The Orchid Garden

Dendrobiums not blooming

Question:

Thank you! More info: ! have about 10 different plants. Several are Phal-type, I have a Burana Green, Banana Royal, etc. I also have a D. kingianum ‘Sweet.’ Then there are several nobile types – all from kikis I received with winning bids at the CT Orchid Society auction in June. The BG, BR were blooming when I bought them. They have put up 2 new growth each, new growths seem to be about the same size as the old. Leaves are medium green – not a dark dark green but not the pale light green that I see sometimes. The kingianum has put up 2 batches of new growth – one in the summer and one in about November after a few weeks under the new 250wt Metal Halide light. All the new growth is a bit bigger than the old, looks very happy. The plant may have been confused into thinking that there was a new summer because of coming inside for relative darkness for a few weeks, then suddently a new and bright light. It has never bloomed for me. All seem to be growing pretty well. Leaves are shiny, p-bulbs shiny, not wrinkled, roots are healthy, white, a few on the medium surface with the nice green tips. I am still new to orchid growing, relative to my 25+ years growing wildflowers, etc. We definitely do not have much difference between night and day temps in this house in the winter – we have a small and active toddler so we keep it fairly even – about 64 F. As soon as it gets a bit warmer I can put things out on the porch – which quickly gets to about 60 in the sun, has plastic on 3 sides. That will give the night-drop. Thanks for any comments! Val

Hi Val, Do any of these Dendrobs have names you can supply?  In my opinion, all orchids need a drop in night temp to do well.  There might be a few where it is not nec. but I don’t know of them. Have they bloomed for you before, are the growths as big or bigger than the old growths, did they go through a dormant period or just keep on growing, are the leaves a deep dark green or a light green.  I am not a dendrobium person but I think there are quite a few here who can answer question with a little more info. Stephen

