Encyclia culture: Potting with stones, getting to the nitty-gritty with Encyclia alata

                There are four ways I use stones for potting.  The most common is as a layer on the bottom of the pot, to provide weight to make the pot more stable for orchids that produce towering, heavy inflorescences that dwarf the plant and can easily overturn it.  This also helps ensure that the mix drains well.

                Sometimes I use them in the pot to have something to hold the orchid fixed in place.  I usually do this when using coarse potting media that initially provides little stability to the plant.  In this case I tie the plant to a stone and place the stone into the mix.  “A wobbly plant is a dead plant” as my friend Jose Oliveras uses to say.   The stone provides the plant with a firm anchor until its roots can get a grip on the media.

In rare cases, I use it as potting media for particular plants that are very intolerant of any potting media that when it decays starts retaining too much water or that can be turned into slush by insects bacteria or fungi and will smother the roots by creating areas that impede the flow of air.

In the case of the Encyclia alata in the photo, the orchid is growing in side of a wire basket that has a two-inch layer of pebbles inside.  As you can se the plant has been growing for a while in the basket, slowly increasing in size.   The younger pseudobulbs are not in contact with the media, they are about two inches over it.   The roots grow toward the basket and eventually enter the media.

On occasion I have used stones to hold the orchid in an empty pot.  In these cases, the plants are attached to a single stone and there is no media in the pot.   I do this with plants that produce larger, stronger root systems if the roots are allowed to grow with no media to confine them.  I used to grow Cattleya Jose Marty “Mother’s Favorite” in this way.    

Using stones as a potting media has the disadvantage that they are heavy.  The wire basket in which Enc alata is growing weights quite a bit.  However, the heavy weight has its benefits.  This Enc alata can produce a four feet tall inflorescence, with dozens of flowers.   The weight of the stones helps balance the weight of the inflorescence.

                Because stones don’t decay, you have to provide the plant with a balanced fertilizer.   During the growing season you have to really make sure this plant is fertilized regularly or the plant will produce smaller pseudobulbs that it could.   Stones are not water retentive, so the plant has to be watered often when during its active growth phase.

                Compared with the other media I use, stones are a very minor component of my orchid growing.  But they can be useful in particular cases for plants that have specific needs.    I prefer to use smooth river pebbles.    On one or two cases I have used them to cover fibrous potting material to stop birds from stealing it.

                A final note, don’t just grab any old stone and stick it in a pot.  I prefer to use volcanic rock because they tend to be chemically inert.  Some stones will react with the acids in the media and alter the pH of the mix, some plants like this, others don’t.  Never use stones that are crumbly or might leach unwanted chemicals into the mix.  

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.

A toadstool in the pot of Miltonia Earl Dunn

Early in the year, during the local dry season, I put a few pieces of very dry horse manure on top of the media of a Miltonia Earl Dunn.  I wondered if the addition of manure would have a positive influence on the growth of the plant.  When the rainy season arrived, the Miltonia started growing but the manure didn't seem to make any difference in its growth rate or the size of the pseudobulbs that were produced.  About two weeks ago tropical storm Bertha passed close to the island of Puerto Rico, it brought with it copious rain.  In two days 7.30 inches of rain accumulated, which is roughly about the same quantity of rain we would get in the months of June and July.  The heavy rainy spell stimulated many plants, Dendrobium crumenatum plants in bloom were everywhere in the island, my Dendrobium equitans plant is full of buds and Stanhopea panamensis developed two inflorescences.  But orchids were not the only ones to react to the increased humidity.

This morning I saw this delicate toadstool growing out of the pot of the Miltonia Earl Dunn.  The toadstool was very delicate, I am sure simply touching it would have damaged the cap.  The toadstool was in pristine condition during the morning before the day got hot.  Today was a singularly hot and dry day.  When I checked the toadstool it had become dehydrated and had collapsed.  My suspicious is that the addition of manure allowed this fungus to colonize the media of the Miltonia.  I occasionally find toadstools in the pots of other  orchids but usually they are quite small and inconspicuous.  This is the largest one I have ever seen.

The Miltonia doesn't show any sign that the fungus is harming it.  Given the warm, tropical conditions that are the norm in my garden, fungus are everywhere.   Even thought themedia has been colonized by this fungus, it doesn't look too decayed and the Miltonia roots seem healthy.

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.