42w

How many of these are good enough for growing in a 3ft x 2ft cardboard box.
For one plant.

Or any better cfl suggestions?

I'm using emergency blankets for reflection.

From Ed Rosenthal:

In the new Skunk Magazine there was a question in the "Ask Ed" section that just made my night last night when reading it...



The question was:

I intend to grow a single cannabis plant in a space 1' x 2'. What light would you recommend? I was think of using four 30-watt compact fluorescent lamps. Will this be enough? Cost isn't an issue but I am deterred from getting a high pressure sodium [light] because of the amount of heat the bulb produces.

Answer:

As you mentioned, you have several lighting systems to choose from, including compact fluorescents and high pressure sodium (HPS) lamps. Among HPS lamps you have a choice between a single 100-watt lamp which uses a total of about 120-watts and emits about 8,800 lumens(73 lumens per watt) or a 150-watt lamp, which uses about 180 watts and emits almost double that-15,800 lumens (87 lumens per watt).

A 42-watt compact fluorescent (CFL) emits about 2700 lumens(64 lumens per watt). Four 42 watt CFLs use 168 watts and emit 10,800 lumens. Other size CFLs have a similar efficiency.

However, that is only part of the story. Plants use mostly red and blue light. Yellow and green light is of little use to them, so light that is emitted in these spectrums is wasted energy. Most of the light emitted by HPS lamps is in the yellow spectrum. Only a small amount of the emitted light is is in the orange or red spectrums, which plants use efficiently. Warm white fluorescents (2700 Kelvin) emit a greater portion in the red and orange sectors.
Although fluorescents produce only about 75% of the light per watt that the HPS does, the amount of light usable by the plant is equal or probably higher with the fluorescents. You may wish to experiment to see if adding a single cool white CFL to replace one warm white results in shorter, stouter stems and more vigorous growth. The reasoning is that warm whites don't emit much blue light, which the plants use for photosynthesis and to regulate their growth. The cool white bulb supplies the blue light.

My call for your unit would be to use several (three to five) CFLs with a total input of between 120-160 watts. Although the 150 watt HPS is a bit more efficient that the CFLs in total output, watt for watt the fluorescents provide as much useful light as the HPS lamp. Heat is another consideration. The HPS runs much hotter and emits more heat than the fluoescents.

Make sure to use reflective material around the garden so that any light escaping the garden is reflected back to the plants. Any light that doesn't get to the plant leaves is wasted.


Look at a lumen/watt ration of various CFL's. The higher the wattage of CFLs, the lower the lumen/watt ratio. This chart was submitted by Jerry Garcia, of RIU and edited for typos.

For example...

the 200w listed at 9250 lumens for a lumens/watt ratio of 9250/200=46.25

the 150w is listed at 7500 lumens for a l/w ratio of 7500/150=50

the 125w is listed at 6500 lumens for a l/w ratio of 6500/125=52

the 42w are listed for 2700 lumens, l/w ratio of 2700/42=64.28

I have some 26w that give off 1700 lumens for a l/w ratio of 1700/26=65.38

GE lists some 13w that give off 825 lumens for a l/w ratio of 825/13=63.46

So, according to these numbers the most efficient bulbs for growing are the 26w that emit 1700 lumens. If you used 8 26w bulbs (208 watts total) you'd be getting 13,600 lumens...4,350 more lumens than a single 200 watt cfl.

I suppose you need to purchase more sockets and cords and things to support 8 bulbs, but in the long run more lower watt CFLs seem like the way to go.

Lets look at some CFLs, these are the Spiral Type bulbs:

42 watt average $ 9 to $10.00 each

65 watts, = $19.99 average price ($16.95 now at Lowes and Home Depot)

85 Watt, average $29.00 each, can be found for $24.95 on Internet

This is a Tube Type bulb, not a spiral bulb. 105 watt bulbs average $34.95 to $38.99 each. 105s come in Tube type and Spiral. Note Tube Types do not work well in Clamp Refectors and an Extension Socket will be needed.

