Greenhouses forum: lighting in my two greenhouses

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Name: Ken Ramsey
Starkville, MS (Zone 8a)
[url=www.tropicalplantsandmore.com]
Orchids Greenhouse Vegetable Grower Ferns Region: United States of America Hummingbirder
Composter Bromeliad Master Gardener: Mississippi Cat Lover Tropicals Plumerias
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drdawg
Dec 13, 2015 10:33 AM CST
I know this picture won't be of much value since I can't compare the lighting with that of T-12, T-8, or T-5, but it will perhaps give you some idea of the brightness that T-5HO fixtures produce. You are seeing the light transmitted not only through polycarbonate but also 16 mil solar blanket material. Also, in the greenhouse on the left, the right side is illuminated by T-5 fixtures and the left side is illuminated by T-5HO fixtures, two fixtures on each side. My more light-sensitive plants are positioned under those standard T-5 fixtures.

Click on the picture to see both greenhouses.

Thumb of 2015-12-13/drdawg/39c29c

drdawg (Ken Ramsey) - Tropical Plants & More
[url=www.tropicalplantsandmore.com]www.tropicalplantsandmore.com[/url]
If God wanted me to touch my toes, he would have put them on my knees.
Name: Rick Corey
Everett WA 98204 (Zone 8a)
Sunset Zone 5. Koppen Csb. Eco 2f
I helped beta test the first seed swap Plant and/or Seed Trader Seed Starter Region: Pacific Northwest Photo Contest Winner: 2014 Vegetable Grower
Avid Green Pages Reviewer Garden Ideas: Master Level Garden Sages I was one of the first 300 contributors to the plant database! I helped plan and beta test the plant database. Charter ATP Member
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RickCorey
Dec 18, 2015 3:53 PM CST
I just replaced an old 48 Watt, 48", two-tube T12 fixture in my kitchen with a new 32-Watt, 48", two-tube T8 fixture. They weren't even 42 Watt T8s.

T8 instead of T12, but using 33% less power.

That new light is BRIGHT!! I mean, the cat scrunches up his eyelids and then glares at me as he stalks out of the kitchen when I turn it on.

I mean, I almost think about wearing sunglasses, and sometimes I flinch.

Maybe choosing "cool blue" tubes added to the shock. The old tubes were "warm" color and many years old, so the tubes and ballast were on their last legs. Whatever it was, it feels like 2-3 times as much light.
Name: Ken Ramsey
Starkville, MS (Zone 8a)
[url=www.tropicalplantsandmore.com]
Orchids Greenhouse Vegetable Grower Ferns Region: United States of America Hummingbirder
Composter Bromeliad Master Gardener: Mississippi Cat Lover Tropicals Plumerias
Image
drdawg
Dec 18, 2015 4:16 PM CST
Rick, I think you will find that the same length T-5 fixtures will be even more economical and brighter. The T-5HO WILL require sunglasses. Whistling
drdawg (Ken Ramsey) - Tropical Plants & More
[url=www.tropicalplantsandmore.com]www.tropicalplantsandmore.com[/url]
If God wanted me to touch my toes, he would have put them on my knees.
Name: Rick Corey
Everett WA 98204 (Zone 8a)
Sunset Zone 5. Koppen Csb. Eco 2f
I helped beta test the first seed swap Plant and/or Seed Trader Seed Starter Region: Pacific Northwest Photo Contest Winner: 2014 Vegetable Grower
Avid Green Pages Reviewer Garden Ideas: Master Level Garden Sages I was one of the first 300 contributors to the plant database! I helped plan and beta test the plant database. Charter ATP Member
Image
RickCorey
Dec 18, 2015 4:46 PM CST
blink-blink-blink

