Mixed Results of Bleaching under T8 Setup

[Happypaphy7]

So, it has been a little over one week since I had some of my plants under T8 light.

As I watered plants today, I noticed that some plants looked slightly (but noticeably enough) bleached and looked rather "tired" while a couple of them looked greener.

First, my set up is three tiers of 4' shelving unit that is 18" deep.
Each tier has two shop light, each housing 2 T8 bulbs.

The distance between the plants and the light is 15-8 depending on the height of the plants. The hours of the light on is 12hours.

The plants involved are mostly parvi hybrids (within parvis and intersectional), brachy species & hybrids, barbarta species & hybrids, bulldog hybrids, liemianum, aerangis.

The results are rather confusing as they are inconsistence.

Bleached:

Rather badly : One (among quite a few) maudiae type plant (complex hybrid)
Slightly: Brachy x roth, venustum seedlings, malipoense x cochlo

Greened up: Delrosi (2), Pink Sky. These plants were yellowish before as I placed them in very high light, so it makes sense.

For now, I moved the maudiae type hybrid out of the light.
I will keep my eye on the slightly bleached group for another week. and of course, the rest of the plants for the next few weeks.
Hopefully they will be fine. headache level going up like crazy already.

I hear people control the hours of the light on to deal with this, but is it really just matter of adjusting the light hours??
I don't think paphs for the most part are sensitive to photo period like cattleyas, but I'm still thinking they respond to photo period to "know" the seasonal change along with differing amount of rainfall and temperature??

Goodness gracious! I was initially thinking of getting T5, and did not expect T8 to be this strong.

 

[ehanes7612]

That's a lot of light for those plants, people tend to underestimate the power of T8s, especially if you have a four feet of ballasts (been there) ..plus you may be drying them out too much . You could substitute them with full spectrum or gro light T8s if they arent already.If they are regular shop lights..too intense of light in a narrow band. I would say either space them out even more or lower the plants

 

[Bjorn]

Do you have a light intensity measurement (F.C. is good enough)

 

[Happypaphy7]

That's a lot of light for those plants, people tend to underestimate the power of T8s, especially if you have a four feet of ballasts (been there) ..plus you may be drying them out too much . You could substitute them with full spectrum or gro light T8s if they arent already.If they are regular shop lights..too intense of light in a narrow band. I would say either space them out even more or lower the plants

Maybe I should buy something like this?

http://growershouse.com/spectralux-t8-ho-fluorescent-grow-lamp-32-watt-6500k

I don't know why it is significantly cheaper than the regular shop lights I bought?
The label says it is good for 9 years, but that is for its original intended use?
I was told I should replace every year, but then some people said they only switch every 2-3 years. Then there were people who switch only part of the light, not all the bulb all at the same time. This is confusing?

Unfortunately, I cannot adjust the distance between the light and the plants.
Each shelf has about equal space and the lights are hanging as close to the top of the each shelf.

I think I will watch the leaf color for the next few weeks, and cover up the light with thin sheer curtain like this Canadian member did with his T5HO.

 

[Happypaphy7]

Do you have a light intensity measurement (F.C. is good enough)

No, I do not have light meter.

 

[gonewild]

Turn off two tubes and see if the bleached leaves darken.

 

[gonewild]

When I had a setup similar to yours I used two timers. One timer turned on one set of lights at sunrise, the the second timer turned on the other set of lights about 3 hours later. This represents low morning light and changes to bright mid day light. Then towards the end of the afternoon the timers reverse to simulate low afternoon light for a few hours.

I dont know for sure if this sequence made the plants grow better or not but it seemed to. In any case it was fun to think it did. Never had any leaves that seemed like they were bleached from too much light doing this.

 

[Happypaphy7]

Turn off two tubes and see if the bleached leaves darken.

I can't turn off individual bulbs as each unit houses two bulbs.
I thought about taking one bulb out and leave three in total instead of four.

