Thursday, July 6, 2017

Dendrobium nobile culture: Growing naturalized in a tree in Aguadilla, Puerto Rico

I brought this plant back in 1990, at that time it was huge, it completely filled an twelve inch basket with its canes.  I got it from a plant vendor that had been growing the plant for years without it producing a single flower.  Although the plant was large, the vendor gave it to me very cheap.  The vendor was happy to clear bench space for more profitable plants and I was happy to have a plant to experiment what conditions would make it bloom.

In December, I took the plant with me to the place I lived at the time, at an altitude of of 3500 feet, in the Sierra de Luquillo, in the eastern part of the island of Puerto Rico.  The local temperature in winter can go down into the upper fifties and the local humidity is very high often in the nineties.  I put it in a place where it would get morning sunlight but would not get rained on.   Then I didn’t water it for two months.  Because of the high humidity the canes didn’t get very shriveled and wrinkly.   In March of that year I started watering it sparingly, in April I started watering it normally but didn’t give it any fertilizer.

In May of that year the plant was covered with buds.  When it bloomed, it produced 150 large, fragrant flowers.  It was quite a spectacle.    When the plant finished blooming I took it out of the basket and divided it in many pieces.   I gave away several the pieces, potted some, put some in baskets and tied a piece to the trunk of an avocado tree.

The plant in the avocado tree grew slowly.  Mainly because I left it completely alone, no watering or fertilizer.  It has been in the tree now for three decades.  At first it was in deep shade, and it would not bloom even when the canes were fully adult sized.  Then part of the tree was cut down and the plant suffered sunburn, it bloomed weakly.  Now that it gets full sun in the morning and dappled sunlight the rest of the day it is blooming better than ever.  The canes are the largest it has ever produced, some are two and a half feet long.

The flowers are fewer and larger than the plants that are potted and get watered and fertilized.  The color of the flowers is variable.  I have observed that the plants that are in full sun have flowers with more intense color.

This plant has a very wide temperature tolerance and can even endure temperatures close to freezing without harm.   From my experience, I can attest that it is a good plant to naturalize on trees on those areas that are not subject to freezing weather.  Although I have some plants on pots and on baskets, none is as large or as healthy as the plant naturalized on the tree.  This is mainly because they must be repotted from time to time and this means they lose some of their root ball.  The naturalized plant has a massive number of roots that cover the trunk for a few feet around it in all directions. 

However, this plant might not bloom even with the best of care, this can be caused by a number of reasons.  First, if grown in a spot that is too shady the plant will not bloom, it will produce long and spindly weak canes.   If given fertilizer at a time when it is finishing its growing and getting ready for the dry season this will stimulate it to start new growths and can short circuit the blooming season.   If watered at the time when it is normally the dry season in its habitat, this also can inhibit blooming.  Some plants can bloom in the shade, even if fertilized and watered, but often they produce just a few flowers near the tip of the canes.  Low temperatures stimulate blooming in this species.  The plant canes can lose their leaves during the dry season, this is normal and a prelude to blooming.  I should add that I have seen fully leafed canes blooming.  But generally, it has been my experience that plants that keep their leaves bloom less abundantly than those that become deciduous.

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