Is this fluorescent light ok?

robertoccm · February 3, 2013

Hey everyone, I just want to ask you if this bulb is ok for growing plants indoors:+

- F15T8
- 18 inch long bulb
- Light output: 940 lumens
- 15 watts
- 3000 k
- 70 cri

It says it is for use in kitchens and baths but I just want to know it it will also work for plants.

paulgrow · February 3, 2013

I prefer to use a 40 watt

Hotwired · February 3, 2013

I'm assuming that you are wanting to start plants inside for planting out and won't be flowering. The 3000K is primarily red light in the 600-700nm wavelength range. 6500K is primarily Blue Light which is used for Foliage Growth, while Red light such as your bulb is used by the plant primarily for flowering. Here's a spectral curve of a 2800K warm white bulb with is similar to yours http://imageshack.us/a/img543/3018/w...tecflcurve.jpg . I would suggest that you pick up a 6500K bulb or a daylight bulb http://imageshack.us/a/img560/3693/daylightcflcurve.jpg .

robertoccm · February 3, 2013

thanks everyone, do lumens matter?

Dak · February 4, 2013

Hotwired, thank you for your clear explanations here on the forum regarding lighting. I've taken your advice, my seedlings are under 65K lights and are growing like weeds. No need for expensive grow lights, daylight fluorescent lights work great.

FlyingZ · February 4, 2013

Yeah, I have never understood why some people insist on paying so much for "grow bulbs" in fluorescent lights. I also use the T-8 6500K bulbs and have grown lettuce to full term and also tomatoes to about 12". Also, lumens do matter, the more the better (within reason)

robertoccm · February 4, 2013

So I guess an 18'' long, 6500k, 700 lumens, 15 watts and 75 cri is ok?

gixxerific · February 4, 2013

Please listen to Hotwired he knows what He is talking about. Me. you can listen to me too but but I am not as advanced.

I prefer the T5's they seem to work much better. I have everything from T-12 to T-5 even T-5 HO. The T-5 HO are the bomb are they neccesary it depends on what you are doing. For lettuce and other leafy green plants anything will do but make it 6500K. If growing plants to fruition like tomatoes you need as much light as you can get. You will also need more of the 28K - 32 'ish K region in there as well. I beleive Hotwired and myself both like a 1-4 ratio. One 28K - 32K to three 6500K.

Yes lumens do matter. More lumens more light.

The CRI is also a factor but that is more of a high end parameter.

Way too much to go into in one post.

Rockporter · February 5, 2013

I have been doing a lot of research on lighting to determine what I wanted to purchase and I went with a 20,000 lumens light fixture. What I learned was about 5,000 lumens per square foot would be the best because it is similar to what the sun provides. The seedlings will have good strong roots and the stocks will be thick as well since they are not reaching for light.

The light fixture I went with http://www.htgsupply.com/Product-HTG...5-Tek-Lamp.asp is expensive but it provides 20,000 lumens in a 24"x24" fixture.

They have taken a 5,000 lumens 4' bulb and made it into a 2' bulb providing the same light output as the 4' bulb. http://www.htgsupply.com/Product-Gro...e-of-Bulbs.asp

I am getting 20,000 lumens in a smaller space which will cover what I need and allow me to grow into the flowering stage anything I want to grow indoors in the heat of summer. This is why I chose to go this route. I'm thinking dwarf tomato and lettuce.

If all you want to do is start seedlings for later plant out in the garden you could go with a 10,000 lumen fixture http://www.htgsupply.com/Product-HTG...5-Tek-Lamp.asp# which is also only 24"x12" and only $69.00

I can get two 72 count seedling trays under a 24"x24" light leaving plenty of light for all the seedlings at the initial germination stage. When the light is lifted it will cover more area, the rep at HTG told me it should cover at least a 3'x3' area or more.

If you do go the same route and use the light fixture I have just mentioned here I suggest you make sure to purchase extra bulbs at the time of order because they have a discount if ordered at the same time. The PL55 bulbs are not available in stores so I ordered four extra grow bulbs and a full set of four flowering bulbs.

Also, the Hi-Lo fixture hanger is a good idea too, you can easily lift the light out of the way when you are working on your trays.

Good luck with your choice and welcome to Tomatoville.

February 3, 2013	#1
robertoccm Tomatovillian™ Join Date: Jul 2012 Location: Mexico Posts: 80	Is this fluorescent light ok? Hey everyone, I just want to ask you if this bulb is ok for growing plants indoors:+ - F15T8 - 18 inch long bulb - Light output: 940 lumens - 15 watts - 3000 k - 70 cri It says it is for use in kitchens and baths but I just want to know it it will also work for plants.