CFLs come in 15, 26, 42, 65, 68, 85 and 105 watts and recently last year, even larger 200, 250 and 300 wattages.
The 26s and smaller are not as efficient to me.
26s to 85s do not put out any noticable heat unless you use dozens of them. The 105s do put out some heat, but not as much as HID lights.
I can touch and hold a burning 65 or 85 watt bulb.
The 42's are about $9 to $10 each.
65 watts are abut $17 to $20 each, 85s are $30 each, 105s are $39 to $42 each, average is $40+ each for 105s.
A CFL needs a reflector, like a hood. I like the $12 Heavy Duty Clamp reflectors at Lowes, or Home Depot. Walmart sells a cheaper $8 reflector but it is smaller and flimsey and does not last. The plastic breaks easily.


DUAL SPECTRUM
With CFLs, you need the DUAL SPECTRUM, red and blue spectrums. That does not refer to the color of the bulb that you see. It refers to the kind of rays, like UVA or UVB, or the color temp of the bulb, called kelvins.
CFLS come in 2700 kevins, 3000, 4100, 5100, and 6500.
Low Kelvin bulbs, like the 2700k is for BLOOM OR FLOWERING, 6500k is for the VEG Spectrum. The others are "MID" spectrums or in between.
IF you use the MID-range bulbs (4100) then also use the 6500 and 2700s for a balanced spectrum.
In outdoors, the sun produces different rays in the spring (VEG Rays called Blue) and late summer rays for the Bloom spectrum, the RED spectrum. The sun also produces green, and orange rays, but plants do not use them.

CFLs are new on the scene, in 2006 the biggest made was 65 watts. When we talk about CFL watts, we are talking about the actually electricity used, NOT the equivalent . For example, a 15 watt CFL bulb puts out 60 watts equvalent .

Spiral and Tube type CLFS emit LIGHT FROM THE SIDES, NOT THE ENDS OR TIPS. Spirals do project light in a circle more than the tube type.

YOU CAN GET SPIRAL CFLS (15, 26, 42, 65, 85) AND TUBE TYPE CFLS (105, 250, 300).

How much light is needed for growing?
Depends on the size of plant you are trying to grow. I'll try to answer this "in general" instead of being specific to one size plant. Light seen and perceived with the human eye is measured in Lumens. There is an ideal amount of lumens for growing and a minimum amount of required lumens. The very minimum amount of light required for smaller sized plants grown is around 3000 lumens per square foot. Let me put emphasis on "minimum amount" of light. However, that's not 100% exactly accurate, since although you may have a 10,000 lumen light, the amount of light that reaches the plant varies with the distance between the light and plants, and the reflectivity of the grow area. The ideal amount is somewhere around 7000-10,000 lumens per square foot for average sized plants. As long as the plants do not show burn, as much light can be used as you want to use. (Note, the sun produces about 10,000 lumens per square foot, on a sunny mid summer day). Contracy to "talk" you CAN have too much light.

Determining lumens for your grow area:
First determine the square footage of your area (example in a 4 foot by 4 foot area, there is 16 square feet, 2 by 2 feet is 4 Sq ft. ) If you have a 1000 Watt High Pressure Sodium Light Bulb, that produces approximately 107,000 lumens. Divide this by 16 (your square footage) 107,000 divided by 16 = 6687 lumens per square foot. So just divide the total amount of Lumens, by the total amount of square feet, and that's your lumens per square foot.



