New to LED: Thoughts, suggestions

[Madtabman]

Hi guys. So I have a Maxibright Daylight 660w pro LED. I've been scrogging under it for 10 days now in veg. And I've got some lovely pre-flowering going on. Im getting a maximum 600umols at canopy at 18/6. My thoughts are to increase umols by 50 then incrementally by 50 or so week to week if thy are happy. Now the light has a distance of 7-9 inches from the canopy at 50% power and they love it honestly I'm so surprised. But the problem I see is if I want to increase the umols for my last bit of strech. I have 2 options lower the light which I don't think is a good idea and raising the light and turning up the power to 75%. Now I just raised the light and upped to 75%. And they are now receiving 675umols maximum. But the light is so far away from the canopy like 50 inches. Which has me wondering a few things. Will the plants strech increase now? Am I overthinking it and maybe I should have just left everything the way it was? Or am I doing it correctly and my job now is to slowly move the light up and down in order of what the plants want and like?

 

[BigBudsBunny]

I'm new with LED's but from what I have read 600@18hrs per day gives you a dli of 38.88. From what I have read they can only take about that much light before additional light becomes unusable. The higher the light is raised, the more uniform the light distribution becomes. My light came with "par" instructions if you will - 100-300 seedlings (18 hrs), 400-600-veg (18 hrs), 800-1000 flower(12 hrs). hope that helps

 

[KingJohnC]

@ladycannafan

 

[Delps8]

I'm new with LED's but from what I have read 600@18hrs per day gives you a dli of 38.88. From what I have read they can only take about that much light before additional light becomes unusable. The higher the light is raised, the more uniform the light distribution becomes. My light came with "par" instructions if you will - 100-300 seedlings (18 hrs), 400-600-veg (18 hrs), 800-1000 flower(12 hrs). hope that helps

Some grows can't handle 500µmol. I've seen that happen twice.

Cannabis will thrive at 1000µmol. I routinely grow at that level but not all grows or strains can handle that. I've run Gorilla Glue, Gelato, Strawberry something, and a few others, autos and photos and they're quite happy at 1k.

Cannabis is a C3 plant which means it doesn't need darkness to do "dark cycle processing". That means you can run it 24/0. I use 24/0 or 20/4 until flip and I grow autos 20/4 all that way through, with DLI as high as in the 80's.

Cannabis sites recommend modest amounts of light for many reasons including an abundance of caution and because of ignorance.

You won't go wrong using 100-300, 400-600, and 800-1k but there's zero reason to use light levels that low. Cannabis yield increases as PPFD increases - it really is that simple. The attached paper shows a 4.5% increase in dry weight yield for every 50µmols of PPFD.

This table is based on the data in the paper.

Check out the You Tube video whose title appears at the bottom of this graphic. The presenter is a PhD student under Dr. Bruce Bugbee and he discusses some of the research he's down for his thesis. It's 50 minutes of no-bullshit straight shooing here's-how-you-do-it info.

Want more weed? Get your plants as much light as they can handle and it's back up the truck time at harvest.

 

[Madtabman]

Some grows can't handle 500µmol. I've seen that happen twice.

Cannabis will thrive at 1000µmol. I routinely grow at that level but not all grows or strains can handle that. I've run Gorilla Glue, Gelato, Strawberry something, and a few others, autos and photos and they're quite happy at 1k.

Cannabis is a C3 plant which means it doesn't need darkness to do "dark cycle processing". That means you can run it 24/0. I use 24/0 or 20/4 until flip and I grow autos 20/4 all that way through, with DLI as high as in the 80's.

Cannabis sites recommend modest amounts of light for many reasons including an abundance of caution and because of ignorance.

You won't go wrong using 100-300, 400-600, and 800-1k but there's zero reason to use light levels that low. Cannabis yield increases as PPFD increases - it really is that simple. The attached paper shows a 4.5% increase in dry weight yield for every 50µmols of PPFD.

This table is based on the data in the paper.

Check out the You Tube video whose title appears at the bottom of this graphic. The presenter is a PhD student under Dr. Bruce Bugbee and he discusses some of the research he's down for his thesis. It's 50 minutes of no-bullshit straight shooing here's-how-you-do-it info.

Want more weed? Get your plants as much light as they can handle and it's back up the truck time at harvest.

