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Grow Light Information

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published by SleestaksRule on Sun, 12/04/2011 - 07:12
 
 

Grow Light Compare

Grow Light Comparison Chart

Grow Light Used  

   Watts

Growing Area

Heat Output

Recommended Light Height Above Plants

Bulb Life
(hours)

Primary

Secondary

Incandescent

150

0.5' x 0.5'

1' x 1'

Medium

1' to 2'

2,000

CFL

40

1' x 1'

2' x 2'

Very Low

3" to 1.5'

10,000

CFL

125

2' x 2'

3' x 3'

Low

6" to 2'

10,000

CFL

200

2.5' x 2.5'

4' x 4'

Low

6" to 2'

10,000

2' T5 (single)

24

1' x 2'

1.5' x 2.5'

Very Low

3" to 2'

20,000

2' T5 (2 bulbs)

48

1.5' x 2.5'

2' x 3'

Very Low

3" to 2'

20,000

2' T5 (4 bulbs)

96

2' x 3'

3' x 4'

Low

6" to 2'

20,000

4' T5 (single)

54

1' x 4'

1.5' x 5'

Very Low

3" to 2'

20,000

4' T5 (4 bulbs)

216

2.5' x 5'

4' x 6'

Low

6" to 3'

20,000

4' T5 (8 bulbs)

432

4' x 6'

6' x 7'

Low

1' to 3'

20,000

HPS

250

3' x 3'

5' x 5'

Medium

2' to 3'

24,000

HPS

400

5' x 5'

8' x 8'

High

3' to 4'

24,000

HPS

600

6' x 6'

10' x 10'

High

3' to 4'

24,000

HPS

1000

8' x 8'

12' x 12'

Very High

4' to 6'

24,000

MH

250

3' x 3'

5' x 5'

Medium

2' to 3'

10,000

MH

400

5' x 5'

8' x 8'

High

3' to 4'

10,000

MH

1000

8' x 8'

12' x 12'

Very High

4' to 6'

10,000

 

Growing Area
The growing areas listed above assume the light bulbs are being used in a fixture
with a reflector.
Primary - Use the area in this column if the grow light will be the main or only source of light for the plants. This includes areas where minimal light comes Property of littlegreenhouse.comfrom windows or standard house/office lights.
Secondary - Use the area in this column if the grow light will be used in a greenhouse or other area that receives direct sunlight for part of the day to supplement the light from the sun.

 

Heat Output
The chart above uses a combination of the light bulb temperature and the dimensions of the bulb(s).

Bulb

Average Bulb Temperature

.

Bulb

Average Bulb Temperature

T5

100 to 120° F

Incandescent

220 to 260° F

CFL

130 to 180° F

MH/HPS

450 to 550° F
 

How Long Should Grow Lights Run?
This depends on the type of plant. Foliage plants need about 14-16 hours of light per day. Flowering plants need 12-16 hours of light per day. You should give most plants at least 8 hours of total darkness daily. Try to have the lights on at the same time every day. You can get an automatic timer for your lights to make it easier.
 

The Electrical Cost to Run a Grow Light System

To get the operating cost per hour for a light, take the lights combined wattage, and divide it by 1000 to get the kilowatts used. Then multiply that number by the amount your electric company charges per kilowatt hour. HID lights will use the number of watts it emits per hour, ie; 600w system will use 600 watts per hour (regardless of spectrum).
(light wattage output / 1000) x electricity cost per kilowatt hour = Operating cost per hour
operating cost per hour x hours used per month = Operating cost per month

 

Comments

Submitted by rlattajr on Sat, 04/27/2013 - 09:46.

I found warehouse lights on craigslist, 1000w and 400w.

I have read that high pressure sodium bulbs are more efficient than metal halide bulbs.  Which would grow the best?

When we get frost warnings here in Florida and a temp drop I would roll my vertical aeroponic towers in the garage and grow.  The lamps would also provide heat.

 

Robert

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Submitted by SleestaksRule on Sat, 04/27/2013 - 12:47.

I use 400 watt metal halide and use a conversion bulb to run high pressure sodium.  I use the metal halide for the veg growth until I get flowers then switch it to the HPS.  I really don't notice a difference in growth between the 2 but I do it anyway. 