I wish I had had T5 bulbs years ago when I grew some plants indoors!
Name: Ken Ramsey
Starkville, MS (Zone 8a)
[url=www.tropicalplantsandmore.com]
Orchids Greenhouse Vegetable Grower Ferns Region: United States of America Hummingbirder
Composter Bromeliad Master Gardener: Mississippi Cat Lover Tropicals Plumerias
Image
drdawg
Dec 18, 2015 4:57 PM CST
Thumbs up
drdawg (Ken Ramsey) - Tropical Plants & More
[url=www.tropicalplantsandmore.com]www.tropicalplantsandmore.com[/url]
If God wanted me to touch my toes, he would have put them on my knees.
Name: Carol Texas
Central Texas (Zone 8b)
"Not all who wander are lost."
Region: Texas Composter Greenhouse Cactus and Succulents Organic Gardener Hummingbirder
Herbs Garden Art Dragonflies Garden Ideas: Level 2
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Ecscuba
Jan 13, 2016 10:17 AM CST
I've been reworking the lighting in my GH since my seedlings are too scrawny and feedback (on this site as well as from Rare Seeds/Baker Creek indicates I likely don't have enough light). So I purchased some T5 tube fixtures and bulbs. I still have 6 clip on lights with CFL . However, there is such conflicting information on the web about whether lumens is important. One very detailed site talked about the need for 3,000 lumens per sq. ft - that was an article on growing marijuana (which is not in my GH), but it's a green plant. Other sites say lumens are not important - only K rating. My new T8 tube fixtures will each have two 6500 K bulbs at 2900 lumens each - My intent was to put that over a 18" x 3' shelf - and I had hoped that would be enough light - but maybe it won't. Maybe I'll have to put both fixtures over one shelf and buy two more for the next shelf over ?
[url=Www.carolmedfordart.com]Www.carolmedfordart.com[/url]
My passion is painting but gardening is running a close second.
Name: Ken Ramsey
Starkville, MS (Zone 8a)
[url=www.tropicalplantsandmore.com]
Orchids Greenhouse Vegetable Grower Ferns Region: United States of America Hummingbirder
Composter Bromeliad Master Gardener: Mississippi Cat Lover Tropicals Plumerias
Image
drdawg
Jan 13, 2016 11:07 AM CST
Both lumens and Kelvin are important but for different reasons. The amount of brightness (lumens) is going to be more important though. Without adequate brightness, it really doesn't matter what the Kelvin (range of light, from yellow/amber to blue/purple). I published two articles on Light in January/February, 2014, and these articles may be of some help. The 6500K fluorescent tubes will produce more lumens than the 4500K tubes.

I am a little bit confused. You say you just purchased T5 fixtures but then say that you are using T8 fixtures. I prefer the T5 fixtures because you'll get more lumens from those. The Kelvin will be the same from either T8 or T5. 6500K is great for plant growth/greening. The 4500K stimulates flowering. If you are using the T8 fixtures, they should be adequate supplemental light for a single shelf. Just remember that you'll lose lumens very rapidly as the plants are positioned further away from the fixtures. Thus, you'll want the tubes as close as reasonably possible to your plants. I haven't used T8 fixtures in quite a few years, but I had my orchids within 6" of those tubes, probably more like 3" away. If you are using T5 fixtures, you'll be able to get more lumens at the plant-level than with the T8. I now use T5 HO fixtures and I have to position my orchids at least 24" from those fixtures. These fixtures produce huge amounts of lumens (30,000, 1" from the tubes!) and get hot as well. These fixtures that I now use are 4'x6tubes.
drdawg (Ken Ramsey) - Tropical Plants & More
[url=www.tropicalplantsandmore.com]www.tropicalplantsandmore.com[/url]
If God wanted me to touch my toes, he would have put them on my knees.
Name: Carol Texas
Central Texas (Zone 8b)
"Not all who wander are lost."
Region: Texas Composter Greenhouse Cactus and Succulents Organic Gardener Hummingbirder
Herbs Garden Art Dragonflies Garden Ideas: Level 2
Image
Ecscuba
Jan 13, 2016 2:09 PM CST
@drdawg very helpful. Thank you. I meant to say I purchased T8 - not T5. Great - I'm hanging the lights this afternoon (well, "Mr. Ed" actually is .. haha - he's building a support around both of the shelving units and hanging the T8 lights from them) Thank You! I tip my hat to you. . I'll watch closely and make sure the plants don't cook. I think I've had inadequate light both last year and this year - so hopefully this will make a big improvement in my yield. I am growing only greens (no flowers) - lettuce, kale, pak choy, etc. We'll see how it goes. Thanks for the input and I'll look up both of your articles.
[url=Www.carolmedfordart.com]Www.carolmedfordart.com[/url]
My passion is painting but gardening is running a close second.
Name: Ken Ramsey
Starkville, MS (Zone 8a)
[url=www.tropicalplantsandmore.com]
Orchids Greenhouse Vegetable Grower Ferns Region: United States of America Hummingbirder
Composter Bromeliad Master Gardener: Mississippi Cat Lover Tropicals Plumerias
Image
drdawg
Jan 13, 2016 2:13 PM CST
Carol, if I remember correctly, T8 lights produce very minimal heat. That should not be a problem at all. The 6500K should be right for what you are growing.
drdawg (Ken Ramsey) - Tropical Plants & More
[url=www.tropicalplantsandmore.com]www.tropicalplantsandmore.com[/url]
If God wanted me to touch my toes, he would have put them on my knees.

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