Hey. So I so I lowered my light last night and was getting 890 umols in the centre of the canopy. After i did a little super cropping only in the centre. I checked them evey hour. And saw no immediate negative changes like twisting or anything. I've just checked them (11 hours later) now although they look good a couple of them at the centre of the canopy have praying leaves. Now I've heard mixed opinions of this maybe it's a sign they are just getting enough now? I haven't got an average canopy reading because I haven't tackled the formula that @Delps8 posted

 

[Skunksta]

I feel in todays market buy a good light branded and your good to go.
After you get you light levels dailed in.
BUT what i will say is the most even distribution light i have worked with YET.
Has to be the KS lights from @ViparSpectra
Every grow the even canopy is really something.
No hot spots or silly high levels in the centre and poor at the edges.
Prob is there KS5000 MIGHT be alittle under power for a 5x5.
But i would take those 500 watt over your 660 watt.
But you have had sound advice and im sure after getting to know the light you have.
Your have no issues what works in my space/tent/passive cooled / fresh air pumped in / aircon etc etc.
Might not in yours im sure your get things sorted.

 

[KingJohnC]

@Lady Cannafan

 

[Lady Cannafan]

@Lady Cannafan

@KingJohnC , he's asking about the current light he's using. Maxibright Daylight 660w pro LED.
I have not reviewed or used that brand, so I cannot advise anything on it.

I have only reviewed the ViparSpectra KS5000 since I became a product reviewer. (Very impressed with it, and I agree with @Skunksta on the KS series.)

 

[Sativa1970]

There is no such thing as too much light for the plant. Too much light for the environment is how you harm the plant, or waste power. When she is praying you have the right light for the environment. From that point you can not increase the light without improving the environment.

Scientists that made those charts and meters have never seen your grow space. Your plant has never read any of the literature. Yet it is still the leading authority on what is right for your space. Read the plant, not meters and charts.

 

[Madtabman]

I get that and hope to be able to do that one day. like you guys. But as I'm farely new I'm sure following some guidance, meters and charts is best at first. And learning to read the plants as i go.

 

[Delps8]

There is no such thing as too much light for the plant. Too much light for the environment is how you harm the plant, or waste power. When she is praying you have the right light for the environment. From that point you can not increase the light without improving the environment.

I wouldn't rely on plants "praying" to tell you that you're at the light saturation point but I do believe that when plants pray, they are at the light saturation point.

The only time I've seen plants pray is in early and mid-veg. I've taken plants right up to their light saturation point (and a bit further from time to time) but, in flower, they don't pray.

Perhaps that's because I'm not religious…. ;-)

Scientists that made those charts and meters have never seen your grow space. Your plant has never read any of the literature. Yet it is still the leading authority on what is right for your space. Read the plant, not meters and charts.

A light meter will tell you how much light your plant is getting. Your plant will tell you how much light it can use.

A meter will help get your light levels "in the ballpark" but, when you increase light levels, the grower has watch the plant to see how it reacts. Fortunately, it's really hard to damage a plant with an LED. You can piss them off a bit but LED's are nothing like how HPS would heat up the plant.

It's the same with increasing nutrient levels when plants go from seedling to veg to flower. We can think that, say, EC 1.6 is "good" for a plant but it's silly to bump your nutes from 1.0 to 1.6 and disregard how your plants react.

 

[Madtabman]

I wouldn't rely on plants "praying" to tell you that you're at the light saturation point but I do believe that when plants pray, they are at the light saturation point.

The only time I've seen plants pray is in early and mid-veg. I've taken plants right up to their light saturation point (and a bit further from time to time) but, in flower, they don't pray.

Perhaps that's because I'm not religious…. ;-)


A light meter will tell you how much light your plant is getting. Your plant will tell you how much light it can use.

A meter will help get your light levels "in the ballpark" but, when you increase light levels, the grower has watch the plant to see how it reacts. Fortunately, it's really hard to damage a plant with an LED. You can piss them off a bit but LED's are nothing like how HPS would heat up the plant.

It's the same with increasing nutrient levels when plants go from seedling to veg to flower. We can think that, say, EC 1.6 is "good" for a plant but it's silly to bump your nutes from 1.0 to 1.6 and disregard how your plants react.

Hi @Delps8, so are you suggesting that the plants shouldn't be praying on the 14th day of flowering? I'm monitoring them closely and I can't see any twisted leaves or any deformity yet. Maybe this is not even considered praying?

 

[Madtabman]

What is this? is it the first signs of light stress? or is it nutrient tindge maybe?

 

[Sativa1970]

are you suggesting that the plants shouldn't be praying on the 14th day of flowering?

Praying in flower isn't bad, it is just less common. Your plant shifts away from veg as you go into flower. If it stops praying in flower, that is not necessarily a sign there is a problem. Some strains naturally pray all the way to harvest. Some stop mid or even early flower. It is also genetics, not just environmental.