Then, I don't want to make any change just yet.
Note the details I included in the original message.
Only a handful is showing any change, and mild one at that.
Plus, some plants are getting greener.

There are lots of plants and they are fine thus far, so I will give more time and take action when more plants look funny.

 

[Happypaphy7]

When I had a setup similar to yours I used two timers. One timer turned on one set of lights at sunrise, the the second timer turned on the other set of lights about 3 hours later. This represents low morning light and changes to bright mid day light. Then towards the end of the afternoon the timers reverse to simulate low afternoon light for a few hours.

I dont know for sure if this sequence made the plants grow better or not but it seemed to. In any case it was fun to think it did. Never had any leaves that seemed like they were bleached from too much light doing this.

This is a great idea.
The fact that all the light bulbs comes turned on all together and turn off all together sort of bothered me. I wonder if that has any effect on the plants, but I don't think very much as many people grow like that just fine.

I had this LED kitchen light set up which was made for growing plants.
That one had this gradual turn on and turn off to mimic the morning and evening dimming as you point out.

The problem with it at the moment is that one, there is only one power outlet to which I have plugged in 6 outlet cord with the timer.
I could have another one but it will have to come from a different wall and I already hate the appearance of power cords all over.
Will have to give it some thought. but this is a great point and it might actually benefit as plants especially paphs might be shaded at some point throughout the day instead of being under bright light all day long like they are now in my set up.

hmmm

 

[garysan]

I was just in the process of writing this (and planning to point out my 'Collections' thread when you just posted on it!

I was going to suggest that you might have a bit too much light there with 2 x 2 tubes. I'm getting approx. 1200/1250fc at the leaves currently which is 'enough' from what I've read/heard. Leaves are approx 11"-14" from lights. Mine are 5ft 58w Daylight tubes which were swapped out with the warm white tubes which came with the fittings. I plan on changing them every 12 months as they're not expensive.

I've only been running it for a couple of weeks but everything seems very happy thus far.

If you've got an iPhone (maybe Android also has an app); I use an app called GreenThumb which utilises the iPhone camera's light sensor and gives a fc reading. Might be worth a look. It's how I got my reading above.

Regarding photoperiod, mine are currently on for 14 hrs and over the next couple of months, I was planning on raising that by 1 hr each month until June (so 16 hrs) and then starting to back it off by 1 hr a month until it 'winters' at 10 hrs for a couple of months.

What temps/humidity are you getting in there?

 

[garysan]

Also, the shop lights you have; do they have reflectors on/in them? I was advised that 2 tubes per shelf was enough without reflectors. If you've got 4 tubes per shelf with reflectors.....

 

[gonewild]

You can turn off any of the tubes by simply twisting the tube a little...not so much that it falls out, just enough so it looses contact on the power.

For individual timers you can get the cheap ones sold for Christmas lights for about $4, put one on each fixture. They work great.

 

[Kawarthapine]

I wish to support Lance's suggestion of staggering the times for banks of light to simulate low light periods at dawn and dusk.

I started doing that with alternate banks in my grown room and I think the plants like it.

 

[Happypaphy7]

Well, I just downloaded the app you recommended, but it seems to have some defect.

I checked the reading by the window and under the T8 lights.
The reading is crazy high. Then, the app shoots up this prompt saying I have to put a diffuser. So, I did as it directs.
Now the reading is crazy low. Even when I place the phone screen right up against the light, it is barely 1,050 fc. At the plant level, it is from 890 (short plants) to 1,000 tall plants that are about 8-10 inches away from the light.
This cannot be right I thought, then the app says the reading is abnormal and I need to calibrate. It is cloudy so I cannot do it.
It says I have to do it outside when it is sunny.
It is supposed to be rainy for the next few days, so I guess I will have to wait till some time next week.

Did you use white sheet of paper as a diffuser as the app asks to do?
I wonder if it's not white sheet of paper but clear paper as is shown in its demo pages?
I wonder this because when the white paper (I used an envelope), the reading was too low.

