What happens when an orchid doesn't get its winter rest?
 

What happens when a deciduous orchid grown under artificial lighting doesn't go dormant?
I've got a den. bracteosum that didn't go dormant last year and am just wondering if it's harmful in any way. While I'm on the topic, how big does it have to be before it flowers?

Without proper rest the plant will be lethargic and irritable and may not flower.:coverlaugh:
You may get more information in the Dendrobium Alliance.

:goodluck:

Just a thought to get this thread going, I don't think it will hurt anything if a plant wants to keep growing throught the winter. Some Dendrobiums do need to lose their leaves and rest before they can start to flower, but they will let you know by their leaves turning yellow and falling off. This would be a time to slow if not stop watering so that the roots won't rot. I grow all my plants under lights and I reduce the time the lights are on in the fall and ramp it up again in the spring to try to mimic nature. I think by doing this, the plants slow down and in effect rest a little. Having said this, I hope some of the more knowledgeable growers out there will chime in.
John

Thanks John for jump starting this thread. I have grown Debdrobium anosmum continually through the winter and it responded by sending out the new growths in spring with no blossoming. During that period the growths were shorter than normal and not really robust. I gave it a proper winter dormancy (not rest - a true dormancy with no water or fertilizer) and the next spring flowers occurred. Since then I no longer with hold dormancy. As John says, often the plants wanting to rest will go into dormancy even if you try to keep them going. Others might not. My best advice is if you know your plant(s) need or expect a winter dormancy or rest, do it.

I am thinking of getting a nobile type den.-- did you mean you give it no water during the dormant period. How long do you withhold the watering and fert?

I say go for it. I have two D. anosmum and I start withholding water/fertilizer (as in no water at all) on Halloween. I wait until they tell me they are ready to start up again in the spring, usually around March sometime - it's their choice. Then I slowly introduce them to the old water/fertlizer regimen. I never alternate water and fertilizer. I fertilize with every watering. Therefore I re-acclimate dormant plants by infrequent waterings. I start with two a week and work up to daily. Right now they are in daily water/fertilizer mode. Really simple to do. Mine are mounted so they are bone dry by evening even while in the daily water mode. Hope this helps.

Hi Ross, Thanks for helping out on this one. I also have several Den nobile types and I just find it hard not to give them some water every week or so during the winter. With the nobile type, I think you will need to give them lower temperatures to get the blooms started. I let the room go down to the low 60's at night in the winter and up to the high 70's during the day. So far this has worked well.
John

Hmmmm ok... so they need a REAL no water rest starting until november... can they take high light? If so, I can place it on a southern window in winter, and since it gets cold here.. it will be high 50's- low 60's at night in right by the glass. Would that be okay?

Sounds puuurrrphect to me! :biggrin: Mine hang in south window with all the light the Mother Nature chances to dish out (up our way that ain't much :blushing: :biggrin: ) and it does just fine. The nobile Dendros really like high light, which, for 45 degrees latitude and north, means FULL sun! 50s and 60s is great. They actually can take down to the mid 40s without damage while dormant. I suspect the combo of cold/dry winters and warming springs brings them into full bloom. At least for me. I noticed this year that mine started the new growths all reddish color but turned back to green as they got used to the shot of light they covet. I'd say you have the perfect setup and I really recommend a Dendrobium anosmum as a first try. Can't go wrong. Check these posts - http://www.orchidboard.com/community...d-anosmum.html and http://www.orchidboard.com/community...m-anosmum.html In the second link you can see my window setup. That's a south-facing window with added 55 watt CF bulbs directly in front of the plants.

I have a Den primulinum that gave me fits last fall. I cut the water off and backed off on the light to mimick a seasonal change and the only thing that happened is that the three oldest growths on the plant yellowed and died. So I went back to limited watering with no fertilizer and it held its leaves through the winter. About a month ago I started back with more light and slowly increased the fertilizer. Im getting some nice new growth and the leaves on last years growth are now starting to yellow and fall off. No blooms though. I had a friend suggest (think Ive posted this previously) that some of the Dens need a warm kick start in the spring with a sudden increase of light and then could use a good hearty cold snap in the fall otherwise they'll hold the leaves. She said she lets hers get snapped by a light frost and then for two weeks after slowly backs off on the water and fert as well as a decrease in its photo period. So Im going to try it this fall. Anyone else ever let their dens get (or any deciduous orchids for that matter) get nipped by a light frost to induce dormancy?