Note on HIDs contributed by PurpDaddy, of RIU:
When given the choice of only one light, most marijuana growers will choose an HPS, High Pressure Sodium grow light over MH, Metal Halide, because HPS lights are more efficient (larger harvest).
You can't use a standard high pressure sodium bulb in a metal halide fixture, but you can use a metal halide bulb in a high pressure sodium fixture of the same wattage.
There are special hps bulbs that can be used in a mh fixture and vice-versa. But these conversion bulbs cost about double the price of a standard bulb.
With HID Lights:
A 250 watt fixture will supply enough light to cover a 2.5 foot by 2.5 foot grow area. (6 plants or less)
A 400 watt fixture will supply enough light to cover a 4 foot by 4 foot grow area. (12 plants or less)
A 600 watt fixture will supply enough light to cover a 5 foot by 5 foot grow area. (18 plants or less)
A 1000 watt fixture will supply enough light to cover a 6.5 foot by 6.5 foot grow area. (30 plants or less)

How far away from my plants do the lights go?
The lights in your grow room should be as close as possible to the plants without burning them. There is no such thing as too much light, unless there is overly sufficient heat to dry out and burn the leaves. A good rule with HIDs is to put your hand under the light, if its too hot for your hand, chances are that the plants will be too hot too, so move the light up until your hand feels more comfortable. For seedlings or sprouts, I keep them a little further away from the light, because they are very susceptible to burning and drying out, at these young stages. Placed too far away, and you will get undesired STRETCHING. (defined later)

I can safely place my 42, 65 and 85 watt bulbs one and a half inches near the plant.
I put the 105 and 200 watt bulbs three inches near.

How do I decide which lights to use?
Efficiency is very important when choosing a type of light. The wattage is not the most important thing, different types of light produce different amounts of lumens per watt. For example, a 300 watt incandescent will produce about 5100 lumens. (not that you can grow with incandescent bulbs) While a 300 watt Metal Halide (just an example, they do not come in 300 watts), will produce 27,000 lumens. Obviously far more efficient for growing, while still using the same amount of electricity.
Can you afford to VENT the HEAT out of the grow area and cool the area? (HID)
Are you on a budget? (CFL)

Approximate estimated light production:
Incandescents: 17 lumens/watt
Mercury vapor: 45-50 lumens/watt
Fluorescents: 60-70 lumens/watt
Metal halide: 90 lumens/watt
High pressure sodium: 107 lumens/watt


Incandescent lights: Incandescent bulbs are the most popular type of lights in the world. They may come advertised as incandescent, tungsten, quartz, halogen, or simply standard. The important thing about incandescent bulbs when it come to growing is simply this: they suck. Using incandescent bulbs to grow plants is like trying to flag down the Space Challenger with a burnt out match! You can do it, but it won't work. There are some incandescents which are sold as "grow lights." They usually have a blue coating and usually come in 60W and 120W sizes. While they may seem like a good choice to new growers, they are next to useless; they produce some light at a usable spectrum, but only have about a 5% efficiency and generate more heat than usable light. Most of us have these in our homes right now. Don't use them for growing, instead opt for a Compact Fluorescent, CFL, as a cheaper but more efficient alternative.

Fluorescent lights: Fluorescents are far more useful than incandescents. They are efficient enough, and much less expensive than HID (High Intensity Discharge) lights. Compact fluorescent tubes, (commonly called CFLs) are popular with growers because of their good output to size ratio. Compared to standard 4 foot tubes, CFLs are smaller, more easily moved, and more can fit into a given small area. CFLs are good for small grows on a tight budget, and for novice growers, since they do not require any special sort of wiring or understanding of the necessary bulbs for a given fixture, and the small wattage ones (23, 42 and 65) are very widely available. Fluorescent lights come in many different Kelvin (spectrum or color) ratings; often the spectrums are labeled on packaging as being 'cool white' or 'warm white.' Cool white is more blue, and is good for the vegetative stages of growth. The bulbs are ultra white. Warm white light is more reddish in spectrum, and is best for the flowering stage. The bulbs are almost cream colored.

