Hello,did any of you have ever had this kind of problem with his plants grown under lights?Mine are developing small leaves,and their current sizes are half of their previous one.I can't figure out why...they seem happy,they grow,they bloom,but they're becoming dwarfs!!!
This phenomenon occurs on every orchid in my orchid case,no matter the species.Paphio and Phrags also seem affected,but more slightly.
I'm growing under a 150 w HQI light,and I don't think it's due to a lack of light,because plants bloom,(Cattleyas and Ryncholaelias too).
Maybe a too long lasting photoperiod? (16 hrs).
Temperatures are 17 C° night and 23-24 C° day
Moisture: 70%
I'm feeding them "weakly weekly" with Peters 20/20/20 + aminoacids + seaweed (but not always all three together).
Thanks

it could be insufficent light but usually plants grow long leaves when they dont get enough light. interesting!

What color of green are the leaves? A darker color means they aren't getting enough light, and a lighter green means they are getting too much.

It sounds like it is a light issue.

Are your plants getting any natural sun light?

What is the spectrum of HQI light? I'm not familiar with that...

I wonder why all your plants are turning into dwarves! LOL I also think it has something to do with the light they are getting.

pictures of the plants would help too.

Thanks for your kind interest.
Paphy:leaves are quite bright green,and some (Cattleya's one and Brassavola's one) are slightly reddish.I thought it was good,since everything blooms.But maybe it's too much.
Casey:you reminded me that when I grew roses and other kind of flowers on a really sunny balcony I noticed the same problem.But my orchid case doesn't receive any natural light at all...
Justin:HQI spectrum ought to be rather complete,with peaks on blue and red.Some friends of mine use them on orchids without having any of this problems.I'll ask them how many hours a day do they keep them switched on.
And I'll take some pictures as soon as possible.
have a nice day/night (it depends on your location!;))

It could be that 16 hours of light is too much.

What is your potting mix and how are the roots looking?

Most of the plants are mounted on cork slabs;calcicolous slippers are potted in bark/dolomite and Phrags in bark and lava rock.Roots are healthy,both those of the mounts than those of the potted plants.
Those potting mixes are the result of a long list of essays with several materials (chc,rock wool,sphagnum etc) and they are the ones that work best for my conditions.
I think I'll try to decrease the photoperiod's length and see what happens...but not right now:I've got 5 slippers in bud and I fear they could blast...
I'll keep you updated...

Ok the potting mix sounds good. I've just heard of people getting stunted growth using CHC on some of their plants.

Worth adjusting the light to see if that works.

I was looking at an alternate option just in case that hadn't been explored.

Thanks very much bolero,exploring all possibilities was exactly what I wanted,and every contribution is welcome and useful.
Now that I've heard so much opinions I'm more sure about what to do.
:fcrossed:

Fertilizer?
How often?
Rates?
The redness may be from too cold, too much light, (too much or too little of something) and or from being stressed.
Add additional magnesium & potassium nitrate... that should reduce or eliminate the deficiency.

Also, if you want to run the light 16 hours, try running them for 12 hours on, a four hour dark cycle, then another light cycle for four more hours in the middle of the night, leaving four more hours of dark before the cycle repeats.

Also you may want to add CO2 to help with the growth. Your orchid case may not have enough air circulation from "outside air" and the air may be CO2 deficient.
Adding CO2 would defiantly increase growth.

My 2 cents worth,
Jim T

Thanks for your reply AHAB,
I feed my orchids every other week with a 20 20 20 fertilizer + seaweed extract,and once a month with magnesio sulphate.The feeding solutions electrical conductivity stays under 350 microsiemens/cm.
What do you mean by "too much cold"? My night temps are 16 c°,are they ok?
Your light cycle is very interesting...
I read somebody added CO2 to orchid cases by inserting a pot with some flour mixed with water and yeast...do you know any other methods?

Another possibility is too much light! I have the same thing happening on a Phalenopsis plant that I found in the garbage can at work. The leaves are less than half the size of the original leaves. They are much thicker than the older leaves and are producing lots of roots in the pot. A very healthy plant but the leaves are small and thick! They start to produce a leaf that doesn't open in half but later open in half at times goes by. It has a slight reddish tinge on the leaf and later turn green as it matures. It is growing under a 400 Metal Halide bulb that is 4 feet above it. On the other hand my Paphiopedilum stonei is loving the higher light it is producing wider and longer leaves.

Paphman910

It definitely sounds like it is light related. Pictures would certainly help if you can post them here.

You're right...sorry,I haven't posted any picture yet...I was pretty tide up at work.
So,here they are.
Phalaenopsis appendiculata: you can see an old leaf on the right and three new small leaves.
http://i44.tinypic.com/14se05f.jpg

Phalaenopsis minus: there is an old leaf on the lower part of the pic (edge-on wiew) and two smaller new leaves (with reddish areas which remind to sunburns)
http://i39.tinypic.com/2it662w.jpg

Phalaenopsis schilleriana: the eldest leaf is on the right part of the pic,reddish and a bit dehydrated (it's ending its natural cycle),whereas you can see three new leaves which are smaller than the former.
http://i44.tinypic.com/4j5clw.jpg

Last but not least,my Cattleya aclandiae...what you see on the lower part of the pic is the eldest growth...that is also the biggest!!! On the upper part of the pic you can see several new growths,very small and red-spotted in comparison.
http://i44.tinypic.com/2coo8c1.jpg

Unfortunatelly I can't take pics of the affected slippers,because of the looming presence in the orchid case of two tall stems (Paphiopedilum philippinense and Pragmipedium Eric Young) that are rather uncomfortable to set aside.
It's a mess,I know...but even if they are as small as dwarfs they bloom!!!!!

I would like to update this thread: after several months of reduced photoperiod (from 16 hrs. to 12 hrs.), the new leaves grown up are considerably larger. Not yet normal-sized, but very improved.

That is great news. Keep up the good work.

Thats awesome...:cool:

thats very nice!!!

Improvement is great news!

You did great! Very well done!

Wonderful news!