Need Advices : Growing with LED Lights

[hashcraze956]

 

I've started this thread to discuss the best ways to utilize a LED panel to achieve the best results possible. I hope the experienced LED growers will post their best practices to achieve the best results here in one place making it easier for others to improve their grows.

One of the things that prompted me to start this post was distance of the panel from the top of the plants. It is said that in higher wattage panels it is best to keep the lights further away say 28"to 30" to increase the size and density of the buds. I kept my 90 watt Initial-LED Grow Lights at 20" and ended up with smaller fluffier buds and now after learning about the distance making a difference I will try the next grow at 30" to see how much better my buds will be.

You are welcome to give some more advices/suggestions based on your personal experience.

[Naycha]

Common sense says that the further away the light source, the less lumens the plant will receive. My bet is your buds will be even fluffier.

 

Have you considered the led panels are just not up to scratch?

 

Naycha

[tangwena]

90 watts is not a high power unit I had a 120w and I needed to keep it about 150mm from the top of the plant, even then after trying very hard HPS and MH shits all over it. I used the led for a year but will only use it as suplimental lighting now. The guys on this forum have been at it for years and if leds were up to it they would use them.

[merl1n]

Hey there Hash,

As I have said before, I don't use LED's. IMHO being a new technology there is still some fine tuning needed for them to match HID. But I do have some knowledge in regard to electronics and the use of LED's

As Nay stated 'Common sense says that the further away the light source, the less lumens the plant will receive'. You can easily prove this for yourself. I have an LED torch and a incandescent torch. If I shine the incandescent torch at my back fence I get a bright reflection, but with LED the intensity breaks down quickly and the reflection is more  a minimal glow. Now to me this is simple physics. The further away from a light source, the less the intensity.

BUT upon investigating I have also found this  http://www.bonsaihunk.us/info/LEDvsFluoresc.html

 

Inserted below are comments by my LED supplier as to possible complicating factors explaining why the LED's performed poorly under my test conditions.

1. The LED bar should not be mounted closer than 18" from the top of your plants.  For seedlings 20 to 24" should be about right.  By placing your bar closer than the recommended mounting distance plants received too much light (photo-inhibition),  and the light does not have a chance to mix properly before reaching your canopy.  This would cause growth to slow and the plant leaves to grow in an unnatural shape. 

 

Both of these theories conflict but as you can see from Bonsaihunk's experiments, the LED's don't match in results.

 

Merl1n

[nici]

If you intend to use LEDs 90w isnt going to cut it!  You're going to need something 250w or above with 3w diodes however with the stronger diodes you can have bleaching by having the light too close so it's recommened to have the light at the top of your grow space and let the plants grow towards it for a couple of weeks, then slowly bring the light closer (around 12-15" max).  Also you should note that LED plants will need to be flowered a little longer then with HPS/MH.

 

LEDs are a matter of personal needs - You wont grow trees but you will get bud if done right with a decent panel.

[Rosey]

I've been using this panel, The ' TOPLED 450 watt switchable grow lamp ' from 

LEDGROWLIGHTMANUFACTURER-AU

 

 http://www.ebay.com.au/itm/Reflector-450W-Led-Grow-Light-Growth-Flower-Switches-Plant-LED-Grow-Lamp-Panel-/280980989971?pt=AU_Seed_Starting_Hydroponics&hash=item416bc5a813

 

for 4 months. Coming from a background of using 400 or 600 wat HPS and never having any issues whatsoever, always managing a decent harvest without too much fuss, I considered myself a good grower and thought I could make this thing work. Well F@#k me I haven't been able to get anything to grow under the thing. First crop was healthy seedlings on about their 4th set of leaves straight out of my Fluoro powered clone / mother room. I put these healthy and strong plants under the light and they continued to grow for about as week then growth slowed and they started developing what I now know is classic calcium and magnesium deficiencies.

 

Well I scratched my head, checked pH and ec of medium, runoff, everything seemed fine. I did hours off research and did come up with a couple of people suggesting cal mag supplements. So I went to the hydro shop and asked for some cal mag sup and the guy asked me what nutrient was I using etc. I told him I was experimenting with LED and he laughed at me and told me to stop wasting my time and go back to HPS. "no one ever needs cal mag supplements if they are using good nutrient and the right pH and EC" he tells me. He also told me its most likely the feed water is too cold. Any way I got the cal mag anyway, fed some to the plants a couple of times but they got progressively worse over time. It got to the point the leaves were browning off so I cracked it and pulled them out in their containers and put them outside, in the sunshine. Well withing a matter of days they started recovering and growing strong again and flowered out nicely in the winter sunshine (and rain).

 

I have tried two more crops with healthy clones since with exactly the same results. I have precharged my medium (50/25/25 professional potting soil, perlite and coco) with cal mag, ensured the pH is perfect at 6.8 in the medium and I generally have never needed to feed until the start of flowering with the exact same mix in HPS or outdoor situations in the past. The temps are 20 - 22c in the dark and 28 - 30c in the day. The tent has plenty of fresh air in and around 50% RH. I was also very careful not to overwater as these useless lights put out next to no radiant heat.  

