Implications of constant 28oC & 80% RH for Phal seedling development - Orchid Board

OzPhal · #1 07-08-2012, 08:22 PM

Hi Folks,

I just wanted to get your thoughts on a setup that I currently have access to for some Phalaenopsis species seedlings and advanced seedlings. I've got access to a growth chamber and am wanting to encourage growth - what, in your thought, would be the implications of leaving the plants at a constant 28oC & 80%RH with an alternating on/off light cycle of 12hrs?

I've calculated the light intensity based on Light Intensity Measurement and approximated that it is around 1,345 lux or 125 foot candles... which, according to some information I've read, is too low for Phalaenopsis although it doesn't look it... holding my hand about a foot above the leaves there is very little shadow

RosieC · #2 07-11-2012, 06:58 AM

I can't help much I'm afraid so really just giving a bump.

I do know nurseries keep then constantly warm to encourage growth and inhibit spikes (to concentrate on growth) but I don't know how warm that is or the details of light and humidity they use.

Oscarman · #3 07-11-2012, 02:11 PM

In my grow room phal seedlings are growing in the 26-30° C day temp and 50-60% RH. They seem to be doing well.

Not sure if 80% will be beneficial of detrimental (increased rot issues?). Not really a humidity level that I have ever grown at.

zxyqu · #4 07-11-2012, 03:02 PM

I'll give my two cents on this. I'll start with what I think is the biggest hurdle, and that is your lighting. 125fc is wayyyyy too low, even for seedlings. If say the species like 800-1000fc, I try to provide 60-75% of that to flasklings/compots. Regardless of the heat and humidity you provide, insufficient lighting will give you really poor growth all around.
The temperature seems feasible, depending on the species, and the humidity is also reasonable. The one thing to be sure of is to provide a bit of air movement. There is some debate on mold/fungus with and without air movement, but I side currently with some (even if minimal) air movement. 12 hour light cycle is fine, but you've got to find a way to increase the light into the 8000-10000 lux range. This is especially true for any seedlings you have that are fairly deep into the compot stage.

Ben Belton · #5 07-12-2012, 01:05 AM

I've grown tons of seedlings, and I'll just say +1 for Jarad and save myself some typing :-)

OzPhal · #6 07-12-2012, 12:14 PM

Thanks everyone for all of your feedback - in regard air movement there's continuous air circulation - attached are some pics of the setup/light intensity

zxyqu · #7 07-12-2012, 12:19 PM

I only see 2 or three that I would still consider giving less light than it would normally receive, but that's stretching it. You've got several NBS plants, and they need the higher light if you want to see sufficient growth and eventual spikes.
Is there any way to put in a few 2' T5 lamps in the roof there. Or maybe through it near a windowsill? This setup looks like something I'd have in my lab...

OzPhal · #8 07-12-2012, 05:48 PM

Hey Zxyqu, this setup is in my lab... I'm a microbiologist. And yes, I can switch on two more tubes in the setup giving me a total of four on

I can also move the lights closer... I've ordered a light meter off eBay last night - just have to tie my orchids over until it arrives

OzPhal · #9 07-12-2012, 07:17 PM

So I switched on the second bank of lights this morning and this is what I have now:

The next option, if it's still not bright enough, is to move the tubes closer to the plants

I currently have in the cabinet:

P. lobbii seedlings
P. violacea 'alba'
P. speciosa 'alba'
P. parishii
P. tetraspis 'C1'
P. violacea 'blue' (could this be a cochlearis or is there actually a 'blue' variety
P. cornu-cervi 'flava'
P. zebrina
P. equestris 'iloco'
P. coringiana
P. venosa
P. pulchra
P. hieroglyphica
P. fasciata (this one has a seed pod on it but it looks like it's aborting - probably due to the change in conditions putting it in the growth cabinet

P. violacea 'coerulea'
P. sanderiana
P. sumatrana
P. pantherina
P. javanica 'mainshow'
P. cochlearis

zxyqu · #10 07-12-2012, 07:26 PM

Several of those species are going to require much higher light. I we assume the second bank of lights only add another 125fc, you're still around 3 fold short what will really be needed to grow these well. Given that light intensity falls off at an exponential rate, you're going to have to move those plants closer, and it will surely help. Sounds like a great collection as well.