T8 fluorescents - how far from the leaves?

[silence882]

Hi All,

I have a quick question for those of you that grow indoors using T8 fluorescents. How far do you have the top of your slipper leaves from the lights?

Right now I've got 4-bulb fixtures 8" from the top of the leaves.

Thanks!
--Stephen

 

[gonewild]

8" is OK.
I had phrag leaves grow past the tubes and were fine except when they actually touched the tube they sometimes got burnt spots. (from the heat of the tube not the light intensity)

 

[troy]

Check my collections thread, I use t8s

 

[mrhappyrotter]

Sounds about right to me, too. I have my shelves set up with variable heights, and I'm growing and flowering Parvies and other Paphs with lights at about that range, possibly even higher than that. On the other hand, I keep most of the Phrags and multifloral Paphs in higher light, and a little closer to the bulbs. There are some like my Eric Young that do fine in the lower Paph light, but the rest prefer it brighter. Small plants get lights within inches of the leaves (and sometimes grow up into the bulbs as already mentioned), but only if they can tolerate that much light.

 

[Justin]

Are you talking about 4' lamps? If so 4 of them that close is too much light.

 

[naoki]

Interesting. I haven't used T8 for a while, but even with T8 LED with more light (mine is 4x Sunritek 12W 4' bulb), Paphs seems to be ok with around 8-10". I think I have P. volonteanum, P. sugiyamanum, P. gratrixianum, and P. dayanum. I think they are getting a bit less than 1000fc. But as Justin said, they may grow ok with less light.

Other environmental factors influence the appropriate amount of light, too. For example, plants may not be able to handle higher light if RH is too low or plants are no well hydrated (they don't want to open stomata, which causes lower net carbon assimilation under strong light). So you do need to experiment (safer to start from more distance). Also, if the plants didn't have artificial light before, there could be an acclimation process to the constant light. So you may see slight lag before they start to grow.

 

[silence882]

Thanks for all the tips!

My plants were getting way too little light before and have greened up since I switched out bulbs. I'll keep a close eye on them to look for any bleaching.

 

[Happypaphy7]

It depends on the plants as has been mentioned.
I recently started growing some plants under the light. I have two shoplight fixtures each housing 2 bulbs of T8.

The plants are about 8-12in below the light depending on their height.
I have parvis, brachys, (and hybrids of these with multi), maudiae type hybrids and species (barbata section) and bulldogs.
It's been about three weeks, and everything except for a couple of plants from the barbata group and maudiae hybrids (which were getting bleached, hence moved out of the light set up, and they greened up the next day, strange!) seems to be alright.
I actually see brachys responding well already, but it's growing season any way.

Parvi x multi hybrids which were yellowish because I gave them a lot of sun are actually turning greener under the light.