The question concerns the culture of a hodge podge of dendrobiums. I would be glad to offer a culture guide to specific types, if desired, but will post a few comments which I believe offer a general guide to all of the dendrobiums-this is from the British. Most orchid growers are aware of the large number of species in the genus dendrobium, and the diverse cultural requirements for their management. Likewise, in reading books on their classification one is soon overwhelmed. I  believe this represents the easiest way to classify  this group, and in particular have a reasonable understanding of the cultural requirements for any specific species. Dendrobiums has led us to understand the difficulties many newcomers have in learning how to tackle their  culture. Reading the Willis Dair lists suggests to us that these  difficulties extend to both sides of the Atlantic. Although Dendrobiums occur naturally only in a well defined geographical area – from India to Australia – there is within this area a very big range  of climatic and environmental variation. Understanding this geography  is an important part of understanding the necessary conditions for  successful growing. A good atlas, or better still a good globe can be  as valuable as a textbook!  We have put together the following notes  for the British Orchid Growers Association "Growers and Buyers Guide, 1996-97" and offer them as possible assistance to those tackling their  first plants of this fascinating and important genus.         Dendrobiums come from South East Asia in an area that  stretches from Northern India to the islands off the East coast of New  Guinea and Australia , and to Polynesia.  The latitude where they grow  is important. The Equator runs through the middle of the territory,  and here it is always hot at sea level witout any seasonal  variation. However the plants from north of the Tropic of Cancer and  south of the Tropic of Capricorn are used to a much greater range of  climate, with colder drier winters and warmer wet summers. It is  important therefore to know where every plant comes from.         For convenience we consider cultural advice under three headings, 1. Nobile (pronounced no-bill-ay) type, or Himalayan plants.  2. New Guinea plants . 3. Australian plants.  1. Nobile Dendrobiums  These are some of the easiest to grow, but can be a little difficult to bloom  regularly. Their flowers are showy with colours ranging from white through  pink to purple, and the lip is often beautifully marked  in contrasting colours. They make magnificent specimen plants. Others are yellow or brown, while the recently introduced Yamamoto hybrids have all the colours of the  rainbow. The Himalayan climate is not unlike a warmer Switzerland, with  bright, cold but dry winters.         Culture. November to February: day time temperatures can drop  to 40-45F, during this time you should not water or feed, but provide  plenty of light and air movement. March to May or June, warmer and  moister conditions; buds and flowers develop and new growths  appear. Water sparingly until the new growths have developed good roots. June to November corresponds to the Monsoon period, warm and  very wet. Give a low strength, high nitrogen feed in April and May,  then feed weekly with a balanced fertilizer during maximum  growth. Change to high potash for the last month, October. Note – if  you do not dry and cool the plants during winter you won’t get  flowers! Himalayan Dendrobiums from lower altitudes need a less harsh winter, but still dry.         2. New Guinea Dendrobiums . The climate varies with altitude and in the mountainous areas there are cool, wet misty  nights and mornings followed by warmer bright days. The exquisite  cool and intermediate miniatures like D. cuthbertsonii grow here. Never allow  them to dry out completely, and feed often with dilute fertilizer. The river valleys between the mountain ranges are warmer and wetter, and home to some of the most exotic of New Guinea orchids, e.g. D. lasianthera from the Sepik River basin, and many latouria types with long lasting flowers. All these need generous feeding and watering. The southern plains resemble Queensland, Australia, but are wetter and very warm all year through. There is seasonal rainfall variation with a wetter summer and drier winter. Two of the outstanding species from this area, (which are also found in Queensland ) are D. bigibbum (D. phalaenopsis) and D. canaliculatum, the former often found growing on rocks, the latter on the trunks of paperbark trees. The easiest New Guinea plants for beginners are D. aberrans (cool conditions); D. lawesii or D. antennatum (intermediate), and D. atroviolaceum or D. bigibbum (warm).   3. Australian Dendrobiums D. kingianum and near relatives are the easiest to grow. The pseudobulbs or  canes can be any length from 5-30cm tall, and are thin and often spindly and  tough. The leaves are narrowly oval, with two to four at the top of each cane.  The flowers appear in late winter or early spring in loose sprays at the tops of both old and new canes. New plantlets or keikis may sometimes appear  instead. These can be removed and potted separately after they have developed  good roots or left on the parent plant where they will eventually flower  also. There are two to ten flowers on a spray, each measuring 1-3cm across in shades of pink or purple. Other plants in this group may be taller and have  cream or white flowers. For their culture give intermediate temperatures and  drier conditions than other Dendrobiums. Spray once a week, and water  generously in the spring and autumn with dilute feed. A few cold weeks, down  to 45F, will encourage flowering.   Potting – Dendrobiums like to be in small pots with their roots confined. Bark, perlag  and charcoal make up an open mix which drains easily. Repot either when the compost becomes acid and soggy, or when the pot is full of roots. This often  means every year. Plants from the mountainss of New Guinea like a little  mosss mixed with the bark, or they can be grown on slabs of bark or treefern  on a mossy bed. Such slabs need daily misting for most of the year.   Dendrobium hybrids. These are almost always derived from species within one group, either  Himalayan, New Guinea or Australian. Surprisingly, most of the ‘Singapore’ orchids, although developed there, are derived from species of New Guinea and  the adjacent islands, and need much the same culture as the River Valley New  Guinea species. So – when you buy a Dendrobium, ask which group it belongs to, and where it comes from – and we don’t mean which nursery!  From Richard and Ann

Response:

Thanks so very much for the info.  I, for one, appreciate this info on Dendrobiums.  Concise and to the point. Stephen

