Thursday, February 17, 2011

Dendrobium anosmum and its relatives, the rest period as a tool to promote abundant blooming


Dendrobium primulinum stems at the tail end of the growing season

The same plant as above after two months of no water or fertilizer and exposure
to bright light.
Dendrobium Adrastra blooming from leaveless canes

A properly rested plant of Den, anosmum with more than forty buds in a single cane.  Note the blooms are produced all along the lenght of the stem and not just near the tip
A relatively young Den. primulinum plant, note that stems are plump and still have the remains of a few leaves.  See below the plant in full bloom.


Giving your Dendrobium a rest period can be the difference between an impressive and abundant floral display and one that produces just a few blooms.  Species of Dendrobium of the group that includes  anosmun, primulinum, cucullatum, nobile and parishii among others flower best when given a rest period that mimics the seasonal conditions that are the trigger for blooming in their native haunts.
What is the nature of the seasonal rest period in this particular group of orchids?  These Dendrobium live in the south east of Asia and in parts of India.  In these regions they are subjected to the monsoon weather system.  In the summer there is abundant rains that fuel the growth of their long pendent canes.  But as winter approaches the rain diminishes considerably and eventually ceases for some months.  The constant cloudiness of the monsoon season is then substituted by clear sunny skies.   As the rain ceases the trees lose their leaves and the Dendrobium are exposed to high levels of sunlight.  Finally as the dry season starts the Dendrobium lose their leaves and enter the dry season as a bundle of stems that not in the least resemble their lush rainy season appearance.
Generally, but not in every geographical region, the dry season is also a season of lower temperatures.  The combination of high light conditions, drought and low temperatures is said to prime the buds of the stem of many Dendrobium for flowering. That means that the seasonal change is the cue that makes the vegetative buds that are all along the stems turn into flower buds.   When orchidists talk about giving their plants a rest period they are referring to the set of circumstances in the natural habitat of the Dendrobium that I have outlined in the preceding paragraphs.
Personally I stop all fertilizing and watering in November.  This means that the media of some of my plants will become bone dry and stay that way sometimes for several weeks.  All my pendent Dendrobium tolerate these lengthy dry spells with little complain, probably because even thought they are not getting any water the environmental humidity is high enough to prevent severe shriveling of the canes.  However I do have to confess that if I see a plant becoming excessively wrinkled from desiccation I do water it lightly.
 Although these conditions might seem severe and some of these pendent Dendrobium will flower quite well without experiencing the most severe rigors of the rest season other species will not produce flowers if not given a distinct rest period.  The best example of an orchid of this group that grows very well and yet blooms poor in the tropics is Dendrobium nobile.  If maintained under constant warm conditions, fertilized all year and kept under shady conditions most nobile will bloom poorly and may not bloom at all.  
Some orchidist just can’t resist the urge to water and give fertilizer to their plants year round. These orchidists generally have a tough time getting blooms out of them.  I have seen massive nobile specimens that have never produced a single flower.  I once brought a large plant for the ridiculous amount of $15.00 because the garden store owner had become tired of waiting for it to bloom and felt the plant was taking too much space and not bringing any profit.   I gave this plant a proper rest period and the plant responded by producing 150 large and fragrant flowers in about twenty canes.  All those canes that had accumulated without blooming for years produced flowers all at the same time.
I know some people keep watering their plants even in the rest period and that some of those plants bloom from canes that have kept their leaves.  But so far I have not seen a plant that has kept its leaves bloom as abundantly as one that has lost all its leaves due to the stress of the rest period.

35 comments:

seroggenka said...

Hello Ricardo Valentin!
I'm from Russia, sorry for the very poor English (I use a translator Google) and I doubt whether you understand me, but I can not ask a question now for me the most current, relatively dormant period Dendrobium anosmum.
My Den. anosmum alba x pink-Species younger finished flowering plant, on January 1 of 2011 ceased to irrigate, fertilize, put in a room with high humidity and with good lighting, temperature, day / night on average +14 / +9 ° C to date has never watered. Tubiridii dropped all the leaves on the nodes are felt seal but flower buds have not yet sprouted, there are two new germ and the average daily temperature rose to 20 - 25 ° C.
Please tell me you can already begin watering or must wait until the stems???

