Healthy Dryadella edwallii won't bloom

[dlewan]

Below please find a picture (slightly out of focus - sorry) of my Dryadella edwallii and Pleurothallis niveoglobula. I got them both from Andy's Orchids at the same time. I think they're doing well; the new growths are strong and they get enough light that the leaves show pigment. The P. niveoglobula doesn't just grow but blooms. One tiny flower is visible in the picture. It actually had 6 flowers when I took the picture.

The D. edwallii, however, hasn't bloomed for me. I'm on a window sill, S-SW facing. Daytime temperature can get to 25°C. (24° is common.) Nights are a little cooler at ~20°. Humidity is consistently around 50%. The distribution map at POWO (vague as it is) suggests to me that the temperature ought to be reasonable.

Any help? Is there something obvious that I'm missing?

Thanks.

[Louis_W]

Is there any seasonal change in light and temp?

[dlewan]

In reality, no.

I suppose I could change it, but it wouldn't be by more than, say, 2°C. Over 100 other plants are quite happy with things as they are. (Is this where I should a little frowny face?)

[estación seca]

It comes from about 27 degrees South so there will be seasonal changes in daylength. Andy's is about 33 degrees North. How far North are you?

[dlewan]

I'm currently in Savannah, GA, at about 32°N.

There's definitely a day length difference. My growing area is "pretty dark" with some moderately distant ambient light. I know that a full moon can mess up some photoperiodic plants. Is D. edwalii among them?

[Roberta]

I would suspect that they're not getting enough cooling at night - especially in winter, but summer is likelty to be an issue too.

[dlewan]

I understand that that's reasonable. (I don't like it, but I understand that it is.)

I know I've been able to "shock" some plants (no orchids come to mind) into flowering with, say, 3 days of some outrageous treatment. Longer than that will take some concentration. Of course, I have to find some tolerable short term change for anything.

[Roberta]

If you're still getting springlike weather (temperature variations including some cool nights) consider putting them outside until it turns hot. (Maybe too late?) Then when things cool off in the fall,you can put them out until nights get into the low 40's F.