420 Magazine Background

What distance should my light be from my plants?

qlimax1991

New Member
Hi guys,
I'm new on this forum.
I've strated growing indoor, i currently have 4 plants(one looking very bad like it happend something with the seed, but have leafs) and i have a question about it, they are 2 weeks old and i think they are a little overstreched, the lights were allways close to the plants beacuse i'm using cfls, i'll post a pictures so you can see. Another question, in the future i'm planing on building a bigger growbox with MH or HPS lights, curently using a modded pc case. Is it ok to make walls tagged with white plane paper, i'm tight on budget, would definitely use mylar or foylon. pics of my plants:
[/url][/IMG]
[/url][/IMG]
thanks in advance for replying.
qlimax1991
 

The303Stoner

New Member
seeds stretch when they pop. get new blue cool bulbs 6" away is good with a small fan
 

qlimax1991

New Member
seeds stretch when they pop. get new blue cool bulbs 6" away is good with a small fan
Hi,
Today i've made bigger growbox,i'll transplant them in bigger pots and put them under 2 osram neons(1200 lumens) and 2 cfls. i'm currently using 2 120 mm(4,7 inch) fans one in and one out.
hehe im total n00b what does (pop.) means? :D
thanks.
qlimax 1991
 

giggleweed

New Member
what would be a decent height for LED lights to be above the plant in flowering?
I have 2 x 240W flower LED's and am struggling with the optimal height to be using them at.
there won't be much worry on your side if you are growing marijuana plants under LED highteck.. LEd grow lights emit very little heat while providing just the right spectrum needed by the plant. you can put it/set-up LED as close as possible to the top of the plants. don't worry, the tops won't get burn
 

RolliinStoned

New Member
there won't be much worry on your side if you are growing marijuana plants under LED highteck.. LEd grow lights emit very little heat while providing just the right spectrum needed by the plant. you can put it/set-up LED as close as possible to the top of the plants. don't worry, the tops won't get burn
Sorry but I'm going to have to disagree. I will agree that they produce a very small amount of heat when compared to HID's but there is still such a thing as being too close to the tops with LED's. LED's these days can be very powerful and have strong penetration, some LED manufacturers suggest having the lights 12-18" above canopy. If you go closer you may risk light bleaching, this is not always the case but there are reports of light bleaching from LED's if you do a quick search. I guess technically the buds aren't "burning" from excess heat but I still consider light bleaching to be a kind of burn caused by an excessive amount of light. Just my .02
 

jadeashley

New Member
Hey,
I am growing for one of the first times in the house. I have my plants on 24/7 light time. But I've heard that if my leafs seem wrinkled I am giving too muchwater. But I'm as wondeirng about the lights. I am going to add a picture of our set up. I think we need SOME GOOD ADVICE. PLEASE SOMEONE
 

profesor x

Well-Known Member
hello there jadeashley!

you need to get some CFL's (white spectrum 6000k-6500k), those incandescent bulbs you have are not suited for growing!, and that is not the correct light spectrum for your plants in Vegetative stage (they need white light at this stage)

you could add 100w per sq.feet of light and you will be fine.
remember that you will have to change the CFL's with withe spectrum for CFL's of "warm light" for flowering stage.

you can put your CFL bulbs at a distance of 8" from your plant's canopy. they are looking too stretchy and leggy.

hope that some more experienced growers share their knowledge too :3:
cheers
 

jadeashley

New Member
OK for right now, I have to use these lights, but would it be better if they were white, like frosted, UNTILL we can the CFL's But is the distance between to much or too little for right now? Cause that light would be better then NO light wouldn't it?? (like for right now). You say they look stretchy and thats cause there reaching for the light right?? And when should I change there light times?? Like to 6off 18on?? Sorry but I do have a lot of questions. Oh yes, looking at the pictures, Woud you think therestill saveable?? Like there not done for are they???
 

jadeashley

New Member
SOrry but someone told me if my laves look wrinkled they have too much water. Is this true??? And I ave been watering them less since I heard this, but I also find my soil feels really dry on top.
 

Pulsegrow

New Member
Hey bizz, I have a 4 foot 8 (54w) bulb fixture from hydrofarm. I have it about 6" Above plants. Is that to close? Appreciate any feedback, thanks
 

profesor x

Well-Known Member
OK for right now, I have to use these lights
as i said, those lights are not for growing and they make more harm than good to ur plants. there is no correct distance for incandescent lights. if you can't get CFL bulbs, take your plants to a window so they can get solar light instead.

usual light schedules:
veg period= 18 hours of light/6 hours of darkness
flowering period= 12 hours of light/ 12 hours of darkness

lately i have been using GLR (Gas Lantern Routine) that requires less hours, and stress less the plants (as you can see, there is nowhere in the planet where marijuana grows with 18 hours of continuous daylight) and also helps you to reduce your electric bill, with better results.

