Growing Cattleyas under PAR38

[ALToronto]

Originally Posted by Gravelsack

Not exactly the greatest picture, but I thought I'd show what happened when I put my C. luteola about 4" away from my Maxspect Razor. You can see by the little hemisphere shaped mark on the smaller leaf that the discoloration only occurred right where the light was hitting it. The same is true for the marks on the other leaves as well.

I have since moved it down away from the light.

Attachment 108812

That is a burn. Mor's cattleya is nowhere near that.

[terryros]

I increased the amount of LED light impacting my orchid collection a year or two ago, based on light meter readings. The results were beneficial for high-light orchids like Cattleyas, Dendrobiums, and I think even Miltoniopsis. However, with Phals, Paphs, and maybe Phrags, it is a question. The great majority of my Phals have the latest 2-3 leaves much shorter and rounder than the previous leaves. These leaves are also thicker. The distance between each leaf is also very short. Most of the plants have still spiked and bloomed, but the spikes are shorter than previous. I think the flowers are still about the same size, but the distance between flowers on the spikes is smaller on many. With Paphs I have also seen shorter, rounder, thicker leaves and short flower spikes.

I have not had any other major change in growing conditions so I can't attribute the changes to anything other than light. While I am attracted to the more compact size of my Phals and even the shorter spikes, Jerry Fischer of Orchids Limited thinks the overall flowering of the Phals under high-light effect won't be as good. As an experiment, I am backing off almost 50% on the light intensity for the Phals.

With the currently available high quality and efficient LED lights, you can choose the correct beam angle to provide varying light intensity for your orchids. With the ALT Par38 30 watt, 100 degree bulb, 9 inches below the bulb you are covering a good 22 inch circle with high-intensity light. Jerry Fischer is still a little worried that this may be too much light even for Catts, but we are going to find out. I think the horizontal orientation of the Phal leaves (and many Paphs) will react differently to the collimated light from the LEDs than the more vertically oriented leaves of other genera.

60 degree beam angle lights give a 22 inch circle about 19 inches below the bulb and 40 degree bulbs create this light circle at about 30 inches below. PAR meter readings at these levels are 25-40 micromoles/M2/sec in these circles, which would strike most as low, but the collimated light of LEDs does not appear to always behave like other light sources.


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[Gravelsack]

Originally Posted by ALToronto

That is a burn. Mor's cattleya is nowhere near that.

True, but the photo answers his question: "They can't burn in any way because of the leaves temperatures, right?"

The temperature of the leaves was quite cool, but they burned under high light intensity nevertheless.

[terryros]

There is a biochemical basis for leaf burning (that I can't describe but have read) under light more intense than a plant wants even though temperatures are not elevated. The two reasons I switched to LED lights 4-5 years ago were to reduce heat production and to be able to have the light source higher over my plants. I didn't need the growth to be superior to what I had with fluorescent/compact fluorescent lights. I also needed to be able to reduce the electricity drain in the plant room so I wouldn't be triggering the circuit breaker all the time. All of these things have been wins. Although I have seen high-light effect on various genera, I have never seen burning.


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[Mor]

Oh wow, so many replies. I'm happy to see that my short update and few questions turned into an informative discussion.
It's interesting that a leaf can get burned only by the light intensity only. I do increase gradually the artificial LED light hours and I'll keep doing doing it until summer arrives. I add +1 hours per month until June. Right now the lights working for 11 hours.

Thanks for the information and your kind advices.
Mor

[merkity]

where did you get your light from? i have been looking around to see what I can find, can't seem to quite find the right bulb.

[terryros]

I have purchased all of my lights from Orchids Limited, Plymouth, MN. I think they may still be the primary importer of ALT lights from Asia. I think these lights are thought to have the best heat dissipation technology. You can easily unscrew a bulb that has been on for hours and not have it be very hot in your hand. OL has various bulbs and typically in either natural white or warm white varieties.

The MR16 7 watt 40 degree bulbs are the most efficient by the specs with 650 lumens for the natural white variety. The PAR30 15 watt 60 degree variety are 1050 lumens for natural white. The PAR38 30 watt 100 degree are 2400 lumens for natural white.

I know you can find cheaper bulbs, but the chip sets, construction, and lensing on these bulbs are thought to be first rate. I looked at these as a long term investment to gain various improvements in the plant room.


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[DelawareJim]

I get my lights from Build My LED. I highly recommend them.
Build My LED Custom LED Lights for DIY Horticulture Aquarium Hobby Lighting

The owner Nick Klase, used to work for one of North America's largest horticultural lighting companies before he started his own business.

I've worked with him directly to configure the best setups for my growing area and my aquariums and he's great to work with. He provided PAR maps to show me how much light reaches the different parts of my grow area and tanks, and recommended the best lens degree angles to get the best coverage.

Each fixture is made to order and he uses the best BIN Osram LED emitters available.

I'm a horticulturist, and when we talked about PAR (Photosynthetically Active Radiation), and the other key measurements like PPF (Photosynthetic Photon Flux), and PPFD (Photosynthetic Photon Flux Density) he knows what he's talking about.

For those who live in the Mid-Atlantic area my aquarium club is hosting the annual convention in Washington, DC and Nick will be speaking about LED lighting. While it will be tilted towards aquarium plants, the basics are the same for any plant and I'm sure he would be glad to discuss lighting for orchids after his talk.
Aquatic Gardeners Association Convention

Cheers.
Jim

[merkity]

Thanks! have to take a look.

[Mor]

Hey merkity,

I purchased mine also at Orchidweb.com. I live in Tel Aviv and no one in the middle-east sell them (and if they do they do not ship to Israel because.. Well, take a guess ) so I even looked for it in Western Europe but I didn't find the specific bulb - the natural white. So, Orchidweb.com were my only option. But I have to say that although it's extremely expensive - it is start to seems that it was really worth it. Except of my "purple" Catt. all of my Catts seems much more healthier then few months ago. (And as few users comment on this thread my "purple" Catt. Is in great condition too).

Good Luck
Mor