Need Grow Light Guidance for Cattleyas to Bloom

[realoldbeachbum]

Hello OB. It is me realoldbeachbum, once again with a question. I need advice on lighting, specifically what it will take to get my Cattleyas to bloom.

I understand that Cattleyas need 2000 - 4000 foot -candles to bloom. So that is my goal, in foot-candles.

History: About a year ago (without knowing anything about lighting and foot-candles) I purchased Monios-L T8 Full Spectrum LED Grow Lights from Amazon, based on user reviews. Under these lights, my Cattleyas are healthy and putting out new growth and roots, but NOT ONE OF THEM is even attempting to sheath. [They get about 6 hours of T8 light per day – about 4” from the lights, with perfect humidity, food, ventilation and water.]

My questions: How in the heck can I find out how many foot-candles they are getting? I can’t find the amount of “foot-candles” on Monios-L website (they measure in terms of “nm’s”, not foot-candles), and I cannot find out how to convert from nm’s to foot-candles! Is there even a way to convert? Perhaps I only need to increase the hours and forget about nm’s and foot-candles all together?

If I had it to do over, I would purchase orchidhobbiest.com lights. But, for now I need to work with what I have. Thank you sooo much, OB. All advice is GREATLY appreciated.

[WaterWitchin]

Any reason you can't put outside this time of year? And six hours light a day isn't nearly enough. Go for twelve or so.

[pdxtyler]

So, I'm new to growing under lights. But I have done some pretty extensive research on the topic. I set up a grow tent in my basement about 6 months ago where I've successfully bloomed several mini cattelyas. The plants in the tent get no sunlight. I'm using 3 Spider Farmer 600 LEDs for a 5'x2' shelf. I got these for about $100 each. These however are rated to last much longer than most lights.

From what I understand is with LED lights the important numbers are PAR, PPFD and DLI ... not foot candles or LUX. Many of the lights on Amazon have very misleading specs as far as wattage and false claims camparing to halogen lights.

Cattleyas require a DLI of 10-15 (daily light interval). According to Amazon, the monosL T8s put out a PPFD of 181 at 8". So at 6" maybe lets call that 200 PPFD. Now to calculate the DLI, I use an online calculator like here. So 6 hrs at a PPFD of 200 you're getting a DLI of 4.3. If you bump up the time of your lights to 15 hours/day you'd get an adaquite DLI of 10.8.

Another important thing to look for when buying lights is how efficient they are. This directly equates to how much heat is being put off and how much electricity is being used for the same amount of light being put off. Most lights don't give this stat. Spider farmer lights are amongst the highest at 2.7 umol/J. This is imprtant for me as my grow tent does not need vetilation with the heat output.

I hope this helps.

[realoldbeachbum]

Originally Posted by WaterWitchin

Any reason you can't put outside this time of year? And six hours light a day isn't nearly enough. Go for twelve or so.

Thanks WaterWitchin. I cannot put them outside. It is 100 degrees with blazing sun right now and it is only 11 a.m. Since I have had them inside for the last 2 years or so, I think they would burn. Short of any other guidance I will increase the hours and forget about calculating foot-candles. Appreciate your advice.

---------- Post added at 11:01 AM ---------- Previous post was at 10:53 AM ----------

Originally Posted by pdxtyler

So, I'm new to growing under lights. But I have done some pretty extensive research on the topic. I set up a grow tent in my basement about 6 months ago where I've successfully bloomed several mini cattelyas. The plants in the tent get no sunlight. I'm using 3 Spider Farmer 600 LEDs for a 5'x2' shelf. I got these for about $100 each. These however are rated to last much longer than most lights.

From what I understand is with LED lights the important numbers are PAR, PPFD and DLI ... not foot candles or LUX. Many of the lights on Amazon have very misleading specs as far as wattage and false claims camparing to halogen lights.

Cattleyas require a DLI of 10-15 (daily light interval). According to Amazon, the monosL T8s put out a PPFD of 181 at 8". So at 6" maybe lets call that 200 PPFD. Now to calculate the DLI, I use an online calculator like here. So 6 hrs at a PPFD of 200 you're getting a DLI of 4.3. If you bump up the time of your lights to 15 hours/day you'd get an adaquite DLI of 10.8.