Thank you!!!

seroggenka@rambler.ru

Ricardo in PR said...

I start watering when the flowering buds on the cane start swelling. Some people start watering the plants as soon as the new vegetative growths that will produce the canes start growing from the base of the plant. Locally it doesn't seem to make much difference which one of these two events you use to determine when to start watering, the plants bloom well either way.

seroggenka said...

Many thanks for the advice!
Hope blooms:)

Anonymous said...

hi can i have your email pls ? i have some few question for you to answer about dendrobium anosmum :)

Ricardo in PR said...

You can post the questions here where the answers will help everybody. I don't post my email here because my box would become swamped.

Anonymous said...

will pendent dendrobium canes that have dropped their leaves and flowered ever bloom again? If not, will these canes be good candidates for propagation? Thank you.

Ricardo in PR said...

Generally canes of pendent Dendrobium that have bloomed will never produce flowers again from those buds that were spent flowering. However ocassionally older canes will produce a few flowers from buds that remained latent when that particular cane bloomed. Older canes can be used to propagate the plant as long as the plant is left with tow or three mature canes. Cutting the canes as soon as they have finished blooming to use them for propagation is not adviceable as this weakens the plant. It is very common to see plants of the white variant of anosmum in a truly pitiful state due to ruthless cutting of their older canes for propagation. Because they don't have older canes to help the plant achieve the full size in the new growth, plants that have been stripped of their older canes often have small scrawny canes that bloom in a mediocre fashion.

Anonymous said...

Thank you for your comments about spent canes. I currently have what I believe to be hono hono plants that I brought back from Hawaii to my home in coastal Virginia in 2008. The plants have always remained small and never bloomed until this year. Two of the canes grew so well this past summer and now have a few flower buds on them. Can you direct me to your method of growing this type of orchid? I know I cannot achieve what you have in your tropical climate but I would like advice as to what I can do during the short period of warmth and humidity from June through October in my location to achieve the best that I can. They are currently living on a window shelf in my laundry room. Thank you again!

Ricardo in PR said...

This link will take you to an article where I detail how I grow these plants. http://ricardogupi.blogspot.com/2008/10/dendrobium-anosmum-when-cultured-so.html
Hopefully you will be able to use some of these recommendations for your particular situation.

Wanda Zook said...

Ricardo, I used to have that orchid when I lived in PR. Do you know if it grows well in FLorida?

Anonymous said...

Ricardo, what is the lowest temperature these dendrobiums can take during their winter rest. I am in central, coastl Florida. We can have winter weather down into the 40s F. At what temperature should I bring these resting dendrobiums inside?

Ricardo in PR said...

It all depends on the species. Dendrobium lodiggesii and Dendrobium nobile will take temperatures down into the forties with no ill effects. In general Dendrobium that hail from the foothills of the Himalayas can take cooler temperatures that the ones that come from more coastal locales. Personally I think a few nights of temperatures in the high forties will hardly make any impression in most deciduous Dendrobium if they are kept dry. In fact it may make the cooler growing species bloom better. Locally temperatures only go down to the middle fifties and that for a few nights a year in the depths of winter, so I can't speak from my own experience. The book I use to check the lowerst temperatures a particular species will take is Dendrobium by Baker and Baker.

Claudia said...

Hola Ricardo !!! Me encantas los dendrobiums y los cultivo bastante bien, tienes alguna lista de todos aquellos que necesitan descanso????

Ricardo in PR said...

Las especies que tengo que florecen mejor después de un periodo de temperaturas mas bajas y una reducción en el regado son; anosmum, aphyllum, densiflorum, devonianum, farmeri, harveyanum, loddigesii, lyndleyi nobile, parishii y primulinum. Sus híbridos tambien se benefician de un periodo de descanso, Adrastra, Bohemian Rhapsody, densiflorum x farmeri y Adrasta x parishii. En general aquellos Dendrobium que vienen de bosques que experimentan climas de monson, en el norte de la India y los de las partes altas de los países del sur de Asia florecen mejor después de un periodo de descanso.