they still have a chance if you correct your errors.
 

profesor x

Well-Known Member
SOrry but someone told me if my laves look wrinkled they have too much water. Is this true??? And I ave been watering them less since I heard this, but I also find my soil feels really dry on top.
just stick your finger into the ground, if it feels dry down there, you should water, if it is moist, you shouldn't.
 

profesor x

Well-Known Member
Hey bizz, I have a 4 foot 8 (54w) bulb fixture from hydrofarm. I have it about 6" Above plants. Is that to close? Appreciate any feedback, thanks
pulsegrow, are those T5 fluorescent bulbs? if so, what has worked for me is to put seedlings at 1ft distance, because t5 generate more heat than T8 or T12 fluorescent lamps.

if you can't notice burns or something wrong on your plants i guess it is ok with 6"

hope it helps
 

Lbrand66

New Member
For (artificial) light, there is a law that always applies known as the Inverse Square Law. It states that light diminishes exponentially in energy as the distance is increased from the source.

A good example is that you might be getting 1000 PAR Watts at 4" from your light source, but that would change to 250 PAR Watts at double the distance (8"). This law makes it EXTREMELY important for indoor plant growers to get their light source as close as possible to their plants. The amount of light your plant receives is directly related to it's yield/flower density.

The problem: Indoor lamps used for plant cultivation (HID - High Intensity Discharge) give off large amounts of heat, to such a degree that they could cause damage to the plant if put too close.

Indoors, there is an optimum distance/height between the plants and the light source. This distance fully illuminates the whole canopy with direct light from the source, but is as close as possible to the plants for maximum lumen intensity. This will be called the OLH, for Optimum Lamp Height.

Ultimately, to get the best light efficiency from your lamp, you want it at the OLH at all costs. But how can you get it there without causing harm to your plants with the abundant heat?

First, try moving your light to the OLH and see what it does to your plants. If they have no problem, then you're fine. If you have a high output HID, this probably won't be enough.

Next, try actively exhausting your light hood by hooking up a direct exhaust system to the hood, and then move your lamp to the OLH and see if the plants are O.K. If the plants still seemed affected by the heat, then you must add glass to your actively exhausted lamp hood. Glass will absorb/reflect/filter some of the light energy being emitted by the lamp.

The number would seem relatively low, around 2-3% of PAR wattage, but it will effectively filter out almost all of what little UV-B is emmitted by the lamp. UV-B is believed, and has been shown, to have a positive influence on the potency of Cannabis.

Overall, it would be beneficial for one to add glass if needed to keep their lamp at the OLH, due to the all-powerful Inverse Square Law; moving light farther away will greatly reduce the amount of energy being emitted and is reaching your plants (Light intensity is directly related to yield and flower density).

Almost all glass offered today for insertion in air-cooled lamp hoods is tempered glass, which is regular glass with low amounts of impurities. If one was looking for the most efficient glass for their hood, quartz glass will allow the transmission of UV-B, but is not made specifically for light hoods.

And also remember, that if you have a rectangular garden, it is important to position the longest side of the reflector parallel to the shortest side of your garden. (from FAQ by Head Rush)

Additional note: you should periodically inspect and clean your light hood and bulbs, especially after foliar feeding or underleaf spraying for insects. The dust and dirt that collects will definitely decrease reflectivity. Isopropanol alcohol, glass cleaner or water (and a soft cloth) can all be used to remove streaks, dust and spots.

Contributed by: MedMan

There are a number of factors which play a part in the temperature radiated from your bulb, watts, hood design and air circulation for example.

A simple method of testing for temperature is to use the back of your hand; if its too hot for your hand, its too hot for your plants. Good ventilation is the key to getting your light closer to the garden.

Editor's note:

Recommended typical OLH distances:

Flourescentsroximimty
400w HPS: 1 foot
600w HPS: 1.5 foot
1000w HPS: 2 foot

Author: BobbyDigital
So would a 250w hps light with a cooling tube system 2 feet from plant tip at 27 degrees Celsius be any good for a nice crop?
 

Lbrand66

New Member
If the optimum height for a 400w is 12"/30cm, I'd assume you could run your 250w at 12"30cm, if not a little closer.
The temperature is a little high though, I would try to improve ventilation as much as possible.
. The ventilation is sweet I got the humidity at 50 % with about a 600 cubed metre per hour of air being cycled. Just they getting lanky u think cuz it's too far away but if I raise them to under a foot utvwould.cope? Cheers ;)
 

Antics

420 Member
. The ventilation is sweet I got the humidity at 50 % with about a 600 cubed metre per hour of air being cycled. Just they getting lanky u think cuz it's too far away but if I raise them to under a foot utvwould.cope? Cheers ;)
If you're at 24"/60cm now, I would cut that in half at least. If the light isn't strong/close enough, plants will end up stretching a lot.
 
Top Bottom