Encyclia culture: Some notes on root initiation

One of the most important events in the seasonal cycle of Encyclia is root initiation. It At this time of the year, in early February I am expecting my plants to start growing their inflorescences. Most of my plants finished the growth of the new bulbs at the end of last year. A few, are doing their own thing. Encyclia Borincana started producing a new growth for an old, small pseudobulb, a newly brought Encyclia alata is showing new growth. A few roots with green tips can be seen here and there. This pseudobulb of Encyclia Renate Schimdt (Enc. Orchid Jungle x Enc. Alata) decided to produce a massive growth of roots. Locally, it is the start of the dry season, not a time I find desirable for a plant to increase its water needs to nurture root growth. But you got to do what the plant needs. Because I grow my orchids outdoors this mass of delicious, tender green tipped roots is a very tempting target for insects and other critters. To stop the roots from becoming food, I give the plant a spot application of a systemic insecticide. Systemic insecticides tend to concentrate on new growths, making then inedible to any insect that might be tempted to nibble on them. Protecting the roots at this stage is vital for the future survival of the plant. The loss of the root system of its newest pseudobulb can severely set back an orchid and might even endanger its survival. Note the length of the green part of the root. A very short green tip is not a good thing, it means the plant is not getting enough water. the lenght of the green in this orchid shows it is getting the right amount of watering to promote good root growth. Root initiation in many types of orchids is not like other plants, it can only happen a specific time of the year. So when it happens the plant has to be given the care it needs to produce a strong system of roots capable of sustain the next year growth, there will not be a second chance. On some instances a plant whose lead growth is damaged will produce a secondary growth a bit back in the stem, but that doesn’t always happens. Observing the long-term growth pattern of my Encyclia I have noted that they tend to rise slowly raise they stems away from the media. After a few years the pseudobulbs are sitting on a mass of roots a few inches tall, rather than directly on the media.

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.

Dendrophylax porrectus a leafless orchid growing on a camasey tree in the Rio Abajo forest

This orchid is native of Puerto Rico.  This orchid has no leaves just roots joined by a very short stem.  It produces tiny inconspicuous green flowers.  It can often be found growing on the branches of wild guava and camasey trees.

Dendrobium wardianum, culture notes

I had always been curious about Dendrobium wardianum but I had never had the opportunity to grow this plant because I could not find sources for it.  But in 2012 I found a source that would ship plants to Puerto Rico.  I ordered two plants.  When they arrived I found that they were tight;y wrapped in sphagnum moss against a flat piece of wood.  I never bury the stems of my plants in sphagnum moss, so I decided to remove one plant from the mount.  The other one I left untouched, just in case.

The plant I removed from the mount turned out to be three seedlings planted so close to each other as to appear to be parts of a single plant.  I carefully extricated their roots from the sphagnum.  It was clear they had not spent any appreciable time in the sphagnum as the roots came out easily.

The strongest seedling was given its own basket.  It had a nice fat, two inch cane.  I was very careful to keep the stem away from the media and to leave all the roots exposed.  I prefer to leave the roots of the Dendrobium seedlings and keikis exposed.  But the stem was close enough to the basket that the new roots would have to travel only a short distance to reach the media

The smaller, weaker seedlings were put in a basket together.  Note that the basket has a layer of medium sized bark, sphagnum moss and then another layer of medium bark.

A year after they were planted the seedling have grown in various ways.  The strongest seedling started growing in the spring and eventually produced a seven inch cane.  But it didn't pause for the year, instead it initiated another cane, this cane topped out at eighteen inches, a near adult cane.  The two smaller seedlings have grown much slower, one is still quite small.   I never watered these plants, they got all their water from rainfall.  They were fertilized but only when they were growing, the fertilizer was one high in nitrogen.  The other plant, the one I left in the sphagnum moss, rotted away completely, during the start of the rainy season. At first the leaves turned black and then pseudobulbs  also turned black and collapsed.

Here is the largest plant with its nearly mature eighteen inch cane.  It is still too early to determine if this plant will bloom under my climate conditions but is is clear it can grow well in my garden,  I will not subject this plant to a rest period until it has at least two full sized mature canes.  The two smaller plants will be moved to a sunnier location since they now have an established root system.  Hopefully this will help them grow larger and stronger.  If the larger plant produces another large cane in 2014, it will be given a rest period of decreased watering and more sun exposure.  Whether this will be enough to make it bloom, remains to be seen.

These are the approximate values for rainfall in my location in Rio Abajo

                             J       F      M       A       M       J       J       A       S      O      N      D

Rainfall (mm)       99   76     84     165     283    155   141   216    237   233  176  135

(inches)                3.9   3.0    3.3    6.5    11.1    6.1    5.5   8.5      9.3    9.1   6.9   5.3