Conflicting information about light for Cattleyas - Orchid Board

Alvaro78 · #1 08-15-2024, 12:06 PM

Hello guys! I have started to introduce myself to the world of Cattleyas (I love them so much now haha) and well I am having some confusion regarding their light requirements.

My growing conditions are indoors in a quite tall west facing window. Right now here it's summer in Spain (Madrid) and well you can imagine the heat right now. Soooo I have been reading some stuff and the AOS has some information regarding Cattleya care and they say that even in a west facing window they can receive direct sun because they state you cannot sunburn a Cattleya indoors. Before this info I was growing them with my fine curtains when the sun started to hit during the evening. I also have an app which is kind of popular for light reading called Photone which gives me an aproximate reading and during the evening I'm getting from 100-400 PPFD (about 500-2000 FC) which depending on the source would be sufficient for Cattleyas, but my real question here is whether I can actually give them Spanish evening direct sun to my Cattleyas without any issues if I introduce them to it slowly or if my present conditions are good enough as they are and I should keep them like that.

Thanks a lot!

Roberta · #2 08-15-2024, 01:26 PM

If you want to increase the light, you are right to do it slowly. If they are receiving direct sun, the big factor is heat - the light might not burn the leaves, but if the window radiates enough heat, it certainly can. You will need to observe carefully. When the strong light is falling on the leaves, feel them with your fingers. If hot to the touch, protect them! Your fingertips will give you a far better indication of potential danger than a light meter. It is the "hot spots" that may occur for only a short time, but can be very damaging, that you need to be concerned about.

estación seca · #3 08-15-2024, 01:36 PM

If you aim a fan at the plants it will carry off heat. They will tolerate more sun this way. Here at 33 degrees North I can grow Cattleya seedlings in sun through the window with a fan at temperatures of 42C / 107 F, and probably higher. They dry out much faster and need frequent watering.

Alvaro78 · #4 08-15-2024, 01:40 PM

Thanks a lot for the answer Roberta. I see mhm when I touch them after a while they feel hot but not like scorching hot so I can comfortably put my fingers on them. The room they are at is at like 28-29 degrees Celcius because I have my fans running so that may help too

---------- Post added at 07:40 PM ---------- Previous post was at 07:37 PM ----------

Thanks a lot Estación Seca. I actually have my fans running so my room temperature are like close to 30 so with that info I may actually slowly introduce them to the direct sun with no problems? I also like that they dry out faster since I have changed my approach to a more airy mix with clay pots and bark with a bit of perlite for all my Cattleyas. They seem to enjoy it

estación seca · #5 08-15-2024, 07:19 PM

If you put them in sun in the window I would aim the fans at the plants.

Kittyfrex · #6 08-22-2024, 06:14 AM

I share your climate; it depends. Is it pure west, southwest or northwest. Southwest, i recommend a courtain, tho i've heard some cats can grow in it. The other two should do fine; our climate's sunset is not the killing kind. Just try to leave at least a finger of space between the plant and the glass if it's pure west.

Edit: This is all assuming there are no buildings or trees in front of the windows. Those change...everything.

Alvaro78 · #7 08-22-2024, 06:41 AM

I'm in a pure west facing window and so far I have been giving them evening direct sun to the cattleyas and they seem to like it since some of them started growing out some new roots (the ones bought most recently). They are like 20 cm away from the window.

Kittyfrex · #8 08-22-2024, 06:44 AM

Quote:

Originally Posted by Alvaro78

I'm in a pure west facing window and so far I have been giving them evening direct sun to the cattleyas and they seem to like it since some of them started growing out some new roots (the ones bought most recently). They are like 20 cm away from the window.

From my experience, that should be fine. The fan still might not be a bad idea, just to make sure they don't overheat (that is an entirely different issue than sunburn). If you've moved them within the last month or two, keep monitoring for a while; plants can be quite good at telling you just what is wrong if you know what issues to expect.

Alvaro78 · #9 08-22-2024, 06:49 AM

The room stays pretty consistent at like 26-31°C and when I touch the leaves they are a tiny bit hot, but not much at all and not hot to the touch. I think that may be normal and tolerable for them? But I will keep monitoring at different hours to see how they are doing. Maybe it's my own impression but I do notice some leaves having a lighter green color so that may be a good sign.

Kittyfrex · #10 08-22-2024, 06:55 AM

Light green-yellowish is good in many high light species, especially those that grow outside in our parts, but i am not certain about cat's.

As for hot - use yourself as an indicator; if they are as warm as you, turn the fan on. If they seem just slightly cooler than your skin during the hottest part, there's less than nothing to worry about.
Asuming your room temp is what they are at, that's plenty fine for a wide variety of orchids.

Alas, this is all from my personal experience, and it seems to apply for most very high light orchids i have; when they get to be as warm as me, you start seeing some issues, burns and root die off.