– Hide quoted text — Show quoted text – Thank you! More info: ! have about 10 different plants. Several are Phal-type, I have a Burana Green, Banana Royal, etc. I also have a D. kingianum ‘Sweet.’ Then there are several nobile types – all from kikis I received with winning bids at the CT Orchid Society auction in June. The BG, BR were blooming when I bought them. They have put up 2 new growth each, new growths seem to be about the same size as the old. Leaves are medium green – not a dark dark green but not the pale light green that I see sometimes. The kingianum has put up 2 batches of new growth – one in the summer and one in about November after a few weeks under the new 250wt Metal Halide light. All the new growth is a bit bigger than the old, looks very happy. The plant may have been confused into thinking that there was a new summer because of coming inside for relative darkness for a few weeks, then suddently a new and bright light. It has never bloomed for me. All seem to be growing pretty well. Leaves are shiny, p-bulbs shiny, not wrinkled, roots are healthy, white, a few on the medium surface with the nice green tips. I am still new to orchid growing, relative to my 25+ years growing wildflowers, etc. We definitely do not have much difference between night and day temps in this house in the winter – we have a small and active toddler so we keep it fairly even – about 64 F. As soon as it gets a bit warmer I can put things out on the porch – which quickly gets to about 60 in the sun, has plastic on 3 sides. That will give the night-drop. Thanks for any comments! Val Hi Val, Do any of these Dendrobs have names you can supply?  In my opinion, all orchids need a drop in night temp to do well.  There might be a few where it is not nec. but I don’t know of them. Have they bloomed for you before, are the growths as big or bigger than the old growths, did they go through a dormant period or just keep on growing, are the leaves a deep dark green or a light green.  I am not a dendrobium person but I think there are quite a few here who can answer question with a little more info. Stephen The question concerns the culture of a hodge podge of dendrobiums. I would be glad to offer a culture guide to specific types, if desired, but will post a few comments which I believe offer a general guide to all of the dendrobiums-this is from the British. Most orchid growers are aware of the large number of species in the genus dendrobium, and the diverse cultural requirements for their management. Likewise, in reading books on their classification one is soon overwhelmed. I  believe this represents the easiest way to classify  this group, and in particular have a reasonable understanding of the cultural requirements for any specific species. Dendrobiums has led us to understand the difficulties many newcomers have in learning how to tackle their  culture. Reading the Willis Dair lists suggests to us that these  difficulties extend to both sides of the Atlantic. Although Dendrobiums occur naturally only in a well defined geographical area – from India to Australia – there is within this area a very big range  of climatic and environmental variation. Understanding this geography  is an important part of understanding the necessary conditions for  successful growing. A good atlas, or better still a good globe can be  as valuable as a textbook!  We have put together the following notes  for the British Orchid Growers Association "Growers and Buyers Guide, 1996-97" and offer them as possible assistance to those tackling their  first plants of this fascinating and important genus.     Dendrobiums come from South East Asia in an area that  stretches from Northern India to the islands off the East coast of New  Guinea and Australia , and to Polynesia.  The latitude where they grow  is important. The Equator runs through the middle of the territory,  and here it is always hot at sea level witout any seasonal  variation. However the plants from north of the Tropic of Cancer and  south of the Tropic of Capricorn are used to a much greater range of  climate, with colder drier winters and warmer wet summers. It is important therefore to know where every plant comes from.         For convenience we consider cultural advice under three headings, 1. Nobile (pronounced no-bill-ay) type, or Himalayan plants.  2. New Guinea plants . 3. Australian plants.  1. Nobile Dendrobiums  These are some of the easiest to grow, but can be a little difficult to bloom  regularly. Their flowers are showy with colours ranging from white through  pink to purple, and the lip is often beautifully marked  in contrasting colours. They make magnificent specimen plants. Others are yellow or brown, while the recently introduced Yamamoto hybrids have all the colours of the  rainbow. The Himalayan climate is not unlike a warmer Switzerland, with  bright, cold but dry winters.         Culture. November to February: day time temperatures can drop  to 40-45F, during this time you should not water or feed, but provide  plenty of light and air movement. March to May or June, warmer and  moister conditions; buds and flowers develop and new growths  appear. Water sparingly until the new growths have developed good roots. June to November corresponds to the Monsoon period, warm and  very wet. Give a low strength, high nitrogen feed in April and May,  then feed weekly with a balanced fertilizer during maximum  growth. Change to high potash for the last month, October. Note – if  you do not dry and cool the plants during winter you won’t get  flowers! Himalayan Dendrobiums from lower altitudes need a less harsh winter, but still dry.         2. New Guinea Dendrobiums . The climate varies with altitude and in the mountainous areas there are cool, wet misty  nights and mornings followed by warmer bright days. The exquisite cool and intermediate miniatures like D. cuthbertsonii grow here. Never allow them to dry out completely, and feed often with dilute fertilizer. The river valleys between the mountain ranges are warmer and wetter, and home to some of the most exotic of New Guinea orchids, e.g. D. lasianthera from the Sepik River basin, and many latouria types with long lasting flowers. All these need generous feeding and watering. The southern plains resemble Queensland, Australia, but are wetter and very warm all year through. There is seasonal rainfall variation with a wetter summer and drier winter. Two of the outstanding species from this area, (which are also found in Queensland ) are D. bigibbum (D. phalaenopsis) and D. canaliculatum, the former often found growing on rocks, the latter on the trunks of paperbark trees. The easiest New Guinea plants for beginners are D. aberrans (cool conditions); D. lawesii or D. antennatum (intermediate), and D. atroviolaceum or D. bigibbum (warm). 3. Australian Dendrobiums D. kingianum and near relatives are the easiest to grow. The pseudobulbs or  canes can be any length from 5-30cm tall, and are thin and often spindly and  tough. The leaves are narrowly oval, with two to four at the top of each cane.  The flowers appear in late winter or early spring in loose sprays at the tops of both old and new canes. New plantlets or keikis may sometimes appear  instead. These can be removed and potted separately after they have developed  good roots or left on the parent plant where they will eventually flower  also. There are two to ten flowers on a spray, each measuring 1-3cm across in shades of pink or purple. Other plants in this group may be taller and have  cream or white flowers. For their culture give intermediate temperatures and  drier conditions than other Dendrobiums. Spray once a week, and water  generously in the spring and autumn with dilute feed. A few cold weeks, down  to 45F, will encourage flowering.   Potting – Dendrobiums like to be in small pots with their roots confined. Bark, perlag  and charcoal make up an open mix which drains easily. Repot either when the compost becomes acid and soggy, or when the pot is full of roots. This often  means every year. Plants from the mountainss of New Guinea like a little  mosss mixed with the bark, or they can be grown on slabs of bark or treefern  on a mossy bed. Such slabs need daily misting for most of the year.   Dendrobium hybrids. These are almost always derived from species within one group, either  Himalayan, New Guinea or Australian. Surprisingly, most of the ‘Singapore’ orchids, although developed there, are derived from species of New Guinea and  the adjacent islands, and need much the same culture as the River Valley New  Guinea species. So – when you buy a Dendrobium, ask which group it belongs to, and where it comes from – and we don’t mean which nursery!  From Richard and Ann

