisture and nutrients caught in the root basket helps the plant survive and produce new growths.

The part of the branch where the orchid was growing died and started decomposing, but because it was covered with orchid roots it didn't fall from the tree right away.  Since the decaying part of the branch no longer had the structural integrity to support the weight of the orchid, the plant found itself hanging upside down, still attached to the tree by its network of roots.  The new growth grew in the opposite direction of the older pseudobulbs, which now were hanging upside down.  The new pseudobulb produced roots that grew in exactly the opposite direction of the old ones.  The result is the unusual root basket you see in the photo.

Eventually, the roots of the orchid that were attached to the still living parts of the branch decayed and the orchid fell to the ground after a particularly windy storm.  I found the plant by the roadside.  I took the plant to my garden to observe how it will grow now that the only support it has is its own roots.

Ackerman, James. D. 2014. Orchid Flora of the Greater Antilles

My Dendrobium amethystoglossum lost its roots, so I did this...

Please note that I made slits on the side of the plastic pot to increase
both drainage and the circulation of air around the media and roots.

This Dendrobium amethystoglossum grew relatively well for several years in my garden and bloomed a number of times in that time span.  Unfortunately, last year the media began retaining too much water, this caused the death of the root mass.  When I noticed something was wrong almost all the roots were gone.  So I took the plant from its pot, trimmed away the dead roots, removed the decayed media from the meagre remains of the root ball and repoted it.   I used as media the hardest part of the trunk of the tree fern.  I cut the pieces of tree fern by hand into medium sized flakes.  The flakes were put on the pot so that they would make a relatively loose open mass that could be easily penetrated by the roots.  This part of the trunk of the tree fern is particularly resistant to decay so I expect it will last a while.  The orchid started growing in April and now it is producing new roots.  I expect that in the next two years it will have a good root system and will start producing larger canes.