The Basics Of Plant Lighting

[Ranger275]

Great info. Thank you so.

 

[Mars Hydro]

From our experience.

UV is really very easy to burn out, IR is much better. ver less problem.

WOW, can't believe I didn't find this thread earlier. I almost went crazy looking around the internet for the information that is presented in here.

Thank you very much Hosebomber!

Just a couple of questions... You said to use 35W in bloom for leds. I presume that is actual power consumed, or is it the power of the diodes? I am just a bit too confused with all these different wattages when it comes to leds.

And seconldy, I read that IR and UV diodes made today are not very reliable and break quite often. Do you think it is better to buy a panel that has IR, UV diodes in them, or is better a panel that uses those places for more advantageous diodes and use IR, UV lamps seperately?

Thanks

 

[Hosebomber]

...Just a couple of questions... You said to use 35W in bloom for leds. I presume that is actual power consumed, or is it the power of the diodes? I am just a bit too confused with all these different wattages when it comes to leds.

And seconldy, I read that IR and UV diodes made today are not very reliable and break quite often. Do you think it is better to buy a panel that has IR, UV diodes in them, or is better a panel that uses those places for more advantageous diodes and use IR, UV lamps seperately?

Thanks

My recommendation of 35 watts of LED lighting per square foot in flower is of quality diodes (Cree Phillips, Osram, Nichia, etc.). In the case of most panels, I would recommend 45-50 watts. This is based off of the efficiency of the diode. The above listed diodes (and a few others) produce more photons for the same amount of power draw, in which case you would need less input power to get the same amount light.
Well that's a double edged question. The diodes put in panels for growing are not actually UV and IR but near those wavelengths. The proper term for the 720-740nm diodes is far red. The UV chips are generally 420nm of near UV. There are some companies that claim to use a 380, but I haven't seen one that actually does, and most of the affordable measurement equipment doesn't record that low, so it is hard to quantify their claims. The larger issue with the UV or near UV didoes (at least the ones that are cheap enough to be placed in a panel) is the fact that the resin dome degrades very fast (as fast as 10 hours in some cases).

 

[SuperFunker]

Hello Enki...

UV: I have found UV to be unnecessary and note, UV is dangerous!

IR: When you talk of IR, do really mean 730 to 740nm? If yes, then this range of light is referred to as far red. Far red has been used to induce the Emerson Effect which improves flowering.

TTFN

 

[SuperFunker]

Note: My UV comment is a reference to UV A and B; ie, less than 400nm.

Hello Enki...

UV: I have found UV to be unnecessary and note, UV is dangerous!

IR: When you talk of IR, do really mean 730 to 740nm? If yes, then this range of light is referred to as far red. Far red has been used to induce the Emerson Effect which improves flowering.

TTFN

 

[too old]

As per my handle, it is sometimes hard for me to get a grip on new concepts. (See how I just made all the excuses I need for my questions?) Anyway, you guys seem to have a good grasp on this lighting topic so here goes:

Elsewhere on this site, there are multiple discussions regarding mimicking the sun in regards to diminishing hours of light exposure to our plants. There are also discussions regarding light colour (blue vs. red vs. mixture). From what I gather, the consensus is (for flowering) that any colour will work; red is good; a mix is better. And then add to that the diminishing hours aspect, and Bob's your uncle, it's as good as it gets.

Now, the way I see it (remember I already excused myself for this), at the beginning of the flower cycle, you should hit the plants with full spectrum (the mix) at 100% of the ballast output, for 11 hours. Then say at the three week mark (still using the mixed spectrum), reduce the ballast output to 75% for 10.5 hours, and for the last two or three weeks of flowering, reduce the ballast output to 50% and go straight red for 9.5 hours. Now having said all that, I would be a little leery of cutting the wattage for the last bit by half, so for not being willing to possibly sacrifice bud developement, let's leave the ballast at 75% for the last weeks.

Would this not better mimic the actual seasonal change regarding colour, day length, and light intensity? Or am I just blowing smoke?

Thanks for listening to an old fart.

 

[Hosebomber]

This is a pretty complex question. Yes the change in spectra is due to the angle of the sun. We all get that and understand it. The same for the number of hours of sunlight. The intensity however is where the complexity is. Baring any solar flares and the gradual degradation of the sun the actual intensity of the sun is rather constant. The long wavelengths of Fall and shorter wavelengths of spring give us a difference of intensity based on our measurement of light and PPFD we calculate that there is more intensity. However, the longer wavelengths are used more efficiently and therefore most of the growth of plants (the stretch) is when fall is initiated.