Response:

Thank you! More info: ! have about 10 different plants. Several are Phal-type, I have a Burana Green, Banana Royal, etc. I also have a D. kingianum ‘Sweet.’ Then there are several nobile types – all from kikis I received with winning bids at the CT Orchid Society auction in June. The BG, BR were blooming when I bought them. They have put up 2 new growth each, new growths seem to be about the same size as the old. Leaves are medium green – not a dark dark green but not the pale light green that I see sometimes. The kingianum has put up 2 batches of new growth – one in the summer and one in about November after a few weeks under the new 250wt Metal Halide light. All the new growth is a bit bigger than the old, looks very happy. The plant may have been confused into thinking that there was a new summer because of coming inside for relative darkness for a few weeks, then suddently a new and bright light. It has never bloomed for me. All seem to be growing pretty well. Leaves are shiny, p-bulbs shiny, not wrinkled, roots are healthy, white, a few on the medium surface with the nice green tips. I am still new to orchid growing, relative to my 25+ years growing wildflowers, etc. We definitely do not have much difference between night and day temps in this house in the winter – we have a small and active toddler so we keep it fairly even – about 64 F. As soon as it gets a bit warmer I can put things out on the porch – which quickly gets to about 60 in the sun, has plastic on 3 sides. That will give the night-drop. Thanks for any comments! Val

– Hide quoted text — Show quoted text – Hi Val, Do any of these Dendrobs have names you can supply?  In my opinion, all orchids need a drop in night temp to do well.  There might be a few where it is not nec. but I don’t know of them. Have they bloomed for you before, are the growths as big or bigger than the old growths, did they go through a dormant period or just keep on growing, are the leaves a deep dark green or a light green.  I am not a dendrobium person but I think there are quite a few here who can answer question with a little more info. Stephen Do these need a drop in temperature at night to initiate blooming? Plants look healthy, nice roots, new growth came up big and fat, nice shiny leaves. I grow in my dining room – under lights, partly windowsill. House is consistently 64 degrees, day and night temp.

Response:

Hi Val, Do any of these Dendrobs have names you can supply?  In my opinion, all orchids need a drop in night temp to do well.  There might be a few where it is not nec. but I don’t know of them. Have they bloomed for you before, are the growths as big or bigger than the old growths, did they go through a dormant period or just keep on growing, are the leaves a deep dark green or a light green.  I am not a dendrobium person but I think there are quite a few here who can answer question with a little more info. Stephen

– Hide quoted text — Show quoted text – Do these need a drop in temperature at night to initiate blooming? Plants look healthy, nice roots, new growth came up big and fat, nice shiny leaves. I grow in my dining room – under lights, partly windowsill. House is consistently 64 degrees, day and night temp.

Response:

Do these need a drop in temperature at night to initiate blooming? Plants look healthy, nice roots, new growth came up big and fat, nice shiny leaves. I grow in my dining room – under lights, partly windowsill. House is consistently 64 degrees, day and night temp.

Response:

Filed under: Dendrobium Orchid

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