Dendrobium speciosum dry period

[smweaver]

In regards to Dendrobium speciosum (and particularly for those of you how have flowered this species successfully), I'm interested in finding out how long of a cool and dry winter rest you give them. I know they have to get big, lots of very bright light, etc. before they're able to bloom. I just need to get a general idea of what qualifies as a cool and dry winter rest period is needed in order to initiate spikes--one month, 6 weeks, three months, longer? And how dry is dry for this period. The Baker cultural sheets for this group indicate the following for the winter rest:

Cultivated plants should be allowed to dry out somewhat between waterings, but they should not dry completely or remain dry for extended periods.

If this is accurate, it would appear that a complete dry period is neither needed nor desired as part of the rest. But that's just my interpretation.

Anyone have any thoughts?

Thank you!

Steve

[estación seca]

I think the cool is more important than the dry. People grow them outdoors in southern California, where they may have nights in the low 40s F (sometimes lower) and days in the 50s-70s. They get variable amounts of cold winter rain.

[Roberta]

My advice may not be particularly useful since I'm not trying to reproduce natural conditions indoors. Living in a climate close to what they get naturally, it's 'way easier. I don't dry them out at all (other than watering less frequently when it is cold because things don't dry out as fast, but that's for everything) What they do get is a natural chill. Winter night temperatures can occasionally get down pretty close to freezing ( mid to high 30's F, 2-4 deg C, low 40's F/4-5 deg C is typical) Days warm up somewhat even on the chilliest days. (Mid to high 50s F/10-15 deg C ) or warmer. Fairly bright but not necessarily really sunny. And they bloom profusely in the spring. So I'm convinced that the cooldown is really important, drying not so much. How much? I don't know... since it's whatever Mother Nature throws at them at my house. Certainly, getting down to 50 deg F/10 deg C or so for 2 or 3 months of winter might be a good place to start, a little cooler would be even better.

This is the approach that I use for the deciduous Dens too... don't dry them out, they get chilly nights. In nature, even if there isn't a lot of rain, they experience humidity and heavy morning dew so definitely don't dry out. I killed a few Den nobile types in early career by following advice to dry them out.(" From Halloween to Valentine's Day" Baloney). My climate is 'way too dry for that to work. (Learned the hard way) And not drying them out at all doesn't seem to inhibit blooming. It's the chill that seems to be the bloom trigger.

[Jeff214]

Mine is watered and fertilized heavily year 'round and spikes emerge around Dec-Jan once the temperature drops to the 50s at night.

[Roberta]

Coastal California spring shows (from San Diego to San Francisco, Feb/Mar range) are always wall-to-wall Den speciosum and relatives. And everybody grows them outside, no particular protection - a region of perfect climate for them...Mostly frost-free but cool in winter, moderate moisture. (Definition of an easy orchid - one that you don't have to do anything special for.) Most of them, they stay in the same place all year around, too big to move.

[stonedragonfarms]

Ditto what Roberta and the others state; I pretty much follow similar culture as for Cymbidiums, but grow potted speciosum in a much leaner/faster draining media. Mine get quite cold over the winter months, sometimes into the upper 30s overnight and not a lot of sun [Portland here, positively devoid of sunshine the bulk of the winter months...]

[smweaver]

Thank you, everyone, for the great replies to my question, and for sharing your experiences. I do grow the speciosums outdoors from late March until as long as possible, which usually translates to somewhere around the beginning of November. The nights here routinely drop between the mid 30's and high 40's from September until November. Basically I leave the plants outside as long as the temperatures stay above freezing--and even then I still end up tempting fate on some nights in an effort to give them as much of that chilling period as possible (moving them up against the house or beneath the roof of the porch to give a bit of protection if it's predicted to be borderline freezing). Fall days here are warm (usually), so there's a big temperature differential in the two months I have them outside before they need to be brought in (yesterday's high was 70 and it dropped to 38 overnight).

I have been following the advice given on the Baker culture sheet regarding watering. And the temperature differential at this time of year usually means the plants are completely covered with moisture from condensation by the time the sun hits them in the morning. The plants I imported from Australia in 2016 as seedlings are finally getting bigger, with lots of large "eyes" where spikes could emerge on the largest growths. So I just want to make sure that I'm doing everything possible to encourage blooms.

Thank you again for the excellent empirical data you provided!

[Ray]

The one and only dendrobium I have grown in 50+ years was D. speciosum v. hillii, a tiny seedling in a 2” pot, given to me after my “big freeze” in 1994.

It survived any and all attempts to ignore it, stayed in the greenhouse year round, hung up with the vandas, and received no special rest period. In 2008, it bloomed for the first time on 18”-24” canes, with 36” spikes.

I promptly gave it away, and it and its multiple divisions, are now residing in upstate SC.