Several things can cause brown tip and darker edges. Humidity, watering, high nitrogen or low phosphorous, calcium or magnesium.

 

[KingJohnC]

when cannabis plants pray its is a magnesium deficiency. 1 teaspoon per gallon epsom salts magnesium sulfate

 

[Delps8]

Praying in flower isn't bad, it is just less common. Your plant shifts away from veg as you go into flower. If it stops praying in flower, that is not necessarily a sign there is a problem. Some strains naturally pray all the way to harvest. Some stop mid or even early flower. It is also genetics, not just environmental.

Several things can cause brown tip and darker edges. Humidity, watering, high nitrogen or low phosphorous, calcium or magnesium.

Good to know — I've only grown a handful of strains so I've never noticed that it only happens with certain ones.

Plants praying is an example of phototropism and is caused by hormones moving from the side that's getting light to the side of the leaf that's not getting light. We see this in plants that "follow the sun" over the course of a day.

When high levels of photon strike one side of a leaf, the hormones move to the shaded side. In the case of a moderately high amount of light, the petiole elevates, which we see as praying.

If light levels continue to increase, more hormones move to the shaded side, curling the edges.

 

[Delps8]

Hi @Delps8, so are you suggesting that the plants shouldn't be praying on the 14th day of flowering? I'm monitoring them closely and I can't see any twisted leaves or any deformity yet. Maybe this is not even considered praying?

I believe that the "praying" response indicates that plants are close to their light saturation point. That's a very good thing because that means they're getting as much light as they can process, via photosynthesis, at that time.

The LSP will change as the environment changes. If the quality of the environment (VPD, nutrient availability, windspeed, etc.) change, the LSP will change. It may change a very small amount but it does change.

When I saw these photos as I was scrolling up the thread, what came to mind was an expression that I used about one of my grows, to whit "these plants are so happy, they ought to get a room!"

The plants are, at this moment, getting a lot of light and their characteristics are characteristics of plants that have received a lot of light - a lot of small leaves, a lot of branches, and, from what I can see, limited internodal space.

In short, they look great!

I'm getting a grow started in the next few days and I'd be pleased as punch if my plants filled out like this.

Keep feeding them well (light is food to a plant, nutrients are akin to vitamins and minerals) and, now that you've got a tent full of leaves, resist the urge to cut them off unless they're severely damaged or if they're very old and deep in the canopy and are yellow(ing) or, and this is applicable here, you can't get more air flowing under the canopy. Bud rot can ruin your day.

 

[bluter]

the praying leaf thing is actually due to systolic osmotic turgor pressure. which is a fancy way of saying the water is rushing to the ends of the leaves and evaporating into the atmosphere.

it's light related, but is not caused by it per se.

it mostly only occurs at the beginning of the day cycle as the plant has loaded up in the dark and is releasing water vapour. indoors it can occur at other times simply due to the type of artificial environment. you'll only really see it outdoor in the morning.

 

[Lady Cannafan]

All of these comments on praying leaves is interesting. We had a discussion on my last grow journal on a couple of my plants doing this during early flower, they were praying "straight up". LOL
Couldn't seem to find a flat out reasoning or common condition to cause it. Didn't hurt a thing, no deficiencies noted.

 

[Madtabman]

I believe that the "praying" response indicates that plants are close to their light saturation point. That's a very good thing because that means they're getting as much light as they can process, via photosynthesis, at that time.

The LSP will change as the environment changes. If the quality of the environment (VPD, nutrient availability, windspeed, etc.) change, the LSP will change. It may change a very small amount but it does change.

When I saw these photos as I was scrolling up the thread, what came to mind was an expression that I used about one of my grows, to whit "these plants are so happy, they ought to get a room!"

The plants are, at this moment, getting a lot of light and their characteristics are characteristics of plants that have received a lot of light - a lot of small leaves, a lot of branches, and, from what I can see, limited internodal space.

In short, they look great!

I'm getting a grow started in the next few days and I'd be pleased as punch if my plants filled out like this.

Keep feeding them well (light is food to a plant, nutrients are akin to vitamins and minerals) and, now that you've got a tent full of leaves, resist the urge to cut them off unless they're severely damaged or if they're very old and deep in the canopy and are yellow(ing) or, and this is applicable here, you can't get more air flowing under the canopy. Bud rot can ruin your day.

I also have a 6 inch oscillating desk fan on the floor. Blowing air around. I forgot to mention that