Lumens per sq. ft.

[mistakeith1]

I need to know the recommended lumens per square foot.

I read this somewhere on the site but can't seem to find it now. If someone could help me out on this it would be great!

 

[MagicCannabus]

Lumens is a terrible measurement system for plant growth, but generally it's all we have. Assuming your light has a decent blend of spectrums, I'd say you want at least 5000 lumens per square foot.

 

[zolar]

lumens lux and footcandles all measure the intensity of a light source

the lumen number on a light bulb package refers to its output at a reference point either at the point source or the surface of the bulb

this output decreases with distance some inverse square ratio
to get a real usable light intensity i use an old fashoned light meter for photography in the incident mode [this is the little
white dome thing -- it measures the light actually falling on the point of measurement]

if money is no object they make a new light meter that measures
plant usable light they are called quantum meters they read in a new unit called micro einsteins they start around 200$

there are tables on the web that give conversion for common light sources to micro einsteins

to make it simple for CFLs at 3=6 inches away you get about 2/3 - 3/4 the lumen number on the package

for hid lights assume low for about half the lumen number at 18 inches away [ you still might have heat issues at that distance]

i did the light meter and tape measure stuff a while ago so this is based on real measurements although i am not a tech geek grower

if you add all your bulb outputs together and divide by the square footage of your cabinet floor you have your minbimum lumens per square ft. actual will be higher because the leaves are closer to the source of light [inverse square thing]

 

[mistakeith1]

Thanks guys. This really helped with what I was trying to figure out and I learned something too! lol

The floor of my space is about 3.6 sq ft (give or take a little) with a little over 3 feet of actual usable height.

On my last grow I was using all CFLs. I'm currently looking around for a 150 watt HPS light. The one I'm interested in says it has an output of 15,000 lumens.

Given the info....I think I should plan on adding some higher watt CFLs closer to the plant(s) in addition to the HPS.

Thanks for all the input. Tell me what ya think.

 

[MagicCannabus]

Your cab is almost the same as mine in terms of area. I have maybe 1.3 more feet of overhead. I do also have a veg area that is 1.5sqft at the bottom and the same height as the flowering side(about 4.3 feet).

Here's what it looks like: Using T8 shop lights to the extreme

 

[cannalearna]

How many plants will grow in your room MagicCannabus?

 

[MagicCannabus]

5 in flower, and however many will fit in veg.

 

[mistakeith1]

I like the cleanly designed box you have going. I'm curious to see how the flowering ladies will grow with that kind of setup. Should be interesting even more fun

I've almost made up my mind to redesign my setup and build a veg chamber underneath the space I have now. I think I can do this and keep the same amount of space up top.

Having both will be better....It will give me more opportunities for projects

 

[MagicCannabus]

I'm definitely a fan of separate veg chambers. With moms and clones, a person could produce a very steady harvest doing a small slick perpetual grow. That's my plan at least. Maybe I'm being optimistic

Anyway, gonna put some mylar on the ceiling of it, and then next Wednesday or Thursday I *should* have plants..... I may start seeds soon either way to make sure I have something going. I hate relying on other people too much...

 

[mistakeith1]

Well you have my wish of luck!

Get them babies goin I'm ready to see that chamber in action

 

[newbuds3]

I have a rather large closet grow area with 9 sq ft. But since my plants are only 4 days old I'm using 120w(actual) CFL over each until my big 650w 4' t5 12 bulb unit gets here. They look more over a week but they're happy as hell. I'm doing soil indoor autos and going to push em for every ounce I and break the boundaries of the breeders note on indoor yields. 2- s.a.d. And 1-sin trabajo. The new unit is pretty sweet with the switches i can power individual 4 bulb sections or all 12. Putting out 60,000 lumens at almost 73w per sq ft. I would post a pic of the girls this far if I could get them to load. Grrrr

 

[scl420]

hi guyz!!this is my 1st time growing and i would appreciate any of your help.well.. how many lumens/s.f actually we need?? i have 2,300 lumens LED for 1.5 s.ft. at 18'' distance away from the plant.. is that good enough or not?..