 

Plants don't like it! I get decent (altho relatively slow) growth for a week or two then these nutrient deficiencies start to creep in and there doesn't seem to be any turning back no matter what I try. Epsom salts, GH cal mag sup, concentrated dolomite lime.

 

I have given up and will go back to HPS next indoor season. I wouldn't recommend wasting time with LEDS and don't believe the hype you may read on other forums, or at least take it with a pinch of 'epsom salt' .      

[Tracybee]

I've been using this panel, The ' TOPLED 450 watt switchable grow lamp ' from 

LEDGROWLIGHTMANUFACTURER-AU

 

 http://www.ebay.com.au/itm/Reflector-450W-Led-Grow-Light-Growth-Flower-Switches-Plant-LED-Grow-Lamp-Panel-/280980989971?pt=AU_Seed_Starting_Hydroponics&hash=item416bc5a813

 

for 4 months. Coming from a background of using 400 or 600 wat HPS and never having any issues whatsoever, always managing a decent harvest without too much fuss, I considered myself a good grower and thought I could make this thing work. Well F@#k me I haven't been able to get anything to grow under the thing. First crop was healthy seedlings on about their 4th set of leaves straight out of my Fluoro powered clone / mother room. I put these healthy and strong plants under the light and they continued to grow for about as week then growth slowed and they started developing what I now know is classic calcium and magnesium deficiencies.

 

Well I scratched my head, checked pH and ec of medium, runoff, everything seemed fine. I did hours off research and did come up with a couple of people suggesting cal mag supplements. So I went to the hydro shop and asked for some cal mag sup and the guy asked me what nutrient was I using etc. I told him I was experimenting with LED and he laughed at me and told me to stop wasting my time and go back to HPS. "no one ever needs cal mag supplements if they are using good nutrient and the right pH and EC" he tells me. He also told me its most likely the feed water is too cold. Any way I got the cal mag anyway, fed some to the plants a couple of times but they got progressively worse over time. It got to the point the leaves were browning off so I cracked it and pulled them out in their containers and put them outside, in the sunshine. Well withing a matter of days they started recovering and growing strong again and flowered out nicely in the winter sunshine (and rain).

 

I have tried two more crops with healthy clones since with exactly the same results. I have precharged my medium (50/25/25 professional potting soil, perlite and coco) with cal mag, ensured the pH is perfect at 6.8 in the medium and I generally have never needed to feed until the start of flowering with the exact same mix in HPS or outdoor situations in the past. The temps are 20 - 22c in the dark and 28 - 30c in the day. The tent has plenty of fresh air in and around 50% RH. I was also very careful not to overwater as these useless lights put out next to no radiant heat.  

 

Plants don't like it! I get decent (altho relatively slow) growth for a week or two then these nutrient deficiencies start to creep in and there doesn't seem to be any turning back no matter what I try. Epsom salts, GH cal mag sup, concentrated dolomite lime.

 

I have given up and will go back to HPS next indoor season. I wouldn't recommend wasting time with LEDS and don't believe the hype you may read on other forums, or at least take it with a pinch of 'epsom salt' .      

Thanks,Rosey for your words of wisdom. Not just wisdom but experience as well.

I have tried a BlackStar LED array and found similar outcomes to yours.

Let us hope others read your input and think twice about LED's..Even tho they look so gorgeous !!!

[Frank Reynolds]

Interesting mate, what were your temp and humidity at? I ask because I recently had calcium issues in my greenhouse and came to the conclusion that is was too humid. As calcium is taken up through the xylem of a plant, if it ain't taking up water it ain't getting calcium as well.

 

I don't support leds, just saying the switch over could have affected your growing enviorment causing the deficiency rather than the light itself causing it.

 

just my theory at least

[Train Wreck]

Interesting mate, what were your temp and humidity at? I ask because I recently had calcium issues in my greenhouse and came to the conclusion that is was too humid. As calcium is taken up through the xylem of a plant, if it ain't taking up water it ain't getting calcium as well.

 

I don't support leds, just saying the switch over could have affected your growing enviorment causing the deficiency rather than the light itself causing it.

 

just my theory at least

 

You may be onto something there. Either that or some other issue.

There are a lot of crap panels getting around, could also be that. I use a panel like like this http://www.ebay.com.au/itm/321118799317?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649

i did not buy it there or pay that amount though.

I use it to veg my plants, 2 x 400w HPS to flower, have not used it for flower, as I would need 2.      .........

[Ferrethead]

I was looking into LEDs once, but then realised the panels I was looking at getting we're only slightly lower wattage than my HPS. Couple that with the fact they DO generate heat without something like a purpose built hood to vent with......I just can't see the advantage. Not yet.