Right now I'm using the metal halides for getting my plants going for outdoors.  I have my fluorescent lights all in use starting other plants and needed more light.  I have them about 2' above the plants.  Just took the photo below.  Tomatoes and Virginia Gold Tobacco, devil

Seedlings under metal halide

Submitted by xxnasmaxx on Wed, 05/15/2013 - 14:02.

saw your video on building grow light using dryer pipe, what cfl light do you recommend that i can pickup at a hardware store. i need one that will work for tomatoes, peppers, carrots, rasishs and cucumber, and different herbs.

thanks in advance. im new to this. and wanna grow vegatables all year long in basement.

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Submitted by SleestaksRule on Wed, 05/15/2013 - 15:27.

Here's the one I use for small tomato plants, radish, lettuce, peppers, haven't tried carrots.  It works great as long as the plant doesn't get too tall. 

Here's the bulb on Amazon: BULB LINK

You can get it at local big box hardware stores for about $9 per bulb (get 2).

Radishes in 25 days from seed under those guaranteed.

Submitted by xxnasmaxx on Wed, 05/15/2013 - 17:22.

Will that bulb work for both veging and flowering stages? And the tomatoes seeds I'm using are beefsteak.

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Submitted by SleestaksRule on Thu, 05/16/2013 - 07:40.

Beefstake will get 6' tall and then some.  You'll need a powerful light like a metal halide or high pressure sodium to get enough light for the entire plant.  I wouldn't grow anything much bigger than a pepper plant under a cfl.  Tiny Tim tomatoes do great under them.  Home Depot carried a 68 watt 2700k cfl bulb that was pretty cheap a few years ago and I used that for the flower stage.  I'm not sure if they still have it but I'm still using mine.

Submitted by xxnasmaxx on Thu, 05/16/2013 - 09:25.

sorry double posted

Submitted by xxnasmaxx on Thu, 05/16/2013 - 09:22.

ok, so from what im understanding ill be using a 6500k bulb for veging, and once plant starts to flower ill switch the bulbs out to a 2700k? and the higher the watts the better?

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Submitted by SleestaksRule on Thu, 05/16/2013 - 09:26.

Right.  I just grew red robin  tomatoes under 2 42 watt CFL at 6500k throughout the whole grow without switching to 2700K and they still did great.  The higher watts will give you more light so that the light will reach the lower leaves better.

Submitted by xxnasmaxx on Sun, 05/19/2013 - 12:17.

Can I use a 5000k bulb instead of 6500?

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Submitted by SleestaksRule on Sun, 05/19/2013 - 13:54.

The 5000k bulb will work just fine.  6500k is just the ideal for veg growth.

Submitted by xxnasmaxx on Sun, 05/19/2013 - 12:34.

How are these???

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Submitted by SleestaksRule on Sun, 05/19/2013 - 13:55.

Got a link?

Submitted by xxnasmaxx on Sun, 05/19/2013 - 14:28.

http://s9.postimg.org/819q883j3/image.jpg

they have them in both 2700k and 5000k

​only prob is there 3 way bulbs

Submitted by xxnasmaxx on Sun, 05/19/2013 - 13:09.

Also eats ur thought on using 40w t12 for growing veggies in basement

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Submitted by SleestaksRule on Sun, 05/19/2013 - 13:58.

You could probably get away with growing lettuce with a T12 is you keep it as close as possible to the plants.   Anything like tomatoes and peppers will get leggy and not grow good at all.  I use them just for starting seeds.

Submitted by xxnasmaxx on Sun, 05/19/2013 - 23:35.

Also should I power each socket individually? Or will light output be the same.

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Submitted by SleestaksRule on Tue, 05/21/2013 - 09:27.

The light output would be the same.

Submitted by xxnasmaxx on Thu, 05/30/2013 - 20:57.

Got another question. What are your thought on mixing 2700k and 6500k bulbs?I wanna build a few fixtures that will be used to grow both leafy plants and tomatoes pepper and other veggies, in those fixtures I will be using 2-4 200 watt 2700k bulbs and 2-4 200 watt 6500k. Will this cause issues? My hopes are to match solar light as close as possible. I'm assuming this will be more beneficial to all plants I'm growing? So far my tomatoe plant I'm growing is doing well. Many flowers and 14 tomatoes already under two 200 watt  2700k bulbs.

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