Another important thing to look for when buying lights is how efficient they are. This directly equates to how much heat is being put off and how much electricity is being used for the same amount of light being put off. Most lights don't give this stat. Spider farmer lights are amongst the highest at 2.7 umol/J. This is imprtant for me as my grow tent does not need vetilation with the heat output.

I hope this helps.

OMG pdxtyler, that is excellent information. I will definitely increase the hours! Thanks so much.

[WaterWitchin]

Yes, if they're only getting six hours a day, not nearly enough hours. I think with those lights you'll do just fine if you up the hours. I grow six months out of the year under cheap shop lights, and mine bloom.

I understand hot. And you're right, if they aren't outside and haven't been, now is not the right time to introduce them to summer. Mine are doing just fine at 100F or so, BUT they've been outside since temps were in high fifties, low sixties. And you don't have issues with grasshoppers eating leaves as I do, so there's an added bonus.

I know not much about foot candles vs lux vs lighting in general. I just stick them under my shop lights and go forth, so not much advice I can give there. I do have a cheapie light meter that's fairly accurate. If you're interested, just look up on Amazon or I'll find the name of mine in a day or so. (I'm not at home).

[JScott]

I use T5 fixtures that are 4 feet wide with 4 bulbs. I keep the tops of my plants about 2 to 6 inches below the lights. I run them for 14 hours a day every day all year.

---------- Post added at 11:20 AM ---------- Previous post was at 11:15 AM ----------

You can bloom Cattleyas with the new LEDs with just two or three bulbs, but certainly not in 6 hours. If you're using T5s, you need four per fixture, and you need to leave them on for 12 to 14 hours. You might be able to do better with LEDs. I'm planning a new setup, and I'll be using LEDs.

[estación seca]

An unvarying 14 hour daylength will likely keep some plants from blooming. A flowering trigger for many plants is variation in day length.

[JScott]

Originally Posted by estación seca

An unvarying 14 hour daylength will likely keep some plants from blooming. A flowering trigger for many plants is variation in day length.

Then it's a good thing I put them outside in the summer.

[realoldbeachbum]

Originally Posted by WaterWitchin

Yes, if they're only getting six hours a day, not nearly enough hours. I think with those lights you'll do just fine if you up the hours. I grow six months out of the year under cheap shop lights, and mine bloom.

I understand hot. And you're right, if they aren't outside and haven't been, now is not the right time to introduce them to summer. Mine are doing just fine at 100F or so, BUT they've been outside since temps were in high fifties, low sixties. And you don't have issues with grasshoppers eating leaves as I do, so there's an added bonus.

I know not much about foot candles vs lux vs lighting in general. I just stick them under my shop lights and go forth, so not much advice I can give there. I do have a cheapie light meter that's fairly accurate. If you're interested, just look up on Amazon or I'll find the name of mine in a day or so. (I'm not at home).

Thanks WW. Next year, I might put them outside, but will need to come up with some type of shade. I HAVE NO SHADE IN THIS BLAZING AL SUN! But, for this year, I will increase the light inside. Just now I bumped it up from 6 hours to 10 hours, and within a few weeks will bump it on up to 14-16 hours. (I have the lights on KASA timers and can change on my cell phone! Technology at its finest.)

I will invest in a light meter just for good measure.

I am incredibly envious of you seasoned orchid growers that can just 'stick them under some shop lights and go forth'. I became interested in orchids only 3 years ago, and now have 58. I am definitely in over my head; but I LOVE IT!!! Really appreciate your advice.

[estación seca]

Originally Posted by realoldbeachbum

...light meter.... seasoned orchid growers....

It won't take you long. Most of us go by the color of the leaves and the tightness of growth. Electric lighting can be confusing because the lamps drop off in light emission as they age. It is so slow our eyes can't tell the difference, but the plants can. People tend to change fluorescent fixtures every 9-12 months, for this reason. I still have stockpiled some 4' / 122cm long standard cool white fluorescent tubes I use for sprouting cactus seed indoors. I write on the tube with a Sharpie pen the date I put them into service. When the time is up I replace them, then move the tubes to the fixture in my laundry room.

Also, the more well-grown plants you see in other people's collections, botanical gardens or the wild, the more you'll realize what things should look like. That part is harder right now.

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.)