February 3, 2013	#2
paulgrow Tomatovillian™ Join Date: Jan 2011 Location: Allen Park, MI Posts: 178	I prefer to use a 40 watt __________________ A world without tomatoes is like a string quartet without violins. ~Author Unknown~

February 3, 2013	#3
Hotwired Tomatovillian™ Join Date: Nov 2012 Location: Ithaca, NY - USDA 5b Posts: 241	I'm assuming that you are wanting to start plants inside for planting out and won't be flowering. The 3000K is primarily red light in the 600-700nm wavelength range. 6500K is primarily Blue Light which is used for Foliage Growth, while Red light such as your bulb is used by the plant primarily for flowering. Here's a spectral curve of a 2800K warm white bulb with is similar to yours http://imageshack.us/a/img543/3018/w...tecflcurve.jpg . I would suggest that you pick up a 6500K bulb or a daylight bulb http://imageshack.us/a/img560/3693/daylightcflcurve.jpg . __________________ Give a man a fish and he eats for a day - Teach him to fish and he eats for a lifetime.

February 5, 2013	#9
Rockporter Tomatovillian™ Join Date: Feb 2012 Location: Texas Coastal Bend Posts: 3,205	I have been doing a lot of research on lighting to determine what I wanted to purchase and I went with a 20,000 lumens light fixture. What I learned was about 5,000 lumens per square foot would be the best because it is similar to what the sun provides. The seedlings will have good strong roots and the stocks will be thick as well since they are not reaching for light. The light fixture I went with http://www.htgsupply.com/Product-HTG...5-Tek-Lamp.asp is expensive but it provides 20,000 lumens in a 24"x24" fixture. They have taken a 5,000 lumens 4' bulb and made it into a 2' bulb providing the same light output as the 4' bulb. http://www.htgsupply.com/Product-Gro...e-of-Bulbs.asp I am getting 20,000 lumens in a smaller space which will cover what I need and allow me to grow into the flowering stage anything I want to grow indoors in the heat of summer. This is why I chose to go this route. I'm thinking dwarf tomato and lettuce. If all you want to do is start seedlings for later plant out in the garden you could go with a 10,000 lumen fixture http://www.htgsupply.com/Product-HTG...5-Tek-Lamp.asp# which is also only 24"x12" and only $69.00 I can get two 72 count seedling trays under a 24"x24" light leaving plenty of light for all the seedlings at the initial germination stage. When the light is lifted it will cover more area, the rep at HTG told me it should cover at least a 3'x3' area or more. If you do go the same route and use the light fixture I have just mentioned here I suggest you make sure to purchase extra bulbs at the time of order because they have a discount if ordered at the same time. The PL55 bulbs are not available in stores so I ordered four extra grow bulbs and a full set of four flowering bulbs. Also, the Hi-Lo fixture hanger is a good idea too, you can easily lift the light out of the way when you are working on your trays. Good luck with your choice and welcome to Tomatoville. __________________ In the spring at the end of the day you should smell like dirt ~Margaret Atwood~

February 4, 2013	#5
Dak Tomatovillian™ Join Date: Mar 2009 Location: CA Posts: 494	Hotwired, thank you for your clear explanations here on the forum regarding lighting. I've taken your advice, my seedlings are under 65K lights and are growing like weeds. No need for expensive grow lights, daylight fluorescent lights work great.

February 4, 2013	#6
FlyingZ Tomatovillian™ Join Date: Sep 2011 Location: Pittsboro, NC Posts: 21	Yeah, I have never understood why some people insist on paying so much for "grow bulbs" in fluorescent lights. I also use the T-8 6500K bulbs and have grown lettuce to full term and also tomatoes to about 12". Also, lumens do matter, the more the better (within reason)

February 4, 2013	#8
gixxerific Tomatovillian™ Join Date: Jul 2011 Location: in the gutter, with my mouth Posts: 123	Please listen to Hotwired he knows what He is talking about. Me. you can listen to me too but but I am not as advanced. I prefer the T5's they seem to work much better. I have everything from T-12 to T-5 even T-5 HO. The T-5 HO are the bomb are they neccesary it depends on what you are doing. For lettuce and other leafy green plants anything will do but make it 6500K. If growing plants to fruition like tomatoes you need as much light as you can get. You will also need more of the 28K - 32 'ish K region in there as well. I beleive Hotwired and myself both like a 1-4 ratio. One 28K - 32K to three 6500K. Yes lumens do matter. More lumens more light. The CRI is also a factor but that is more of a high end parameter. Way too much to go into in one post.