Tuberous Tropical Terrestrials!!!   Leave a comment

It is the time of year again when the Habernarias from Asia are blooming.  The majority of these plants are small, non-descript, and easily overlooked.  Even when in bloom, the flowers can be small and green, and uniformly described as “uninteresting.”  But a true gardener loves a challenge, and loves the unique, and I have fallen in love with this group of plants.  They are unique in many ways, but the most obvious one is that they lose their leaves and remain dormant for a large part of the year.  Yes, just like tulips or daffodils, these plants are deciduous!

Growing the tropical Habernaria relatives can be difficult, but mostly because orchid growers are unaccustomed to growing deciduous plants.  Being tropical, these species do not become dormant because of low temperatures or decreased light levels, as those deciduous orchid in higher latitudes.  Instead, they depend on the moisture content of the soil to determine when to grow and when to rest.  As such, keeping these tubers dry during the winter rest is extremely important.  Keep them too wet, and they rot.  On the other hand, they cannot be kept in extremely dry conditions, or the tubers will completely dessicate.  Some growers remove the bulbs from their pots and store them over the winter.  While this works for them, it doesn’t for me, and I lost a few prized Habernaria last year using this method.  Instead, I just keep them in their pots, and move the pots to a dry place.  I water them sparingly, just enought to keep the soil from completely drying out.  One method that hs worked well for me in the past is keeping a thin layer of sphagnum on top of the soil, and watering just enought to mositen the moss, but not the soil underneath.  Whichever method you choose, the key is to keep the humidity levels in a range high enough to prevent total drying while low enought to discourage rotting.  I suspect (though have not tested this theory) that a relative humidity of 30-40% is ideal.  he mix you grow these in should drain well, and be high in humus.  Traditional peat-based potting soils can hold too much water if packed too tightly into the pot, so adding perlite, charcoal, or coarse sand is advisable.  I feel that these plants should be fertilized rather heavily during their growth, not so much for the vegetation and flowers that the plant is producing (the nutrition from these is derived from last years tuber) but because the plant is storing energey in its tuber for next year.  Geeting your plants to produce new growths is especially dependant on adequate fertilizing.  I do think that some organinc fertilizers may be beneficial for these plants, particularly bone meal, as it provides higher levels of phosphorous and phosphorous is stored extensively by deciduous, tuberous or bulbous plants in their storage organs.  When I notice green shoots, I start to water.  Just a little at first, but then I aim for constant moisture.  One must still guard against water in the axils, as this will lead to rotting of the blooming spike, and maybe the entire growth.  At some time after blooming, the leaves will strt to yellow and die.  Decrease watering until the soil is almost dry, and wait for the cycle to start again!


Posted September 22, 2011 by brianmonk in Orchids

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