With all of that being said, do not reduce your intensity (wattage) during and at the end of flower. You will see a dramatic reduction in your overall yield. I personally have mixed feeling on the reduction in the number of hours of light. In the few test that I have done, the buds seem to finish a bit faster when reducing from 12/12 to 9/15 hour of day/night cycle but there was a small reduction in overall weight. There are a number of factors that contribute, so I can't say 100% that it was the lighting hours. I currently do a .5 hour every 2 to 3 weeks (depending on strain) so the last week of flower is 10/14.

 

[too old]

Ah yes, HB, of course. This is what happens when they leave me alone and I start thinking. I thank you for setting me back on the straight and narrow.

So, what are your thoughts on the idea of total darkness for the last week or two? As well, would it be done after the complete ripening cycle, or as a replacement for the last week of light? I've read arguments for both sides. My own personal take would be that this is not natural and we would be forcing the plant do something it's not programmed for. However, if someone else has actually seen positive results, it might be worth a try.

 

[SuperFunker]

My recommendation of 35 watts of LED lighting per square foot in flower is of quality diodes (Cree Phillips, Osram, Nichia, etc.). In the case of most panels, I would recommend 45-50 watts. This is based off of the efficiency of the diode. The above listed diodes (and a few others) produce more photons for the same amount of power draw, in which case you would need less input power to get the same amount light.
Well that's a double edged question. The diodes put in panels for growing are not actually UV and IR but near those wavelengths. The proper term for the 720-740nm diodes is far red. The UV chips are generally 420nm of near UV. There are some companies that claim to use a 380, but I haven't seen one that actually does, and most of the affordable measurement equipment doesn't record that low, so it is hard to quantify their claims. The larger issue with the UV or near UV didoes (at least the ones that are cheap enough to be placed in a panel) is the fact that the resin dome degrades very fast (as fast as 10 hours in some cases).

re 35W per 1 sq foot: do you mean 35W of power consumption/output?

 

[Hosebomber]

Yes, 35 watts of power consumption or draw from the wall. Again, that is for quality diodes only. If your panel uses Epi, Epistar, Exotica, Seoul, or SemiLED that number would be closer to 45 or 50 watts per square foot.

 

[SuperFunker]

ty HB... my current project uses Osram

 

[HalfBaked98]

Ive got a question, it's my first try at growing, i put my germinated seed in soil. Ive got an LED lightbulb that is 15W 790 lumens, is this enough to get a seedling growing a little? Any help is much appreciated

 

[Hosebomber]

Yes, it is. It may even be a little intense depending on lenses and how close you have it. I use a mix of 9 one watt blue and white diodes defused for my clones covering a 16" x 22" DIY aerocloner.

 

[HalfBaked98]

This is the bulb, if I put this a little over 12in over the pot (the seed hasn't sprouted leaves or stem yet) would that be beneficial for it's sprouting?

 

[Hosebomber]

Yes, it will be fine. You will want to start increasing the light once you start seeing the 3rd or forth set of leaves.

 

[HalfBaked98]

will it be better than putting it in the sun? The led has a dimmer setting, should i start it not on full light (maybe at 50%) and then when the 3rd set of leaves come up ramp it to 100%?

 

[Hosebomber]

Yes, it will be fine. start increasing the light at the onset of the 3rd or 4th leaf set and make sure to keep the bulb off the plant. Put the back of your hand right over top of you seedling, if you feel heat intensity from the bulb your plant will too.

 

[HalfBaked98]

thanks for the reply. I tried reading the basics of lighting but there are things that I don't really understand. Such as, what are lumens, what do seedlings need to sprout, what conditions? is it fine to leave a pot in the sun? if so, when do i water because after some hours the soil looks quite dry, i dont want to overwater it, but i dont want to underwater it too. Im sure these are all noobie questions. could you tell me a little about your first time?

 

[Hosebomber]

Try reading over this!

 

[jst1376]

hi, i am new to this and i searched on many forums but i did not find an answer that respond to my question. i already had a 250 watt hps and electronic ballast (so it can run a MH bulb aswell) and i have a 175 watt MH bulb sitting. can i use the same ballast for the MH bulb, i wonder if it's going to blow up since the power coming from the ballast is 75 watt more than the bulb itself.

if not, i will get a 250watt mh bulb.

thank you for your help.
cheers