Artificial Lighting - Orchid Board

Becca · #1 06-19-2007, 05:00 PM

I have a plant table that came with built in grow lights. I had to write to the manufacture to find out what kind they were and this is what I was told: "There are 2 different bulbs in the fixture, a 10,000K white light bulb which promotes green leaf growth and a special blue/pink bulb to promote plant flowering. Both bulbs are fluorescent T4 bulbs." I was also told that replacement bulbs could be purchased through the same company at a price of $8.00 for the 10,000k bulb and $10.00 for the other bulb. My questions:

1. What is the difference between a T4 and a T5 bulb?
2. What is the life of a T4 bulb?
3.Is there something better and if so why?
4. Are these normal prices for this type of bulb?

TIA!

P.S....and don't I need to know the wattage and how do I find this?

Ross · #2 06-19-2007, 06:44 PM

Never heard of T4. As far as I know, there are 3 basic florescent bulb types. T5, T8 and T12. The T12 are shop lights seen in basic florescent fixtures. The T8 are the newer thinner bulbs, becomming more common as they tend to be a bit brighter. The T5 are the super bulbs with approx 5000 lumens at the bulb surface. I wonder if they are trying a fast one on you?

Doubt the specs the manufacturer states. 10,000K is REALLY blue! I mean REALLLYYY blue! I mostly see blue bulbs in the 6000-7000K range which is blue light like full shade. Full sun at the equator is approx 5500K. (K stands for Kelvin, which is a standard measure of light 'temperature'). So a normal mix of "reddish" bulbs (which promote flower gowth) to "blueish bulbs" (which promote vegetative growth) is typically 1:3 (based on the order I listed them.) Most growers just use standard "daylight" florescent tubes and don't quibble about light temps. I am using 3 6000K tubes and 1 3500K tube in my T5 light bank and all seems VERY well with this mix.

Ross · #3 06-19-2007, 06:47 PM

Oh, as for life, you "should" get at least a full year based on 12-14 hours "on" cycle for best quality T5 bulbs. Yes the price seems about right for replacement. If, in fact, they are T5 bulbs, you can get those at any hydroponics store.

Becca · #4 06-19-2007, 06:52 PM

Well I did a search on T4 bulbs and found them for sale, but not really much info, maybe I just missed something. Anyways, so the higher the k number such as 10,000k is more blue, and more blue means light that is similar or like shade? I just wanted to make sure I understood that correctly, it is kind of confusing. I have a bunch of seedlings under these two lamps, such as dendrobiums, and catts and they all have new growths that are taking off like crazy. I thought they needed more light, wouldn't a blue lamp like this which imitates shade lighting not be great for them? I will have to measure my bulbs and see what I can replace them with. Perhaps I should email the manufacture of the table again and get some better specs since these lights came with the table! I hope they didn't do something wacky like make it so only certain bulbs will fit into the fixture making so I have to buy the lights from them!

Ross · #5 06-19-2007, 07:05 PM

Quote:

Originally Posted by RPfeiffer

Well I did a search on T4 bulbs and found them for sale, but not really much info, maybe I just missed something. Anyways, so the higher the k number such as 10,000k is more blue, and more blue means light that is similar or like shade? I just wanted to make sure I understood that correctly, it is kind of confusing. I have a bunch of seedlings under these two lamps, such as dendrobiums, and catts and they all have new growths that are taking off like crazy. I thought they needed more light, wouldn't a blue lamp like this which imitates shade lighting not be great for them? I will have to measure my bulbs and see what I can replace them with. Perhaps I should email the manufacture of the table again and get some better specs since these lights came with the table! I hope they didn't do something wacky like make it so only certain bulbs will fit into the fixture making so I have to buy the lights from them!

I think you are freaking out

You are right, the higher the K number the bluer the light. For growth, that is academic. But for continued health of the plants (I am presuming you want to continue long-term care for these plants) then average K of the light you provide is the most important thing. This means you need to be able to provide what the plants want and need over the whole season without complicated regimes of changing bulbs, etc. That's why most growers just opt for "daylight" bulbs. Since you have invested in this system I would recommend two things: #1 is try to find out what the heck a T4 bulb is. If they mean T5 then you are good to go. #2 is to try to not worry so much about the light and watch the plants. If you aren't getting blossoms or spikes when you know full-well you should be, then switch the hi-K bulb for a lo-K bulb for a while and see if that doesn't make a change. The lumens should stay consistent - only the color temperature (kelvin) will change, between bulbs.

Ross · #6 06-19-2007, 07:13 PM

I just re-read my response and realize I really may have confused things. The bluer the light (higher K ratings) the plants respond with plant growth only. The reder the light (lower K values), the more likely that plants will respond with flower production. Think about it. This is related to sun position in the horizon. Doesn't matter southern or northern hemisphere - only months of the year. So if sun is low in horizon for a significant time of the year, it signifies spring or fall. During this time, the sun has to go through the fullest amount of atmosphere and is "reddish" or warm (thus the low K bulb.) During the summer, the sun is at it's highest setting, and closest to 5500K, and this relates to the highest K bulbs. If you now find out when your orchids typically bloom, then you start to zero in on the best combination of lights to cause the event to occur!

Becca · #7 06-19-2007, 07:15 PM

I am good at freaking out

I requested some more info from the manufacture of the table, since they came with it. The plants are seedlings and are far far away from blooming. As long as they are growing I am happy, in a few years when they are near blooming size, I will hopefully have a green house and I will worry about proper humidity levels and light levels then unless I have some problems along the way. I was just curious mostly about the difference of the T4 and T5 bulbs since I saw another post on here about T5 bulbs. Thank you for your help!

Becca · #8 06-19-2007, 07:21 PM

well the fixture has the blue bulb (the 10,000k), and then a special blue/pink bulb so maybe I have a decent balance of both lighting!

Ross · #9 06-19-2007, 07:25 PM

Quote:

Originally Posted by RPfeiffer

well the fixture has the blue bulb (the 10,000k), and then a special blue/pink bulb so maybe I have a decent balance of both lighting!

I would assume so. So now on to humidity

Becca · #10 06-21-2007, 01:47 PM

Quote:

Originally Posted by RPfeiffer

....There are 2 different bulbs in the fixture, a 10,000K white light bulb which promotes green leaf growth and a special blue/pink bulb to promote plant flowering. Both bulbs are fluorescent T4 bulbs.

Ross, I looked at my bulbs last night and they are stamped as described by the manufacture of the plant table. They are both 18w bulbs as well. I wasn't given a "brand" name, but the bulbs also have the website of the plant table manufacture stamped on them as well. I thought that was interesting so I thought I would pass the info along. I think the company must be making their own "special" grow lights for their products. The only think I found on T4 bulbs when searching on google is that they are used for under-cabinet lighting? So maybe they are trying to get some grow lights on the market in the T4 size? Since my bulbs are a T4, does this mean my fixture probably won't hold a T5? I am assuming so. Thanks!