I was just in the process of writing this (and planning to point out my 'Collections' thread when you just posted on it!

I was going to suggest that you might have a bit too much light there with 2 x 2 tubes. I'm getting approx. 1200/1250fc at the leaves currently which is 'enough' from what I've read/heard. Leaves are approx 11"-14" from lights. Mine are 5ft 58w Daylight tubes which were swapped out with the warm white tubes which came with the fittings. I plan on changing them every 12 months as they're not expensive.

I've only been running it for a couple of weeks but everything seems very happy thus far.

If you've got an iPhone (maybe Android also has an app); I use an app called GreenThumb which utilises the iPhone camera's light sensor and gives a fc reading. Might be worth a look. It's how I got my reading above.

Regarding photoperiod, mine are currently on for 14 hrs and over the next couple of months, I was planning on raising that by 1 hr each month until June (so 16 hrs) and then starting to back it off by 1 hr a month until it 'winters' at 10 hrs for a couple of months.

What temps/humidity are you getting in there?

 

[Happypaphy7]

Also, the shop lights you have; do they have reflectors on/in them? I was advised that 2 tubes per shelf was enough without reflectors. If you've got 4 tubes per shelf with reflectors.....

Yes and no.
It is not meant for plant growing, so the fixture does have reflector if you can call it, which is painted white.

I have seen my friends T5 set up where the reflector was clear like mirror, which I think reflects a lot more of course.

 

[Happypaphy7]

You can turn off any of the tubes by simply twisting the tube a little...not so much that it falls out, just enough so it looses contact on the power.

For individual timers you can get the cheap ones sold for Christmas lights for about $4, put one on each fixture. They work great.

I would like to try, but it is a bit tricky.
Do you see how Gary's setup has two T8 bulbs, but they allow equal space between the bulbs, and between the bulbs and the end of the shelf?

Mine has two fixtures with two bulbs each.
I guess I could take two out in alternating order, like say if the bulbs are numbered 1 2 3 4 from back to front, I could take 2 and 4, or 1 and 3?
If I were to take out 2 and 3, then the center might not get enough light, and if I took out 1 and 4, then the plants around the edge of the shelf wouldn't get enough light.
hmmm This is a headache.

 

[Happypaphy7]

I wish to support Lance's suggestion of staggering the times for banks of light to simulate low light periods at dawn and dusk.

I started doing that with alternate banks in my grown room and I think the plants like it.

Yes, that would be closer to what they experience in the wild.

 

[Happypaphy7]

Here is another interesting result to consider.
I should post a picture as I don't know the name of this plant, but for now without a picture of it, I have this little plant, which changes its color according to the light intensity.
It stand about only 3-4 inch tall, so it is as short as some really small seedlings in the light stand.

I had this plant by the window before and it was golden green. light green with yellow hue.
It is now just light green without yellow hue, meaning it has less light, and it should be correct because sun, even if filtered through fish net curtain (this allows a lot more light than sheer curtain) is much stronger than light from florescent bulb.

Is there anything in artificial light that might have different impact than sun?

No one seems to mention this, so I'm not sure if the detail in the original posting was all read, but majority of the plants are fine.
Some are even greening up. Hence the topic name, mixed results.
I don't really see anything consistant, and this is crazy!

 

[gonewild]

Is there anything in artificial light that might have different impact than sun?

Definitely yes

 

[gonewild]

The color of the light will make shades of green appear differently to the human eye. That is because what your eye sees as color is actually the color of the reflected light. So maybe what you see as a slight color shade change in the leaves is actually the change in source light color and not a change in color of the leaf when moved from one light source to another.

There is at least a half dozen different colors of "white" fluorescent available it the T8 tubes. Each one will make the leaves look a different shade of green immediately when the plant is placed under it. And each different color of fluorescent will cause the plant to grow differently. You may or may not see a physical difference but there is a difference.