Need Grow Light Guidance for Cattleyas to Bloom

[estación seca]

I've only used electric lights in winter in climates with poor winter light. Here in Phoenix I grow under natural light.

[Dorchid]

Gotcha! I would think it would almost be the reverse in Phoenix...plants inside during the summer. 🥵

[estación seca]

I have a sunroom. I cool it with evaporative cooling. They get natural light through the sliding glass doors and the glass windows.

[WaterWitchin]

Originally Posted by Dorchid

I meant to ask a clarifying question, being, was that 8 hrs year round or just winter? I then started thinking maybe between those and cutting it down to 10 hrs in the winter.

WW - Was that 12-13 year round?

Winter months (mid to late October through April) 12-13 hours of lights on each day. Last two years 6:30am to 7:00pm. They are in a basement, no other light available. I'm attempting to mimic the range of daylight hours received by them in their natural habitats, averaged over the type of orchids I raise for the most part.

Summer months (May through mid October) no lights at all. Plants are all outside.

I did play for quite a while lowering light hours for several months in winter, sort of mimicking the amount of light they would receive if outside. Then decided 1) I didn't want to mess with it or forgot, and 2) I was following natural daylight hours in Kansas... not too many orchids growing naturally in Kansas. It was a bit of bad overthinking on my part.

---------- Post added at 08:19 AM ---------- Previous post was at 08:13 AM ----------

PS Dorchid, you might consider putting your state location into your profile. I can't ever remember where you're from, and it's very helpful to folks.

[Dorchid]

Thanks for clarifying, WW! I’m in CO.

[thefish1337]

I grow my cattleyas between at 300-350 ppfd for 12 hours in the summer, and then adjust to 10 hours in the winter, I keep the DLI roughly the same by lowering the lights a bit to compensate for the loss of photons. I grow some under an HLG 65 4000K and a HLG 100 3000K and some under a 3500K chinese creecxb3590 fixture. Haven't noticed too much difference between the spectrum. I haven't seen more flowers under the red spectrum, or better vegetative growth under the blue spectrum. I like the warmer spectrum because its easier on the eyes. I think the color temperature is more a consideration for fluroescent/HPS/CMH lighting which have completely different spectrum composition than white LEDs.

[Steve83]

I have heard good things about the HLG units from my local hydroshop. HLG and cmh units are the only lights that he carries anymore, which says a lot given how much money is on the line (doesn't make sense for him to carry cob leds bc most just buy kits online).

I was thinking of doing something similar in regard to adjusting my photoperiod, but the change isn't even an hour (only have tropical American genus atm). Maybe I'll adjust the timer 10 minutes every quarter.

[terryros]

If you look at the winter and summer day lengths for natural environments for the major unifoliate Cattleya species you find that nothing gets less than 11 hours of day length in the winter and nothing gets more than 13.5 hours in the summer. You can certainly give more in the summer and less in the winter and most plants probably adjust, but if you are trying to mimic the natural environment, 11.0 - 13.5 would cover these species.

[nuriko1set]

Originally Posted by estación seca

It won't take you long. Most of us go by the color of the leaves and the tightness of growth.

Rather than a light meter, you can observe shadows. Put your hand between the plant and the light source. If the light casts a sharp shadow of your hand, it is very bright light (best for many Catts, Vandas, Cymbidiums.) A distinct but not sharp shadow is bright light (tolerable for many Catts, Vandas, Cymbidiums.) A blurry, indistinct shadow is low light (Phals.) No shadow is very low light (jewel orchids.)

Thank you for the information!

I have a light meter, and I measured my Cattleya getting around 1500 - 2000FC. I'm not sure about the other information. such as PPFD. For my next light I"ll have to do a bit more research about lighting.

I understand the effects of the leaf colors, but how does lighting effect tightness of growth? Does more light mean tighter growth or the opposite?

Thank you!

[thefish1337]

typically more intensity will make for "tighter" growth and less or inadequate will make the plants stretch to the light. hard to overcome the genetics of the plants though- I have some cattleya that will sprawl no matter what light they have on them.