Claire A. said...

Hello Ricardo,
I assume that keikis need to be watered year round until they grow to a certain size; is that a correct assumption? Do the canes have to reach a certain length before you start subjecting the plant to a rest period from water? Thanks.

Ricardo in PR said...

Keikis have to be treated differently from adult plants. Generally small keikis are watered year round and not allowed to endure a rest period. Once they have at least one cane that is close to the size of an adult cane, they are then treated the same as the adult plants.

Claire A. said...

Thank you for your reply about watering keikis. I don't know if you ever posted about how you make your pots from soda pop bottles, but I have some questions about that. How large a hole do you make at the bottom? I made the bottom hole large enough to put the roots through but maybe the hole was too big. I could not figure out how to keep the plant and potting media from falling out of the bottom. One of your pictures showed shade cloth covering the bottom, but how do you keep the shade cloth from falling through the hole? Thank you.

Ricardo in PR said...

When I put a plant in a pot made of a soda pop bottle what I do to keep the media in depends on the size of the root ball. If the root ball is huge and fills the bottom completely I simply make two small holes about an inch from the bottom end of the pot, on opposite sides of the pot, and then I use them to tie the plant to the pot. A piece of wire usually suffices for smaller plants. For larger plants I make four holes at 90 degrees of each other all around the bottom. With plants with small or deteriorated root balls I put a piece of wire netting on the bottom of the pot and tie the base of the plant to the wire. In these cases I cut the bottom of the pot from the part where the neck of the bottle starts to get narrow. This makes for a smaller hole but it provides and edge to place the wire against. The weight of the media keeps the wire firmly in place.

Hil @ Hilli322@gmail.com said...

Hello Richard! I've been following your blog for a while and now I've finally built the courage to post a question. I am in love with the deciduous, hanging dendrobiums. When I try to find the one In particular comes up as d. Aphyllum but it's not the one. It has brownish-red stalks instead of the greenish-grey. The stalks might even have hairs or fuzz on them. Do you think you can point me in the right direction as to the proper label. Thank you much in advance!

Ricardo in PR said...

Dendrobium aphyllum aka as pieradii and as cucullatum never has hairs on the stems. At least none of my clones is in the least hairy. These plants are commonly available under the name Den. cucullatum or Den. pieradii. I have three clones of this plant and although the flowers are the same color, they are variable in size as are the plants. My smaller clone produces canes that barely top two feet long. It produces a few small flowers near the tip of the stem. Another clone I have is slighly bigger and produces flowers with are smaller that those of the smaller plant. Lastly my third clone can reach six feet long and produces dozens of flowers in a single cane. The lips are wider that those of the other two clones. But this large plant, doesn't grow large unless given extremely good care, under standard care it hardly grows larger that the previous clones and most people are unaware of its potential. Unfortunately if you buy in the internet it is impossible to know the potential of the plant you are buying. There are several species vendors that carry this plant. Sometimes good plants can be found on ebay.

Hil said...

Thank you for your prompt response and explanation. I've been buried with work up to my nose so my apologies for the delay. I bought a D. Aphyllum (or as they labeled it pierardii or cucallatum). I actually just received it today 04.24.13 and boy am I excited. The one I have in fact has the greenish-grey stalks, if I could provide you with a photo of the one I've seen (but unable to label I would love too...). I noticed that you're on the orchid source, would that be a proper place to post a photo? Please note, I'm not a crazed stalker of any sort. Just recognized you and a few others in similar forums.

Ricardo in PR said...

Yes, by all means post it in the orchid source forummso I can see the plant. I won't feel stalked, its not like I am a celebrity or anything. In fact, if I were ever cyberstalked I would never stop talking about it to friends and family!

Hil said...

Cool, it's on it's way! :)
Btw, you are great at responding quickly!!

