how much light?

How much light does a pot plant need or want, to grow the healthiest plant?

Do some more reading my friend. To save you this one, MJ needs a minimum of 3,000 lumens per square foot to grow. They are happy with 4-6k per square foot, more doesn't hurt but higher than 6k you're prob gonna be wasting power in heat and light that isn't going to be a positive return for your grow.

Harry Potter said:

How much light does a pot plant need or want, to grow the healthiest plant?

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3000 lumens per square foot minimum, 5000 lumens per square foot recomended.
Here's a sample chart to help you:
23w CFL = 1600 lumens = 69.6 lumens/watt
30w CFL = 2000 lumens = 66.7 lumens/watt
40w CFL = 2600 lumens = 66.3 lumens/watt
150w HPS = 14000 lumens = 93.3 lumens/watt
250w HPS = 28000 lumens = 112 lumens/watt
400w HPS = 50000 lumens = 125 lumens/watt
600w HPS = 90000 lumens = 150 lumens/watt

It looks to me like your saying about 3 30w cfl's will be the right amount for a plant taking up an area of about 2 sq feet in plan view. Do you have to add some for the sides of the plant. Do you take the area of all the green surface. like the average circumference times the height of plant plus area of plan view.

Harry Potter said:

It looks to me like your saying about 3 30w cfl's will be the right amount for a plant taking up an area of about 2 sq feet in plan view. Do you have to add some for the sides of the plant. Do you take the area of all the green surface. like the average circumference times the height of plant plus area of plan view.

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Sounds about right - but keep in mind, the 3000 lumens per sq ft is the minimum amount you want. More is better.

I'd shoot for 4-5k. Thats the range i've seen for a happiness increase. 3k going to 4,750 there is a clear difference. 5k-6.5k? Meh, not as noticeable. A thing to remember is HIDs penetrate the canopy of plants well, CFLs do not do as good of a job. Supplemental lighting below the canopy ain't a bad idea but keep it supplemental. You don't want to confuse the plant and make it think the sun is behind its ass. Keep the bulk of the light above

A few additions: lumens per sq ft means just that. It is not how many lumens are emitted, it is how many reach the target area. So for starters you have to divide the total lumens by the number of sq ft. Then, you have to do an honest estimate of how much light is realling falling on the grow area. Is any at all hitting floors and walls? Of course it is, and 3000 per sq ft minimum doesn't include what is lost. So you really ought to shoot for 5000 lumens generated for every sq ft of grow area, and regard that as a minimum. You can get by with less in early veg, and you really should have more in flower. Both in the correct spectrum ratio as well.

yes lumens are what counts...lets say i have a pc grow case (which I do) its about 1 1/2 foot wide and about 1 1/2 foot tall...i have 3 60 watt 1600 lumen cfls - so 3 x 1600 = 4800 = perfect healthy grow...i recommend lowes or walmart for the cfls...however lowes doesnt offer many cfl with high lumens (or atleast mine didnt) the highest i found was 1600 but i tripled em up and it works fine good luck bro

if you want a good grow you want atleast 6,000 lumes per sq foot

get rid of the cfls get something better you need bigger lights dude

4800 Lumens in my pc case is working great I guess it just depends if you are doing more than a 1 plant you def need something dif tho.