Color rating - Measured in Kelvin (K). The higher the number, the more bluish the light. 4000K-7000K is mostly on the blue side of the spectrum for Vegging or GROWING, while 3000K and under goes from a white spectrum, to a redder spectrum and is best for BLOOMING or FLOWERING.
There is NOT one CFL bulb for both spectrums, two different kelvin bulbs are needed.
This pic shows both COOL WHITE and WARM WHITE, or high and low kelvin bulbs:

One of many mistakes I have made over the years, is I wish I had labeled or dated my bulbs. I highly urge everyone to date-label your bulbs.


Lets look at some Clamp Reflectors:

The above are the CHEAP ones, and not durable.

Below are the very good ones:

IF you see PLASTIC on the Clamp Reflector, they are cheap and flimsey and you should avoid them.

If you plan on using a 105 watt CFL bulb in a Clamp Refector, you will need one of these:

I have come to believe that 2 42 watt bulbs, in one Clamp Reflector is the most efficient, cost effective way to provide light to your Grow.
You also need one of these

and two of these

Available in black or cream colored at Walmart, Lowes, Home Depot and any Hardware store, about $1.69 to $1.99.
They are used to put two 42 watt CFLS in one Reflector.

I also like these:

1 to 4 Sockets Adapter A4E27


This adapter will allow 4 bulbs to be installed in one socket. Each socket on the adapter can support up to 250W, so it support up to 1000W in total.


I have seen these lined up and used in a Surge Protector:

Or try two of these :

in one of these:

One in each side. There is a socket on the bottom of this that u can not see.


One of those equals 3 sockets all 90 degrees apart. ​

Short answer: you can get by with 4 in veg, 6 would be better.

Awesome info.
Thanks.

This about does it.

your space is near perfect for a 250 watt hps. its got 28,500 lumens and is ideal for a 2.5 by 2.5 area. you might need some good ventilation for that area. for the price your gonna spend on all those cfls you could grab a cheap 250 watt hps from www.insidesun.com

So I can get away with two 42w for vegging?



I have come to believe that 2 42 watt bulbs, in one Clamp Reflector is the most efficient, cost effective way to provide light to your Grow.


?

i would go with 4 ,42 watt cfls on top with three in the 6500k and 1 in the 2700k then i would put 1 2700k and 1 6500k on the side of the plant and your one plant should veg good then just switch them during flower so a quick answer is 4 to 6 cfls at the 42 watt range would be goo and your talkin maybe 40 bucks or just go with more and buy the double packs at walmart for 7.44 that are 26 watts and use about 8 of them that 35 bucks and no heat if you have a small fan blowing in the box on the bulbs good luck with your grow and to roseman great info on how the cfls run but thats a week of studing in a 1 question answer but hell look at your rep and mine big diffrence

doworksmegel said:

So I can get away with two 42w for vegging?



I have come to believe that 2 42 watt bulbs, in one Clamp Reflector is the most efficient, cost effective way to provide light to your Grow.


?

Click to expand...

As I posted above, a CFL averages 70 lumens per watt. a 42 watt bulb = 2,940 lumens. 2 42s = 5980 lumens.
As I posted:
There is an ideal amount of lumens for growing and a minimum amount of required lumens. The very minimum amount of light required for smaller sized plants grown is around 3000 lumens per square foot. Let me put emphasis on "minimum amount" of light. However, that's not 100% exactly accurate, since although you may have a 10,000 lumen light, the amount of light that reaches the plant varies with the distance between the light and plants, and the reflectivity of the grow area. The ideal amount is somewhere around 7000-10,000 lumens per square foot for average sized plants. As long as the plants do not show burn, as much light can be used as you want to use. (Note, the sun produces about 10,000 lumens per square foot, on a sunny mid summer day). Contracy to "talk" you CAN have too much light.


so with two 42s, you have the bare minimum for two square feet of plant or grow space. you have 6 sq feet, so NO, you need 6 42s to VEG to have the minimum needed.

go back and read it again. you also need some 2700 K for Flowering, to get the Dual Spectrum..