Anonymous said...

hi ricardo

jane said...

hi ricardo i have a few questions about den anosum.my growing cond are under t5 grow light under bright light 12 hrs a day no water or fertilizer since nov 1st encept for one watering due to dry canes now there are 2 new canes at base of the plant but i dont see buds forming yet tems are daytime74-78 night temp 55-66.at what point shoud i begin water and fertilizer if buds dont develop?will buds still develop now with the 2 new canes forming or is it to late.thanks

Ricardo Valentin said...

If it is pure anosmum, an not one of the parishii/rhodopterigium hybrids that infest the market, it may not bloom if the canes are less than two feet long. Some of my anosmum start blooming when the cane surpasses three feet long. Another issue might be the lack of seasonality in the light schedule, this orchid shows its buds around February, when the days are becoming noticeably longer. My plants only experience night temperatures of under sixty for a very brief period each year, so I cannot say if that will inhibit blooming.

Ricardo Valentin said...

I start watering and fertilizing when the growing buds are about two inches long, My plants have growing flower buds at this time so I like to give them plenty of water. Some plants can have sixty flowers so you dont want them to lack water.

jane said...

thanks for your advice! since i wrote you i think i may feel some small bumps on the canes by the nodes.hopefully they are the buds beginning to form and not my wishful thinking. thanks again.

Ricardo Valentin said...

If the little bumps are on the opposite side of the place where there was a leaf in the cane, they are almost surely developing flower buds.

Diane Prince said...

Richardo,

Would you please advise me if Dendrobium Green Lantern (Dawn Maree x cruentum would need this required rest period to promote blooms. I have had Green Lantern for a year and still not sure if this rest period is required after searching the internet.

Thank you,
diane@realbits.com

Ricardo Valentin said...

I had Dendrobium Dawn Maree and it didn't need a rest period to bloom. In fact it was healthier if watered regularly. My impression is that the intensity of light the plant gets, day lenght and plant size are more important factors in blooming Dawn Maree and its hybrids than a rest period.

Anonymous said...

Hi Ricardo im just an 11 year old boy in quezon city,philippines and my grandmother gave me a dendrobium anosmum,locally we call it sanggumay.I was wondering how i should treat it.I know how to take care of larger ones but its a 2-3 foot tall plant should i encourage it to produce more vegetative growth first or should i already let it flower its extremely hot here in quezon city,philippines with evening temperatures reaching 30ºc.Ther is always relatively high humidity never getting lower than 40.Im planning to mount it on a talang branch with some moss.The plant has plenty of keikies but i dont want to remove them because of the plants small size i have built my own orchid garden by saving some of my school allowance.
Any advice will be appreciated.

Ricardo Valentin said...

Your locality seems like a place where Dendrobium anosmum would grow well with just basic care. Your plant to tie the orchid to the trunk sounds good. My advice would be that if you can get orchid fertilizer, the kind you dissolve in water and its either blue or green, that would greatly help the plant achieve adult size quickly if given every week during the growth phase. Any kind would be good, I have used 20-20-20 with no problems for years. Sometimes when I am tying anosmum to a tree, I use a piece of dry coconut husk instead of moss, there are so many coconuts where I live that I can get all the pieces I want for free.

gawayn coronel said...

Thank you for the help Ricardo,my country,from my experience is the kind of place that when you're outside there is always at least 1 coconut tree.Can diluted liquid fertilizer that is 5-4-4 be enough.it is extremely hot on this month where i come from and it recently reached 35.7ºc.They are getting a few hours of direct sun in the morning and then get direct sun slightly filtered by a net from 11-1:45 then tree blocked by neem and chime trees until 3:30 then gets bright shade the rest of the day.there are orange streetlights brightly shining about 20 feet from my plants,will this affect flowering.

gawayn coronel said...

Thank you for the help Ricardo,my country,from my experience is the kind of place that when you're outside there is always at least 1 coconut tree.Can diluted liquid fertilizer that is 5-4-4 be enough.it is extremely hot on this month where i come from and it recently reached 35.7ºc.They are getting a few hours of direct sun in the morning and then get direct sun slightly filtered by a net from 11-1:45 then tree blocked by neem and chime trees until 3:30 then gets bright shade the rest of the day.there are orange streetlights brightly shining about 20 feet from my plants,will this affect flowering.