Growing Cattleyas under PAR38
 

Hello!

I am growing few orchids which required high light such as Cattleyas, Brassovola Nodosa and similar. Because I have only northern window my orchids didn't bloom.

I recently purchased the ALT PAR38 LED 60 degree 30 Walt bulb for my Cattleyas.

The salesman told me that this bulb is "perfect" for cattleya's growing. Unfortunately when I measure the light it's seems that my orchids gets 17,000 LUX ~ (1200 FC ~).

Do you think it's enough? What do you recommend me to do? I have no sun at my flat and I really want them to bloom. I'll appreciate any kind advice!

Do you think I should buy more bulbs?

I attached photo of the bulb package and photo of my growing shelf.

Thanks!!!!
Mor

More photos
 

More photos

And the bulb pack

With some daylight, it's plenty of light. Watch for leaf tips becoming light green to yellow - that will mean too much light. I hope you're giving the plants at least 12 hours of darkness in the winter, they need to rest as well. Then gradually increase the duration to 16-18 hours in the middle of summer.

First, under artificial light for the 11-15 or so hours we should be illuminating the plants (depending on time of year), you need 50% or less light than the peak light figures that you see (which are for sunlight).

On top of that, LED lights are different. I am using 4 of the lights that you bought. I use a specific light meter that measures more directly peak photon flux as a better measure of light in the photosynthetically active range. At a distance of 7-9 inches from these bulbs you are getting plenty of PAR light. Even on top of that, it is starting to be evident that the way that LED light comes out (straight down and out) creates even greater photon density on leaf surfaces. So, it may take even less light than we think with these LEDs. For now, I would keep your Catts 7-9 inches away and watch them. I have had my Catts under these lights for about 3 months now. I am not seeing evidence of too much light, but they are growing well with a big Jose Marti coming beginning to bud out.

Thank you both!!
 

Hey, thank you both for sharing this important information!!

I did get some recomendation for this specific bulb and I really hope it will be worth it.

I will set the timer for 12 hours of darkness as you recommended. At this time the Catts are 25 CM (9.5 inches) away from the bulb.

I think I'll buy another one for the same shelf and I'll arrange it differently because of the lower bulb angle.

Thanks!! I'll keep you updated.
Mor

You want to change the day length through out the year because some orchids will only bloom in response to an increase or decrease in day length. You don't need to go shorter than 11-11.5 hours and don't need to go longer than about 14-15 hours with these lights.

With these bulbs, 8 inches (20 cm) below the lower edge with a 100 degree beam angle you are covering about 20 inches (50 cm) of growing space (in a circle). So, your lights can be about 20 inches apart to have minimal fall off in light intensity in between the lights. Two of these lights can thus nicely cover at least a 40 inch wide growing zone. There is certainly still some light out wider than this in all directions but it will be weaker.

Sounds right
 

Hey terryros,

Thanks again.

because I'm a new orchid grower any kind of info is really helping me to make my growing environment to the optimal. I am reading a lot on the web and on this forum as well but it's un-comparable to communicating with other mature growers.

Do you think that placing Paph's on the edges of the shelf is ok? or it might be too much light for them? (the bulb angle beam is 60 degree) and when I check the light level on that spot it seems quite all right..

Good Day,
Mor

Obviously, the light intensity falls off at the periphery of the light. In addition, the angle of incidence of the light to the leaves is less vertical, and that might make a difference. But, we are all in uncertain territory with LEDs and orchids and our light meters (standard or PAR) are likely not telling us the whole story. I think that each of us just has to experiment and watch our growth and flowering, at various meter readings.

So, go ahead and put some lower light Paphs or Phals on the periphery and see what happens.


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A short update
 

so everything seems to be fine with the ALT Par38 bulb except of my purple Catt. Her leaves turned purple! And I mean that all the leaves turned really purple! It's not only the tips.. I attached a photo. Is it bad?

Is anyone think that high level of artificial light can harm low light growers? They can't burn in any way because of the leaves temperatures, right?

Thanks!!
Mor