Winter rest requirements for Dendrobium harveyanum?

[camille1585]

Originally Posted by estación seca

I'm sorry. I didn't respond earlier because I haven't grown this one and haven't talked to anybody who does. I didn't want to offer useless random speculation.

But I have found this article, which didn't appear the last time I searched on this plant, months ago. It is written by an orchid expert:
Dendrobium harveyanum

Thanks for the link, I had seen it as well. They grow in a greenhouse though, where I expect humidity is going to be different (higher) than indoors. I'm not looking for input from someone who specifically has this species, general watering advice for 'dry rest' in indoor growing conditions is fine too.

Like I said I can move the plant to another cooler room, and stick it between the window and curtains but it won't get cooler than maybe 15C there, still with low humidity (and no supplemental light).

And heck, worse thing that can happen is that it doesn't make larger spikes. I'll still be happy with the 2-3 flowers I get, since I know it's difficult to do much better. (and better than no blooms at all!)



ShadeFlower, while I do appreciate your input and do agree with you on your opinion for most orchids, for winter resting Dens I do not agree. Cool and/or dry is what these types of Dens naturally get in the wild, and it is well known that for many of the winter resting Dendrobium types, cool and/or dry are important triggers for blooming. See the link ES posted for a fine example of this.

[estación seca]

Here is speculation. Monsoonal climate terrain I've been to in Mexico has very arid winters with low humidity unless the locale is quite close to the sea.

[Roberta]

I haven't jumped in on this one because my growing conditions are really different than for people who grow indoors. I have a bunch of deciduous Dens from the similar Himalaya, China SW and SC area but not this particular one. (I think I need it... I love frilly orchids!) I generally don't dry them out particularly, but they do get a lot colder than they would indoors. And bloom. (It is also likely that "wet" where I live, watering for a minute or two every few days with only occasional rain, is closer to "dry" in habitat where there is humidity and dew.) So, I wonder... maybe there is more than one "right answer"! They may not need "cold and dry", maybe "cold or dry" does the job. Since none of us lives in the habitat, everything we do is a compromise, and sometimes we hit on something that works!

[camille1585]

Great news, I'm pleased to report that my Den harveyanum is starting 3 spikes right now!

I stopped watering and fertilizing around the time of my original post (late october), and throughout the winter I lightly misted the top of the substrate 1-3 times a week. I was planning on starting watering again around Valentine's day, but started today on account of the spikes growing.

[camille1585]

Thank you all for the excellent advice last year. The flower count is a big improvement over last year's blooming!

Next resting season I will try to keep it a bit cooler to see if that further improves the flower count.

[Roberta]

An observation from my Dens this year... I didn't dry anything out, was not able to move my plants around due to surgery that cramped my style for a couple of months. (Starting to get back to work on the orchids) Den nobile types in particular... they didn't get dried, but they did get chilled (complements of Mother Nature). And blooming better than they have for a long time. Lots of other deciduous and semi-deciduous Dens (mostly mounted or in baskets) I never move away from water following the "Andy" approach, and they're budding too. So I suspect that "rest" has both a "dry or drier" component and a "colder" component. and for at least some, one or the other alone may be sufficient. Some species likely are fussier than others as far as needing both, but it may be a continuum.

[camille1585]

Thanks for the insights Roberta!

For my Den it will be difficult to know if cool+dry is necessary, or if dry is an acceptable (though suboptimal) substitute to cool. I live in a very well insulated apartment in a climate not at all compatible with keeping an orchid outside all winter.

[Roberta]

Another thought about a factor for triggering Himalayan Dens... increasing light. In nature, when the rain goes away, so does cloud cover, so they are exposed to much more light. When growing under lights, that is something that could be tested that isn't possible to control when growing al fresco.

[Dusty Ol' Man]

Putting this here because it fits. After reading this today, I went out to check and maybe add a spritz of water. Lo and behold, there is action! Thanks to all the contributors to this thread. You keep me sane through the waiting.